diff --git a/source/bson-corpus/bson-corpus.md b/source/bson-corpus/bson-corpus.md index 09764f5b8c..7969b138e2 100644 --- a/source/bson-corpus/bson-corpus.md +++ b/source/bson-corpus/bson-corpus.md @@ -37,7 +37,7 @@ pseudo-specification provides such tests. ## Specification The specification for BSON lives at . The `extjson` format specification is -[here](../extended-json.rst). +[here](../extended-json.md). ## Test Plan diff --git a/source/extended-json.md b/source/extended-json.md index 9553f45f79..63bfb7eb7a 100644 --- a/source/extended-json.md +++ b/source/extended-json.md @@ -1,490 +1,337 @@ -============= -Extended JSON -============= +# Extended JSON -:Status: Accepted -:Minimum Server Version: N/A +- Status: Accepted +- Minimum Server Version: N/A -.. contents:: +______________________________________________________________________ --------- +## Abstract -Abstract -======== +MongoDB Extended JSON is a string format for representing BSON documents. This specification defines the canonical +format for representing each BSON type in the Extended JSON format. Thus, a tool that implements Extended JSON will be +able to parse the output of any tool that emits Canonical Extended JSON. It also defines a Relaxed Extended JSON format +that improves readability at the expense of type information preservation. -MongoDB Extended JSON is a string format for representing BSON documents. This -specification defines the canonical format for representing each BSON type in -the Extended JSON format. Thus, a tool that implements Extended JSON will be -able to parse the output of any tool that emits Canonical Extended JSON. It also -defines a Relaxed Extended JSON format that improves readability at the expense -of type information preservation. +## META -META -==== +The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and +"OPTIONAL" in this document are to be interpreted as described in [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt). -The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", -"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be -interpreted as described in `RFC 2119 `_. +### Naming -Naming ------- +Acceptable naming deviations should fall within the basic style of the language. For example, `CanonicalExtendedJSON` +would be a name in Java, where camel-case method names are used, but in Ruby `canonical_extended_json` would be +acceptable. -Acceptable naming deviations should fall within the basic style of the -language. For example, ``CanonicalExtendedJSON`` would be a name in Java, where -camel-case method names are used, but in Ruby ``canonical_extended_json`` would -be acceptable. +## Terms -Terms -===== +*Type wrapper object* - a JSON value consisting of an object with one or more `$`-prefixed keys that collectively encode +a BSON type and its corresponding value using only JSON value primitives. -*Type wrapper object* - a JSON value consisting of an object with one or more -``$``-prefixed keys that collectively encode a BSON type and its corresponding -value using only JSON value primitives. - -*Extended JSON* - A general term for one of many string formats based on the -JSON standard that describes how to represent BSON documents in JSON using -standard JSON types and/or type wrapper objects. This specification gives a +*Extended JSON* - A general term for one of many string formats based on the JSON standard that describes how to +represent BSON documents in JSON using standard JSON types and/or type wrapper objects. This specification gives a formal definition to variations of such a format. -*Relaxed Extended JSON* - A string format based on the JSON standard that -describes BSON documents. Relaxed Extended JSON emphasizes readability and -interoperability at the expense of type preservation. - -*Canonical Extended JSON* - A string format based on the JSON standard that -describes BSON documents. Canonical Extended JSON emphasizes type preservation -at the expense of readability and interoperability. - -*Legacy Extended JSON* - A string format based on the JSON standard that -describes a BSON document. The Legacy Extended JSON format does not describe -a specific, standardized format, and many tools, drivers, and libraries -implement Extended JSON in conflicting ways. - -Specification -============= - -Extended JSON Format --------------------- - -The Extended JSON grammar extends the JSON grammar as defined in `section 2`_ of -the `JSON specification`_ by augmenting the possible JSON values as defined in -`Section 3`_. This specification defines two formats for Extended JSON: - -* Canonical Extended JSON -* Relaxed Extended JSON - -An Extended JSON value MUST conform to one of these two formats as described -in the table below. - -.. _section 2: https://tools.ietf.org/html/rfc7159#section-2 -.. _section 3: https://tools.ietf.org/html/rfc7159#section-3 - -Notes on grammar -................ - -* Key order: - - * Keys within Canonical Extended JSON type wrapper objects SHOULD be emitted - in the order described. - - * Keys within Relaxed Extended JSON type wrapper objects are unordered. - -* Terms in *italics* represent types defined elsewhere in the table or in the - `JSON specification`_. - -* JSON *numbers* (as defined in `Section 6`_ of the JSON specification) include - both integer and floating point types. For the purpose of this document, we - define the following subtypes: - - * Type *integer* means a JSON *number* without *frac* or *exp* components; - this is expressed in the JSON spec grammar as ``[minus] int``. - - * Type *non-integer* means a JSON *number* that is not an *integer*; it - must include either a *frac* or *exp* component or both. - - * Type *pos-integer* means a non-negative JSON *number* without *frac* - or *exp* components; this is expressed in the JSON spec grammar as ``int``. - -* A *hex string* is a JSON *string* that contains only hexadecimal - digits [0-9a-f]. It SHOULD be emitted lower-case, but MUST be read - in a case-insensitive fashion. - -* detail the contents of a value, including type information. - -* \[Square brackets\] specify a type constraint that restricts the specification - to a particular range or set of values. - -.. _section 6: https://tools.ietf.org/html/rfc7159#section-6 - -Conversion table -................ - -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|**BSON 1.1 Type or |**Canonical Extended JSON Format** |**Relaxed Extended JSON Format** | -|Convention** | | | -+====================+==========================================================+=======================================================+ -|ObjectId |{"$oid": | -| |string*>} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Symbol |{"$symbol": *string*} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|String |*string* | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Int32 |{"$numberInt": <32-bit signed integer as a *string*>} | *integer* | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Int64 |{"$numberLong": <64-bit signed integer as a *string*>} | *integer* | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Double \[finite\] |{"$numberDouble": <64-bit signed floating point as a | *non-integer* | -| |decimal *string*>} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Double |{"$numberDouble": | -|\[non-finite\] |"-Infinity", or "NaN">} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Decimal128 |{"$numberDecimal": } [#]_ | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Binary |{"$binary": {"base64": | -| |``=``) payload as a *string*>, "subType": }} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Code |{"$code": *string*} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|CodeWScope |{"$code": *string*, "$scope": *Document*} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Document |*object* (with Extended JSON extensions) | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Timestamp |{"$timestamp": {"t": *pos-integer*, "i": *pos-integer*}} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Regular Expression |{"$regularExpression": {pattern: *string*, | | -| |"options": }} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|DBPointer |{"$dbPointer": {"$ref": , | | -| |"$id": *ObjectId*}} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Datetime |{"$date": {"$numberLong": <64-bit signed integer | {"$date": }} | as described in RFC-3339 [#]_ with maximum time | -|to 9999 inclusive\] | | precision of milliseconds [#]_ as a *string*>} | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Datetime |{"$date": {"$numberLong": <64-bit signed integer | | -|\[year before 1970 |giving millisecs relative to the epoch, as a *string*>}} | | -|or after 9999\] | | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|DBRef [#]_ |{"$ref": , "$id": | | -| |} | | -|Note: this is not | | | -|technically a BSON |If the generator supports DBRefs with a database | | -|type, but it is a |component, and the database component is nonempty: | | -|common convention. | | | -| |{"$ref": , | | -| | "$id": , | | -| | "$db": } | | -| | | | -| |DBRefs may also have other fields, which MUST appear after| | -| |``$id`` and ``$db`` (if supported). | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|MinKey |{"$minKey": 1} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|MaxKey |{"$maxKey": 1} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Undefined |{"$undefined": *true*} | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Array |*array* | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Boolean |*true* or *false* | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ -|Null |*null* | | -+--------------------+----------------------------------------------------------+-------------------------------------------------------+ - -.. [#] This MUST conform to the `Decimal128 specification`_ - -.. [#] BSON Regular Expression options MUST be in alphabetical order. - -.. [#] See https://www.mongodb.com/docs/manual/reference/glossary/#term-namespace - -.. [#] See https://tools.ietf.org/html/rfc3339#section-5.6 - -.. [#] Fractional seconds SHOULD have exactly 3 decimal places if the fractional part - is non-zero. Otherwise, fractional seconds SHOULD be omitted if zero. - -.. [#] See https://www.mongodb.com/docs/manual/reference/database-references/#dbrefs - -.. _Decimal128 specification: ./bson-decimal128/decimal128.md#writing-to-extended-json - -Representation of Non-finite Numeric Values -........................................... - -Following the `Extended JSON format for the Decimal128 type`_, non-finite numeric -values are encoded as follows: - -+----------------------------------------+----------------------------------------+ -|**Value** |**String** | -+========================================+========================================+ -|Positive Infinity |``Infinity`` | -+----------------------------------------+----------------------------------------+ -|Negative Infinity |``-Infinity`` | -+----------------------------------------+----------------------------------------+ -|NaN (all variants) |``NaN`` | -+----------------------------------------+----------------------------------------+ - -.. _Extended JSON format for the Decimal128 type: ./bson-decimal128/decimal128.md#to-string-representation - -For example, a BSON floating-point number with a value of negative infinity -would be encoded as Extended JSON as follows:: - - {"$numberDouble": "-Infinity"} - -Parsers -------- - -An Extended JSON parser (hereafter just "parser") is a tool that transforms an -Extended JSON string into another representation, such as BSON or a -language-native data structure. - -By default, a parser MUST accept values in either Canonical Extended JSON -format or Relaxed Extended JSON format as described in this specification. A -parser MAY allow users to restrict parsing to only Canonical Extended JSON -format or only Relaxed Extended JSON format. - -A parser MAY also accept strings that adhere to other formats, such as -Legacy Extended JSON formats emitted by old versions of mongoexport or -other tools, but only if explicitly configured to do so. - -A parser that accepts Legacy Extended JSON MUST be configurable such that a JSON -text of a MongoDB query filter containing the `regex`_ query operator can be -parsed, e.g.:: - - { "$regex": { - "$regularExpression" : { "pattern": "foo*", "options": "" } - }, - "$options" : "ix" +*Relaxed Extended JSON* - A string format based on the JSON standard that describes BSON documents. Relaxed Extended +JSON emphasizes readability and interoperability at the expense of type preservation. + +*Canonical Extended JSON* - A string format based on the JSON standard that describes BSON documents. Canonical Extended +JSON emphasizes type preservation at the expense of readability and interoperability. + +*Legacy Extended JSON* - A string format based on the JSON standard that describes a BSON document. The Legacy Extended +JSON format does not describe a specific, standardized format, and many tools, drivers, and libraries implement Extended +JSON in conflicting ways. + +## Specification + +### Extended JSON Format + +The Extended JSON grammar extends the JSON grammar as defined in +[section 2](https://tools.ietf.org/html/rfc7159#section-2) of the +[JSON specification](https://tools.ietf.org/html/rfc7159) by augmenting the possible JSON values as defined in +[Section 3](https://tools.ietf.org/html/rfc7159#section-3). This specification defines two formats for Extended JSON: + +- Canonical Extended JSON +- Relaxed Extended JSON + +An Extended JSON value MUST conform to one of these two formats as described in the table below. + +#### Notes on grammar + +- Key order: + - Keys within Canonical Extended JSON type wrapper objects SHOULD be emitted in the order described. + - Keys within Relaxed Extended JSON type wrapper objects are unordered. +- Terms in *italics* represent types defined elsewhere in the table or in the + [JSON specification](https://tools.ietf.org/html/rfc7159). +- JSON *numbers* (as defined in [Section 6](https://tools.ietf.org/html/rfc7159#section-6) of the JSON specification) + include both integer and floating point types. For the purpose of this document, we define the following subtypes: + - Type *integer* means a JSON *number* without *frac* or *exp* components; this is expressed in the JSON spec grammar + as `[minus] int`. + - Type *non-integer* means a JSON *number* that is not an *integer*; it must include either a *frac* or *exp* + component or both. + - Type *pos-integer* means a non-negative JSON *number* without *frac* or *exp* components; this is expressed in the + JSON spec grammar as `int`. +- A *hex string* is a JSON *string* that contains only hexadecimal digits `[0-9a-f]`. It SHOULD be emitted lower-case, + but MUST be read in a case-insensitive fashion. +- `` detail the contents of a value, including type information. +- `[Square brackets]` specify a type constraint that restricts the specification to a particular range or set of values. + +#### Conversion table + +| **BSON 1.1 Type or Convention** | **Canonical Extended JSON Format** | **Relaxed Extended JSON Format** | +| ------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | +| ObjectId | {"$oid": \} | | +| Symbol | {"$symbol": _string_} | | +| String | _string_ | | +| Int32 | {"$numberInt": \<32-bit signed integer as a _string_>} | _integer_ | +| Int64 | {"$numberLong": \<64-bit signed integer as a _string_>} | _integer_ | +| Double \[finite\] | {"$numberDouble": \<64-bit signed floating point as a decimal _string_>} | _non-integer_ | +| Double \[non-finite\] | {"$numberDouble": \} | | +| Decimal128 | {"$numberDecimal": }[^1] | | +| Binary | {"$binary": {"base64": \, "subType": }} | | +| Code | {"$code": _string_} | | +| CodeWScope | {"$code": _string_, "$scope": _Document_} | | +| Document | _object_ (with Extended JSON extensions) | | +| Timestamp | {"$timestamp": {"t": _pos-integer_, "i": _pos-integer_}} | | +| Regular Expression | {"$regularExpression": {pattern: _string_, "options": \}} | | +| DBPointer | {"$dbPointer": {"$ref": \, "$id": _ObjectId_}} | | +| Datetime \[year from 1970 to 9999 inclusive\] | {"$date": {"$numberLong": \<64-bit signed integer giving millisecs relative to the epoch, as a _string_>}} | {"$date": \} | +| Datetime \[year before 1970 or after 9999\] | {"$date": {"$numberLong": \<64-bit signed integer giving millisecs relative to the epoch, as a _string_>}} | | +| DBRef[^6]

Note: this is not technically a BSON type, but it is a common convention. | {"$ref": , "$id": }

If the generator supports DBRefs with a database component, and the database component is nonempty:

{"$ref": ,

"$id": , "$db": }

DBRefs may also have other fields, which MUST appear after `$id` and `$db` (if supported). | | +| MinKey | {"$minKey": 1} | | +| MaxKey | {"$maxKey": 1} | | +| Undefined | {"$undefined": _true_} | | +| Array | _array_ | | +| Boolean | _true_ or _false_ | | +| Null | _null_ | | + +______________________________________________________________________ + +#### Representation of Non-finite Numeric Values + +Following the [Extended JSON format for the Decimal128 type](./bson-decimal128/decimal128.md#to-string-representation), +non-finite numeric values are encoded as follows: + +| **Value** | **String** | +| ------------------ | ----------- | +| Positive Infinity | `Infinity` | +| Negative Infinity | `-Infinity` | +| NaN (all variants) | `NaN` | + +For example, a BSON floating-point number with a value of negative infinity would be encoded as Extended JSON as +follows: + +``` +{"$numberDouble": "-Infinity"} +``` + +### Parsers + +An Extended JSON parser (hereafter just "parser") is a tool that transforms an Extended JSON string into another +representation, such as BSON or a language-native data structure. + +By default, a parser MUST accept values in either Canonical Extended JSON format or Relaxed Extended JSON format as +described in this specification. A parser MAY allow users to restrict parsing to only Canonical Extended JSON format or +only Relaxed Extended JSON format. + +A parser MAY also accept strings that adhere to other formats, such as Legacy Extended JSON formats emitted by old +versions of mongoexport or other tools, but only if explicitly configured to do so. + +A parser that accepts Legacy Extended JSON MUST be configurable such that a JSON text of a MongoDB query filter +containing the [regex](https://www.mongodb.com/docs/manual/reference/operator/query/regex/) query operator can be +parsed, e.g.: + +```javascript +{ "$regex": { + "$regularExpression" : { "pattern": "foo*", "options": "" } + }, + "$options" : "ix" +} +``` + +or: + +```javascript +{ "$regex": { + "$regularExpression" : { "pattern": "foo*", "options": "" } } +} +``` -or:: - - { "$regex": { - "$regularExpression" : { "pattern": "foo*", "options": "" } - } - } - -A parser that accepts Legacy Extended JSON MUST be configurable such that a JSON -text of a MongoDB query filter containing the `type`_ query operator can be -parsed, e.g.:: - - { "zipCode" : { $type : 2 } } - -or:: - - { "zipCode" : { $type : "string" } } - -A parser SHOULD support at least 200 `levels of nesting`_ in an Extended JSON -document but MAY set other limits on strings it can accept as defined in -`section 9`_ of the `JSON specification`_. - -When parsing a JSON object other than the top-level object, the presence of a -``$``-prefixed key indicates the object could be a type wrapper object as -described in the Extended JSON `Conversion table`_. In such a case, the parser -MUST follow these rules, unless configured to allow Legacy Extended JSON, -in which case it SHOULD follow these rules: - -* Parsers MUST NOT consider key order as having significance. For example, - the document ``{"$code": "function(){}", "$scope": {}}`` must be considered - identical to ``{"$scope": {}, "$code": "function(){}"}``. - -* If the parsed object contains any of the special **keys** for a type in the - `Conversion table`_ (e.g. ``"$binary"``, ``"$timestamp"``) then it must - contain exactly the keys of the type wrapper. Any missing or extra keys - constitute an error. - - DBRef is the lone exception to this rule, as it is only a common convention - and not a proper type. An object that resembles a DBRef but fails to fully - comply with its structure (e.g. has ``$ref`` but missing ``$id``) MUST be left - as-is and MUST NOT constitute an error. - -* If the **keys** of the parsed object exactly match the **keys** of a type - wrapper in the Conversion table, and the **values** of the parsed object have - the correct type for the type wrapper as described in the Conversion table, - then the parser MUST interpret the parsed object as a type wrapper object of - the corresponding type. - -* If the **keys** of the parsed object exactly match the **keys** of a type - wrapper in the Conversion table, but any of the **values** are of an incorrect - type, then the parser MUST report an error. - -* If the ``$``-prefixed key does not match a known type wrapper in the - Conversion table, the parser MUST NOT raise an error and MUST leave the value - as-is. See `Restrictions and limitations`_ for additional information. - -.. _regex: https://www.mongodb.com/docs/manual/reference/operator/query/regex/ - -.. _type: https://www.mongodb.com/docs/manual/reference/operator/query/type/ +A parser that accepts Legacy Extended JSON MUST be configurable such that a JSON text of a MongoDB query filter +containing the [type](https://www.mongodb.com/docs/manual/reference/operator/query/type/) query operator can be parsed, +e.g.: -.. _section 9: https://tools.ietf.org/html/rfc7159#section-9 +```javascript +{ "zipCode" : { $type : 2 } } +``` -.. _JSON specification: https://tools.ietf.org/html/rfc7159 +or: -Special rules for parsing JSON numbers -...................................... +```javascript +{ "zipCode" : { $type : "string" } } +``` -The Relaxed Extended JSON format uses JSON numbers for several different -BSON types. In order to allow parsers to use language-native JSON decoders -(which may not distinguish numeric type when parsing), the following rules apply -to parsing JSON numbers: +A parser SHOULD support at least 200 \[levels of nesting\](#levels of nesting) in an Extended JSON document but MAY set +other limits on strings it can accept as defined in [section 9](https://tools.ietf.org/html/rfc7159#section-9) of the +[JSON specification](https://tools.ietf.org/html/rfc7159). -* If the number is a *non-integer*, parsers SHOULD interpret it as BSON Double. +When parsing a JSON object other than the top-level object, the presence of a `$`-prefixed key indicates the object +could be a type wrapper object as described in the Extended JSON [Conversion table](#conversion-table). In such a case, +the parser MUST follow these rules, unless configured to allow Legacy Extended JSON, in which case it SHOULD follow +these rules: -* If the number is an *integer*, parsers SHOULD interpret it as being of the - smallest BSON integer type that can represent the number exactly. If a parser - is unable to represent the number exactly as an integer (e.g. a large 64-bit - number on a 32-bit platform), it MUST interpret it as a BSON Double even if - this results in a loss of precision. The parser MUST NOT interpret it as a - BSON String containing a decimal representation of the number. +- Parsers MUST NOT consider key order as having significance. For example, the document + `{"$code": "function(){}", "$scope": {}}` must be considered identical to `{"$scope": {}, "$code": "function(){}"}`. -Special rules for parsing ``$uuid`` fields -.......................................... +- If the parsed object contains any of the special **keys** for a type in the [Conversion table](#conversion-table) + (e.g. `"$binary"`, `"$timestamp"`) then it must contain exactly the keys of the type wrapper. Any missing or extra + keys constitute an error. -As per the `UUID specification`_, Binary subtype 3 or 4 are used to -represent UUIDs in BSON. Consequently, UUIDs are handled as per the -convention described for the ``Binary`` type in the `Conversion table`_, -e.g. the following document written with the MongoDB Python Driver:: + DBRef is the lone exception to this rule, as it is only a common convention and not a proper type. An object that + resembles a DBRef but fails to fully comply with its structure (e.g. has `$ref` but missing `$id`) MUST be left as-is + and MUST NOT constitute an error. - {"Binary": uuid.UUID("c8edabc3-f738-4ca3-b68d-ab92a91478a3")} +- If the **keys** of the parsed object exactly match the **keys** of a type wrapper in the Conversion table, and the + **values** of the parsed object have the correct type for the type wrapper as described in the Conversion table, then + the parser MUST interpret the parsed object as a type wrapper object of the corresponding type. -is transformed into the following (newlines and spaces added for readability):: +- If the **keys** of the parsed object exactly match the **keys** of a type wrapper in the Conversion table, but any of + the **values** are of an incorrect type, then the parser MUST report an error. - {"Binary": { - "$binary": { - "base64": "yO2rw/c4TKO2jauSqRR4ow==", - "subType": "04"} - } - } +- If the `$`-prefixed key does not match a known type wrapper in the Conversion table, the parser MUST NOT raise an + error and MUST leave the value as-is. See [Restrictions and limitations](#restrictions-and-limitations) for additional + information. -.. note:: The above described type conversion assumes that - UUID representation is set to ``STANDARD``. See the `UUID specification`_ - for more information about UUID representations. +#### Special rules for parsing JSON numbers -While this transformation preserves BSON subtype information (since -UUIDs can be represented as BSON subtype 3 *or* 4), base64-encoding -is not the standard way of representing UUIDs and using it makes comparing -these values against textual representations coming from platform libraries -difficult. Consequently, we also allow UUIDs to be represented in extended -JSON as:: +The Relaxed Extended JSON format uses JSON numbers for several different BSON types. In order to allow parsers to use +language-native JSON decoders (which may not distinguish numeric type when parsing), the following rules apply to +parsing JSON numbers: - {"$uuid": } +- If the number is a *non-integer*, parsers SHOULD interpret it as BSON Double. +- If the number is an *integer*, parsers SHOULD interpret it as being of the smallest BSON integer type that can + represent the number exactly. If a parser is unable to represent the number exactly as an integer (e.g. a large 64-bit + number on a 32-bit platform), it MUST interpret it as a BSON Double even if this results in a loss of precision. The + parser MUST NOT interpret it as a BSON String containing a decimal representation of the number. -The rules for generating the canonical string representation of a -UUID are defined in -`RFC 4122 Section 3 `_. -Use of this format result in a more readable extended JSON -representation of the UUID from the previous example:: +#### Special rules for parsing `$uuid` fields - {"Binary": { - "$uuid": "c8edabc3-f738-4ca3-b68d-ab92a91478a3" - } - } +As per the [UUID specification](https://github.com/mongodb/specifications/blob/master/source/uuid.rst), Binary subtype 3 +or 4 are used to represent UUIDs in BSON. Consequently, UUIDs are handled as per the convention described for the +`Binary` type in the [Conversion table](#conversion-table), e.g. the following document written with the MongoDB Python +Driver: -Parsers MUST interpret the ``$uuid`` key as BSON Binary subtype 4. -Parsers MUST accept textual representations of UUIDs that omit the -URN prefix (usually ``urn:uuid:``). Parsers MAY also accept textual -representations of UUIDs that omit the hyphens between hex character -groups (e.g. ``c8edabc3f7384ca3b68dab92a91478a3``). +```javascript +{"Binary": uuid.UUID("c8edabc3-f738-4ca3-b68d-ab92a91478a3")} +``` -.. _UUID specification: https://github.com/mongodb/specifications/blob/master/source/uuid.rst +is transformed into the following (newlines and spaces added for readability): -Generators ----------- - -An Extended JSON generator (hereafter just "generator") produces strings in an -Extended JSON format. +```javascript +{"Binary": { + "$binary": { + "base64": "yO2rw/c4TKO2jauSqRR4ow==", + "subType": "04"} + } +} +``` + +> [!NOTE] +> The above described type conversion assumes that UUID representation is set to `STANDARD`. See the +> [UUID specification](https://github.com/mongodb/specifications/blob/master/source/uuid.rst) for more information about +> UUID representations. + +While this transformation preserves BSON subtype information (since UUIDs can be represented as BSON subtype 3 *or* 4), +base64-encoding is not the standard way of representing UUIDs and using it makes comparing these values against textual +representations coming from platform libraries difficult. Consequently, we also allow UUIDs to be represented in +extended JSON as: + +```javascript +{"$uuid": } +``` + +The rules for generating the canonical string representation of a UUID are defined in +[RFC 4122 Section 3](https://tools.ietf.org/html/rfc4122#section-3). Use of this format result in a more readable +extended JSON representation of the UUID from the previous example: + +```javascript +{"Binary": { + "$uuid": "c8edabc3-f738-4ca3-b68d-ab92a91478a3" + } +} +``` -A generator MUST allow users to produce strings in either the Canonical -Extended JSON format or the Relaxed Extended JSON format. If generators -provide a default format, the default SHOULD be the Relaxed Extended JSON -format. +Parsers MUST interpret the `$uuid` key as BSON Binary subtype 4. Parsers MUST accept textual representations of UUIDs +that omit the URN prefix (usually `urn:uuid:`). Parsers MAY also accept textual representations of UUIDs that omit the +hyphens between hex character groups (e.g. `c8edabc3f7384ca3b68dab92a91478a3`). -A generator MAY be capable of exporting strings that adhere to other -formats, such as Legacy Extended JSON formats. +### Generators -A generator SHOULD support at least 100 `levels of nesting`_ in a BSON -document. +An Extended JSON generator (hereafter just "generator") produces strings in an Extended JSON format. -Transforming BSON -................. +A generator MUST allow users to produce strings in either the Canonical Extended JSON format or the Relaxed Extended +JSON format. If generators provide a default format, the default SHOULD be the Relaxed Extended JSON format. -Given a BSON document (e.g. a buffer of bytes meeting the requirements of the -BSON specification), a generator MUST use the corresponding JSON values or -Extended JSON type wrapper objects for the BSON type given in the Extended JSON -`Conversion table`_ for the desired format. When transforming a BSON document -into Extended JSON text, a generator SHOULD emit the JSON keys and values in -the same order as given in the BSON document. +A generator MAY be capable of exporting strings that adhere to other formats, such as Legacy Extended JSON formats. -Transforming Language-Native data -................................. +A generator SHOULD support at least 100 \[levels of nesting\](#levels of nesting) in a BSON document. -Given language-native data (e.g. type primitives, container types, classes, -etc.), if there is a semantically-equivalent BSON type for a given -language-native type, a generator MUST use the corresponding JSON values or -Extended JSON type wrapper objects for the BSON type given in the Extended JSON -`Conversion table`_ for the desired format. For example, a Python ``datetime`` -object must be represented the same as a BSON datetime type. A generator -SHOULD error if a language-native type has no semantically-equivalent BSON -type. +#### Transforming BSON -Format and Method Names -....................... +Given a BSON document (e.g. a buffer of bytes meeting the requirements of the BSON specification), a generator MUST use +the corresponding JSON values or Extended JSON type wrapper objects for the BSON type given in the Extended JSON +[Conversion table](#conversion-table) for the desired format. When transforming a BSON document into Extended JSON text, +a generator SHOULD emit the JSON keys and values in the same order as given in the BSON document. -The following format names SHOULD be used for selecting formats for generator -output: +#### Transforming Language-Native data -* ``canonicalExtendedJSON`` (references Canonical Extended JSON as described in - this specification) +Given language-native data (e.g. type primitives, container types, classes, etc.), if there is a semantically-equivalent +BSON type for a given language-native type, a generator MUST use the corresponding JSON values or Extended JSON type +wrapper objects for the BSON type given in the Extended JSON [Conversion table](#conversion-table) for the desired +format. For example, a Python `datetime` object must be represented the same as a BSON datetime type. A generator SHOULD +error if a language-native type has no semantically-equivalent BSON type. -* ``relaxedExtendedJSON`` (references Relaxed Extended JSON as described in - this specification) +#### Format and Method Names -* ``legacyExtendedJSON`` (if supported: references Legacy Extended JSON, - with implementation-defined behavior) +The following format names SHOULD be used for selecting formats for generator output: -Generators MAY use these format names as part of function/method names or MAY -use them as arguments or constants, as needed. +- `canonicalExtendedJSON` (references Canonical Extended JSON as described in this specification) +- `relaxedExtendedJSON` (references Relaxed Extended JSON as described in this specification) +- `legacyExtendedJSON` (if supported: references Legacy Extended JSON, with implementation-defined behavior) -If a generator provides a generic `to_json` or `to_extended_json` method, it -MUST default to producing Relaxed Extended JSON or MUST be deprecated in -favor of a spec-compliant method. +Generators MAY use these format names as part of function/method names or MAY use them as arguments or constants, as +needed. -Restrictions and limitations ----------------------------- +If a generator provides a generic `to_json` or `to_extended_json` method, it MUST default to producing Relaxed Extended +JSON or MUST be deprecated in favor of a spec-compliant method. -Extended JSON is designed primarily for testing and human inspection of BSON -documents. It is not designed to reliably round-trip BSON documents. One -fundamental limitation is that JSON objects are inherently unordered and -BSON objects are ordered. +### Restrictions and limitations -Further, Extended JSON uses ``$``-prefixed keys in type wrappers and has no -provision for escaping a leading ``$`` used elsewhere in a document. This -means that the Extended JSON representation of a document with ``$``-prefixed -keys could be indistinguishable from another document with a type wrapper with -the same keys. +Extended JSON is designed primarily for testing and human inspection of BSON documents. It is not designed to reliably +round-trip BSON documents. One fundamental limitation is that JSON objects are inherently unordered and BSON objects are +ordered. -Extended JSON formats SHOULD NOT be used in contexts where ``$``-prefixed keys -could exist in BSON documents (with the exception of the DBRef convention, -which is accounted for in this spec). +Further, Extended JSON uses `$`-prefixed keys in type wrappers and has no provision for escaping a leading `$` used +elsewhere in a document. This means that the Extended JSON representation of a document with `$`-prefixed keys could be +indistinguishable from another document with a type wrapper with the same keys. -Test Plan -========= +Extended JSON formats SHOULD NOT be used in contexts where `$`-prefixed keys could exist in BSON documents (with the +exception of the DBRef convention, which is accounted for in this spec). -Drivers, tools, and libraries can test their compliance to this specification by -running the tests in version 2.0 and above of the `BSON Corpus Test Suite`_. +## Test Plan -.. _BSON Corpus Test Suite: https://github.com/mongodb/specifications/blob/master/source/bson-corpus/bson-corpus.rst +Drivers, tools, and libraries can test their compliance to this specification by running the tests in version 2.0 and +above of the [BSON Corpus Test Suite](./bson-corpus/bson-corpus.md). -Examples -======== +## Examples -Canonical Extended JSON Example -------------------------------- +### Canonical Extended JSON Example -Consider the following document, written with the MongoDB Python Driver:: +Consider the following document, written with the MongoDB Python Driver: - { +```javascript +{ "_id": bson.ObjectId("57e193d7a9cc81b4027498b5"), "String": "string", "Int32": 42, @@ -511,446 +358,371 @@ Consider the following document, written with the MongoDB Python Driver:: "Minkey": bson.MinKey(), "Maxkey": bson.MaxKey(), "Null": None - } - -The above document is transformed into the following (newlines and spaces added -for readability):: - - { - "_id": { - "$oid": "57e193d7a9cc81b4027498b5" - }, - "String": "string", - "Int32": { - "$numberInt": "42" - }, - "Int64": { - "$numberLong": "42" - }, - "Double": { - "$numberDouble": "42.42" - }, - "Decimal": { - "$numberDecimal": "1234.5" - }, - "Binary": { - "$binary": { - "base64": "yO2rw/c4TKO2jauSqRR4ow==", - "subType": "04" - } - }, - "BinaryUserDefined": { - "$binary": { - "base64": "MTIz", - "subType": "80" - } - }, - "Code": { - "$code": "function() {}" - }, - "CodeWithScope": { - "$code": "function() {}", - "$scope": {} - }, - "Subdocument": { - "foo": "bar" - }, - "Array": [ - {"$numberInt": "1"}, - {"$numberInt": "2"}, - {"$numberInt": "3"}, - {"$numberInt": "4"}, - {"$numberInt": "5"} - ], - "Timestamp": { - "$timestamp": { "t": 42, "i": 1 } - }, - "RegularExpression": { - "$regularExpression": { - "pattern": "foo*", - "options": "ix" - } - }, - "DatetimeEpoch": { - "$date": { - "$numberLong": "0" - } - }, - "DatetimePositive": { - "$date": { - "$numberLong": "253402300799999" - } - }, - "DatetimeNegative": { - "$date": { - "$numberLong": "-62135596800000" - } - }, - "True": true, - "False": false, - "DBRef": { - "$ref": "collection", - "$id": { - "$oid": "57e193d7a9cc81b4027498b1" - }, - "$db": "database" - }, - "DBRefNoDB": { - "$ref": "collection", - "$id": { - "$oid": "57fd71e96e32ab4225b723fb" - } - }, - "Minkey": { - "$minKey": 1 - }, - "Maxkey": { - "$maxKey": 1 - }, - "Null": null - } - - -Relaxed Extended JSON Example ------------------------------ - -In Relaxed Extended JSON, the example document is transformed similarly -to Canonical Extended JSON, with the exception of the following -keys (newlines and spaces added for readability):: - - { - ... - "Int32": 42, - "Int64": 42, - "Double": 42.42, - ... - "DatetimeEpoch": { - "$date": "1970-01-01T00:00:00.000Z" - }, - ... - } - -Motivation for Change -===================== - -There existed many Extended JSON parser and generator implementations prior to -this specification that used conflicting formats, since there was no agreement -on the precise format of Extended JSON. This resulted in problems where the -output of some generators could not be consumed by some parsers. - -MongoDB drivers needed a single, standard Extended JSON format for testing that -covers all BSON types. However, there were BSON types that had no defined -Extended JSON representation. This spec primarily addresses that need, but -provides for slightly broader use as well. - -Design Rationale -================ - -Of Relaxed and Canonical Formats --------------------------------- - -There are various use cases for expressing BSON documents in a text rather -that binary format. They broadly fall into two categories: - -* Type preserving: for things like testing, where one has to describe the - expected form of a BSON document, it's helpful to be able to precisely - specify expected types. In particular, numeric types need to differentiate - between Int32, Int64 and Double forms. - -* JSON-like: for things like a web API, where one is sending a document (or a - projection of a document) that only uses ordinary JSON type primitives, it's - desirable to represent numbers in the native JSON format. This output is - also the most human readable and is useful for debugging and documentation. +} +``` -The two formats in this specification address these two categories of use cases. +The above document is transformed into the following (newlines and spaces added for readability): -Of Parsers and Generators -------------------------- +```javascript +{ + "_id": { + "$oid": "57e193d7a9cc81b4027498b5" + }, + "String": "string", + "Int32": { + "$numberInt": "42" + }, + "Int64": { + "$numberLong": "42" + }, + "Double": { + "$numberDouble": "42.42" + }, + "Decimal": { + "$numberDecimal": "1234.5" + }, + "Binary": { + "$binary": { + "base64": "yO2rw/c4TKO2jauSqRR4ow==", + "subType": "04" + } + }, + "BinaryUserDefined": { + "$binary": { + "base64": "MTIz", + "subType": "80" + } + }, + "Code": { + "$code": "function() {}" + }, + "CodeWithScope": { + "$code": "function() {}", + "$scope": {} + }, + "Subdocument": { + "foo": "bar" + }, + "Array": [ + {"$numberInt": "1"}, + {"$numberInt": "2"}, + {"$numberInt": "3"}, + {"$numberInt": "4"}, + {"$numberInt": "5"} + ], + "Timestamp": { + "$timestamp": { "t": 42, "i": 1 } + }, + "RegularExpression": { + "$regularExpression": { + "pattern": "foo*", + "options": "ix" + } + }, + "DatetimeEpoch": { + "$date": { + "$numberLong": "0" + } + }, + "DatetimePositive": { + "$date": { + "$numberLong": "253402300799999" + } + }, + "DatetimeNegative": { + "$date": { + "$numberLong": "-62135596800000" + } + }, + "True": true, + "False": false, + "DBRef": { + "$ref": "collection", + "$id": { + "$oid": "57e193d7a9cc81b4027498b1" + }, + "$db": "database" + }, + "DBRefNoDB": { + "$ref": "collection", + "$id": { + "$oid": "57fd71e96e32ab4225b723fb" + } + }, + "Minkey": { + "$minKey": 1 + }, + "Maxkey": { + "$maxKey": 1 + }, + "Null": null +} +``` + +### Relaxed Extended JSON Example + +In Relaxed Extended JSON, the example document is transformed similarly to Canonical Extended JSON, with the exception +of the following keys (newlines and spaces added for readability): + +```javascript +{ + ... + "Int32": 42, + "Int64": 42, + "Double": 42.42, + ... + "DatetimeEpoch": { + "$date": "1970-01-01T00:00:00.000Z" + }, + ... +} +``` -Parsers need to accept any valid Extended JSON string that a generator can -produce. Parsers and generators are permitted to accept and output strings in -other formats as well for backwards compatibility. +## Motivation for Change -.. _levels of nesting: +There existed many Extended JSON parser and generator implementations prior to this specification that used conflicting +formats, since there was no agreement on the precise format of Extended JSON. This resulted in problems where the output +of some generators could not be consumed by some parsers. -Acceptable nesting depth has implications for resource usage so unlimited -nesting is not permitted. +MongoDB drivers needed a single, standard Extended JSON format for testing that covers all BSON types. However, there +were BSON types that had no defined Extended JSON representation. This spec primarily addresses that need, but provides +for slightly broader use as well. -Generators support at least 100 levels of nesting in a BSON document -being transformed to Extended JSON. This aligns with MongoDB's own limitation of -100 levels of nesting. +## Design Rationale -Parsers support at least 200 levels of nesting in Extended JSON text, -since the Extended JSON language can double the level of apparent nesting of a -BSON document by wrapping certain types in their own documents. +### Of Relaxed and Canonical Formats -Of Canonical Type Wrapper Formats ---------------------------------- +There are various use cases for expressing BSON documents in a text rather that binary format. They broadly fall into +two categories: -Prior to this specification, BSON types fell into three categories with respect -to Legacy Extended JSON: +- Type preserving: for things like testing, where one has to describe the expected form of a BSON document, it's helpful + to be able to precisely specify expected types. In particular, numeric types need to differentiate between Int32, + Int64 and Double forms. +- JSON-like: for things like a web API, where one is sending a document (or a projection of a document) that only uses + ordinary JSON type primitives, it's desirable to represent numbers in the native JSON format. This output is also the + most human readable and is useful for debugging and documentation. -1. A single, portable representation for the type already existed. +The two formats in this specification address these two categories of use cases. -2. Multiple representations for the type existed among various Extended JSON - generators, and those representations were in conflict with each other or - with current portability goals. +### Of Parsers and Generators -3. No Legacy Extended JSON representation existed. +Parsers need to accept any valid Extended JSON string that a generator can produce. Parsers and generators are permitted +to accept and output strings in other formats as well for backwards compatibility. -If a BSON type fell into category (1), this specification just declares that -form to be canonical, since all drivers, tools, and libraries already know how -to parse or output this form. There are two exceptions: - -RegularExpression -................. - -The form ``{"$regex: , $options: "}`` has until this -specification been canonical. The change to ``{"$regularExpression": -{pattern: , "options": "}}`` is motivated by a conflict between -the previous canonical form and the ``$regex`` MongoDB query operator. The form -specified here disambiguates between the two, such that a parser can accept any -MongoDB query filter, even one containing the ``$regex`` operator. - -Binary -...... - -The form ``{"$binary": "AQIDBAU=", "$type": "80"}`` has until this specification -been canonical. The change to ``{"$binary": {"base64": "AQIDBAU=", "subType": -"80"}}`` is motivated by a conflict between the previous canonical form and the -``$type`` MongoDB query operator. The form specified here disambiguates between -the two, such that a parser can accept any MongoDB query filter, even one -containing the ``$type`` operator. - -Reconciled type wrappers -........................ - -If a BSON type fell into category (2), this specification selects a new common -representation for the type to be canonical. Conflicting formats were gathered -by surveying a number of Extended JSON generators, including the MongoDB Java -Driver (version 3.3.0), the MongoDB Python Driver (version 3.4.0.dev0), the -MongoDB Extended JSON module on NPM (version 1.7.1), and each minor version of -mongoexport from 2.4.14 through 3.3.12. When possible, we set the "strict" -option on the JSON codec. The following BSON types had conflicting Extended JSON -representations: - -Binary -'''''' - -Some implementations write the Extended JSON form of a Binary object with a -strict two-hexadecimal digit subtype (e.g. they output a leading ``0`` for -subtypes < 16). However, the NPM mongodb-extended-json module and Java driver -use a single hexadecimal digit to represent subtypes less than 16. This -specification makes both one- and two-digit representations acceptable. - -Code -'''' - -Mongoexport 2.4 does not quote the ``Code`` value when writing out the extended -JSON form of a BSON Code object. All other implementations do so. This spec -canonicalises the form where the Javascript code is quoted, since the latter -form adheres to the JSON specification and the former does not. As an -additional note, the NPM mongodb-extended-json module uses the form ``{"code": -""}, omitting the dollar sign (``$``) from the key. This -specification does not accommodate the eccentricity of a single library. - -CodeWithScope -''''''''''''' - -In addition to the same variants as BSON Code types, there are other variations -when turning CodeWithScope objects into Extended JSON. Mongoexport 2.4 and 2.6 -omit the scope portion of CodeWithScope if it is empty, making the output -indistinguishable from a Code type. All other implementations include the empty -scope. This specification therefore canonicalises the form where the scope is -always included. The presence of ``$scope`` is what differentiates Code from -CodeWithScope. +
+ +Acceptable nesting depth has implications for resource usage so unlimited nesting is not permitted. -Datetime -'''''''' +Generators support at least 100 levels of nesting in a BSON document being transformed to Extended JSON. This aligns +with MongoDB's own limitation of 100 levels of nesting. -Mongoexport 2.4 and the Java driver always transform a Datetime object into an -Extended JSON string of the form ``{"$date": }``. This form has -the problem of a potential loss of precision or range on the Datetimes that can -be represented. Mongoexport 2.6 transforms Datetime objects into an extended -JSON string of the form ``{"$date": }`` for -dates starting at or after the Unix epoch (UTC). Dates prior to the epoch take -the form ``{"$date": {"$numberLong": ""}}``. Starting in version -3.0, mongoexport always turns Datetime objects into strings of the form -``{"$date": }``. The NPM mongodb-extended-json -module does the same. The Python driver can also transform Datetime objects into -strings like ``{"$date": {"$numberLong": ""}}``. This -specification canonicalises this form, since this form is the most portable. +Parsers support at least 200 levels of nesting in Extended JSON text, since the Extended JSON language can double the +level of apparent nesting of a BSON document by wrapping certain types in their own documents. -In Relaxed Extended JSON format, this specification provides for ISO-8601 -representation for better readability, but limits it to a portable subset, from -the epoch to the end of the largest year that can be represented with four -digits. This should encompass most typical use of dates in applications. +### Of Canonical Type Wrapper Formats -DBPointer -''''''''' +Prior to this specification, BSON types fell into three categories with respect to Legacy Extended JSON: -Mongoexport 2.4 and 2.6 use the form ``{"$ref": , "$id": }``. All other implementations studied include the canonical ``ObjectId`` -form: ``{"$ref": , "$id": {"$oid": }}``. Neither of these -forms are distinguishable from that of DBRef, so this specification creates a -new format: ``{"$dbPointer": {"$ref": , "$id": {"$oid": }}}``. +1. A single, portable representation for the type already existed. +2. Multiple representations for the type existed among various Extended JSON generators, and those representations were + in conflict with each other or with current portability goals. +3. No Legacy Extended JSON representation existed. -Newly-added type wrappers -......................... +If a BSON type fell into category (1), this specification just declares that form to be canonical, since all drivers, +tools, and libraries already know how to parse or output this form. There are two exceptions: -If a BSON type fell into category (3), above, this specification creates a type -wrapper format for the type. The following new Extended JSON type wrappers are -introduced by this spec: +#### RegularExpression -* ``$dbPointer`` - See above. +The form `{"$regex: , $options: "}` has until this specification been canonical. The change to +`{"$regularExpression": {pattern: , "options": "}}` is motivated by a conflict between the previous +canonical form and the `$regex` MongoDB query operator. The form specified here disambiguates between the two, such that +a parser can accept any MongoDB query filter, even one containing the `$regex` operator. -* ``$numberInt`` - This is used to preserve the "int32" BSON type in Canonical - Extended JSON. Without using ``$numberInt``, this type will be - indistinguishable from a double in certain languages where the distinction - does not exist, such as Javascript. +#### Binary -* ``$numberDouble`` - This is used to preserve the ``double`` type in Canonical - Extended JSON, as some JSON generators might omit a trailing ".0" for - integral types. It also supports representing non-finite values like NaN or - Infinity which are prohibited in the JSON specification for numbers. - -* ``$symbol`` - The use of the ``$symbol`` key preserves the symbol type in - Canonical Extended JSON, distinguishing it from JSON strings. - -Reference Implementation -======================== - -[*Canonical Extended JSON format reference implementation needs to be updated*] - -PyMongo implements the Canonical Extended JSON format, which must be chosen by -selecting the right option on the ``JSONOptions`` object:: - - from bson.json_util import dumps, DatetimeRepresentation, CANONICAL_JSON_OPTIONS - - dumps(document, json_options=CANONICAL_JSON_OPTIONS) - -[*Relaxed Extended JSON format reference implementation is TBD*] - -Implementation Notes -==================== - -JSON File Format ----------------- - -Some applications like mongoexport may wish to write multiple Extended JSON -documents to a single file. One way to do this is to list each JSON document -one-per-line. When doing this, it is important to ensure that special characters -like newlines are encoded properly (e.g. ``\n``). - -Duplicate Keys --------------- - -The BSON specification does not prohibit duplicate key names within the same -BSON document, but provides no semantics for the interpretation of duplicate -keys. The JSON specification says that names within an object should be unique, -and many JSON libraries are incapable of handling this scenario. - -This specification is silent on the matter, so as not to conflict with a future -change by either specification. - -Future Work -=========== - -This specification will need to be amended if future BSON types are added to the -BSON specification. - -Q&A -=== - -**Q**. Why was version 2 of the spec necessary? - -**A**. After Version 1 was released, several stakeholders raised concerns that -not providing an option to output BSON numbers as ordinary JSON numbers limited -the utility of Extended JSON for common historical uses. We decided to provide -a second format option and more clearly distinguish the use cases (and -limitations) inherent in each format. - -**Q**. My BSON parser doesn't distinguish every BSON type. Does my Extended -JSON generator need to distinguish these types? - -**A**. No. Some BSON parsers do not emit a unique type for each BSON type, -making round-tripping BSON through such libraries impossible without changing -the document. For example, a ``DBPointer`` will be parsed into a ``DBRef`` by -PyMongo. In such cases, a generator must emit the Extended JSON form for -whatever type the BSON parser emitted. It does not need to preserve type -information when that information has been lost by the BSON parser. +The form `{"$binary": "AQIDBAU=", "$type": "80"}` has until this specification been canonical. The change to +`{"$binary": {"base64": "AQIDBAU=", "subType": "80"}}` is motivated by a conflict between the previous canonical form +and the `$type` MongoDB query operator. The form specified here disambiguates between the two, such that a parser can +accept any MongoDB query filter, even one containing the `$type` operator. -**Q**. How can implementations which require backwards compatibility with Legacy -Extended JSON, in which BSON regular expressions were represented with -``$regex``, handle parsing of extended JSON test representing a MongoDB query -filter containing the ``$regex`` operator? +#### Reconciled type wrappers -**A**. An implementation can handle this in a number of ways: +If a BSON type fell into category (2), this specification selects a new common representation for the type to be +canonical. Conflicting formats were gathered by surveying a number of Extended JSON generators, including the MongoDB +Java Driver (version 3.3.0), the MongoDB Python Driver (version 3.4.0.dev0), the MongoDB Extended JSON module on NPM +(version 1.7.1), and each minor version of mongoexport from 2.4.14 through 3.3.12. When possible, we set the "strict" +option on the JSON codec. The following BSON types had conflicting Extended JSON representations: -- Introduce an enumeration that determines the behavior of the parser. If the - value is LEGACY, it will parse ``$regex`` and not treat ``$regularExpression`` - specially, and if the value is CANONICAL, it will parse ``$regularExpression`` - and not treat ``$regex`` specially. -- Support both legacy and canonical forms in the parser without requiring the - application to specify one or the other. Making that work for the ``$regex`` - query operator use case will require that the rules set forth in the 1.0.0 - version of this specification are followed for ``$regex``; specifically, that - a document with a ``$regex`` key whose value is a JSON object should be - parsed as a normal document and not reported as an error. +##### Binary -**Q**. How can implementations which require backwards compatibility with Legacy -Extended JSON, in which BSON binary values were represented like ``{"$binary": -"AQIDBAU=", "$type": "80"}``, handle parsing of extended JSON test representing -a MongoDB query filter containing the ``$type`` operator? +Some implementations write the Extended JSON form of a Binary object with a strict two-hexadecimal digit subtype (e.g. +they output a leading `0` for subtypes \< 16). However, the NPM mongodb-extended-json module and Java driver use a +single hexadecimal digit to represent subtypes less than 16. This specification makes both one- and two-digit +representations acceptable. -**A**. An implementation can handle this in a number of ways: +##### Code -- Introduce an enumeration that determines the behavior of the parser. If the - value is LEGACY, it will parse the new binary form and not treat the legacy - one specially, and if the value is CANONICAL, it will parse the new form and - not treat the legacy form specially. -- Support both legacy and canonical forms in the parser without requiring the - application to specify one or the other. Making that work for the ``$type`` - query operator use case will require that the rules set forth in the 1.0.0 - version of this specification are followed for ``$type``; specifically, that - a document with a ``$type`` key whose value is an integral type, or a - document with a ``$type`` key but without a ``$binary`` key, should be - parsed as a normal document and not reported as an error. +Mongoexport 2.4 does not quote the `Code` value when writing out the extended JSON form of a BSON Code object. All other +implementations do so. This spec canonicalises the form where the Javascript code is quoted, since the latter form +adheres to the JSON specification and the former does not. As an additional note, the NPM mongodb-extended-json module +uses the form `{"code": ""}`, omitting the dollar sign (`$`) from the key. This specification does not +accommodate the eccentricity of a single library. -**Q**. Sometimes I see the term "extjson" used in other specifications. Is -"extjson" related to this specification? +##### CodeWithScope + +In addition to the same variants as BSON Code types, there are other variations when turning CodeWithScope objects into +Extended JSON. Mongoexport 2.4 and 2.6 omit the scope portion of CodeWithScope if it is empty, making the output +indistinguishable from a Code type. All other implementations include the empty scope. This specification therefore +canonicalises the form where the scope is always included. The presence of `$scope` is what differentiates Code from +CodeWithScope. +##### Datetime + +Mongoexport 2.4 and the Java driver always transform a Datetime object into an Extended JSON string of the form +`{"$date": }`. This form has the problem of a potential loss of precision or range on the Datetimes that +can be represented. Mongoexport 2.6 transforms Datetime objects into an extended JSON string of the form +`{"$date": }`for dates starting at or after the Unix epoch (UTC). Dates prior to the +epoch take the form `{"$date": {"$numberLong": ""}}`. Starting in version 3.0, mongoexport always turns +Datetime objects into strings of the form `{"$date": }`. The NPM mongodb-extended-json +module does the same. The Python driver can also transform Datetime objects into strings like +`{"$date": {"$numberLong": ""}}`. This specification canonicalises this form, since this form is the +most portable. In Relaxed Extended JSON format, this specification provides for ISO-8601 representation for better +readability, but limits it to a portable subset, from the epoch to the end of the largest year that can be represented +with four digits. This should encompass most typical use of dates in applications. + +##### DBPointer + +Mongoexport 2.4 and 2.6 use the form`{"$ref": , "$id": }`. All other implementations studied +include the canonical `ObjectId` form:`{"$ref": , "$id": {"$oid": }}`. Neither of these forms are +distinguishable from that of DBRef, so this specification creates a new format: +`{"$dbPointer": {"$ref": , "$id": {"$oid": }}}`. + +##### Newly-added type wrappers . + +If a BSON type fell into category (3), above, this specification creates a type wrapper format for the type. The +following new Extended JSON type wrappers are introduced by this spec: + +- `$dbPointer`- See above. +- `$numberInt` - This is used to preserve the "int32" BSON type in Canonical Extended JSON. Without using `$numberInt`, + this type will be indistinguishable from a double in certain languages where the distinction does not exist, such as + Javascript. +- `$numberDouble` - This is used to preserve the `double`type in Canonical Extended JSON, as some JSON generators might + omit a trailing ".0" for integral types.\ + It also supports representing non-finite values like NaN or Infinity which + are prohibited in the JSON specification for numbers. +- `$symbol` - The use of the `$symbol` key preserves the symbol type in Canonical Extended JSON, distinguishing it from + JSON strings. + +### Reference Implementation + +\[*Canonical Extended JSON format reference implementation needs to be updated*\] PyMongo implements the Canonical +Extended JSON format, which must be chosen by selecting the right option on the `JSONOptions` object:: + +```python +from bson.json_util import dumps, DatetimeRepresentation, CANONICAL_JSON_OPTIONS +dumps(document, json_options=CANONICAL_JSON_OPTIONS) +``` + +\[*Relaxed Extended JSON format reference implementation is TBD*\] + +### Implementation Notes + +#### JSON File Format + +Some applications like mongoexport may wish to write multiple Extended JSON documents to a single file. One way to do +this is to list each JSON document one-per-line. When doing this, it is important to ensure that special characters like +newlines are encoded properly (e.g.`n`). + +#### Duplicate Keys + +The BSON specification does not prohibit duplicate key names within the same BSON document, but provides no semantics +for the interpretation of duplicate keys. The JSON specification says that names within an object should be unique, and +many JSON libraries are incapable of handling this scenario. This specification is silent on the matter, so as not to +conflict with a future change by either specification. + +### Future Work + +This specification will need to be amended if future BSON types are added to the BSON specification. + +## Q&A + +**Q**. Why was version 2 of the spec necessary? **A**. After Version 1 was released, several stakeholders raised +concerns that not providing an option to output BSON numbers as ordinary JSON numbers limited the utility of Extended +JSON for common historical uses. We decided to provide a second format option and more clearly distinguish the use cases +(and limitations) inherent in each format. + +**Q**. My BSON parser doesn't distinguish every BSON type. Does my Extended JSON generator need to distinguish these +types?\ +**A**. No. Some BSON parsers do not emit a unique type for each BSON type, making round-tripping BSON through +such libraries impossible without changing the document. For example, a `DBPointer` will be parsed into a `DBRef` by +PyMongo. In such cases, a generator must emit the Extended JSON form for whatever type the BSON parser emitted. It does +not need to preserve type information when that information has been lost by the BSON parser. + +**Q**. How can implementations which require backwards compatibility with Legacy Extended JSON, in which BSON regular +expressions were represented with `$regex`, handle parsing of extended JSON test representing a MongoDB query filter +containing the `$regex` operator?\ +**A**. An implementation can handle this in a number of ways: - Introduce an +enumeration that determines the behavior of the parser. If the value is LEGACY, it will parse `$regex`and not treat +`$regularExpression` specially, and if the value is CANONICAL, it will parse `$regularExpression` and not treat `$regex` +specially. - Support both legacy and canonical forms in the parser without requiring the application to specify one or +the other. Making that work for the `$regex` query operator use case will require that the rules set forth in the 1.0.0 +version of this specification are followed for `$regex`; specifically, that a document with a `$regex` key whose value +is a JSON object should be parsed as a normal document and not reported as an error. + +**Q**. How can implementations which require backwards compatibility with Legacy Extended JSON, in which BSON binary +values were represented like `{"$binary": "AQIDBAU=", "$type": "80"}`, handle parsing of extended JSON test representing +a MongoDB query filter containing the `$type`operator?\ +**A**. An implementation can handle this in a number of ways:\ +\- +Introduce an enumeration that determines the behavior of the parser. If the value is LEGACY, it will parse the new +binary form and not treat the legacy one specially, and if the value is CANONICAL, it will parse the new form and not +treat the legacy form specially. - Support both legacy and canonical forms in the parser without requiring the +application to specify one or the other. Making that work for the `$type` query operator use case will require that the +rules set forth in the 1.0.0 version of this specification are followed for `$type`; specifically, that a document with +a `$type` key whose value is an integral type, or a document with a `$type` key but without a `$binary` key, should be +parsed as a normal document and not reported as an error. + +**Q**. Sometimes I see the term "extjson" used in other specifications. Is "extjson" related to this +specification?\ **A**. Yes, "extjson" is short for "Extended JSON". -Changelog -========= - -:2022-10-05: Remove spec front matter and reformat changelog. -:2021-05-26: * Remove any mention of extra dollar-prefixed keys being prohibited - in a DBRef. MongoDB 5.0 and compatible drivers no longer enforce - such restrictions. - * Objects that resemble a DBRef without fully complying to its - structure should be left as-is during parsing. -:2020-09-01: Note that ``$``-prefixed keys not matching a known type MUST be - left as-is when parsing. This is patch-level change as this - behavior was already required in the BSON corpus tests ("Document - with keys that start with $"). -:2020-09-08: * Added support for parsing ``$uuid`` fields as BSON Binary subtype 4. - * Changed the example to using the MongoDB Python Driver. It - previously used the MongoDB Java Driver. The new example excludes - the following BSON types that are unsupported in Python - - ``Symbol``, ``SpecialFloat``, ``DBPointer`` and ``Undefined``. - Transformations for these types are now only documented in the - `Conversion table`_. -:2017-07-20: * Bumped specification to version 2.0. - * Added "Relaxed" format. - * Changed BSON timestamp type wrapper back to - ``{"t": *int*, "i": *int*}`` for backwards compatibility. (The - change in v1 to unsigned 64-bit string was premature optimization) - * Changed BSON regular expression type wrapper to - ``{"$regularExpression": {pattern: *string*, "options": *string*"}}``. - * Changed BSON binary type wrapper to ``{"$binary": {"base64": , "subType": }}`` - * Added "Restrictions and limitations" section. - * Clarified parser and generator rules. -:2017-02-01: Initial specification version 1.0. +### Changelog + +- 2024-05-29: Migrated from reStructuredText to Markdown. +- 2022-10-05: Remove spec front matter and reformat changelog. +- 2021-05-26: + - Remove any mention of extra dollar-prefixed keys being prohibited in a DBRef. MongoDB 5.0 and compatible drivers no + longer enforce such restrictions. + - Objects that resemble a DBRef without fully complying to its structure should be left as-is during parsing. - + 2020-09-01: Note that `$`-prefixed keys not matching a known type MUST be left as-is when parsing. This is + patch-level change as this behavior was already required in the BSON corpus tests ("Document with keys that start + with $"). +- 2020-09-08: + - Added support for parsing `$uuid` fields as BSON Binary subtype 4. + - Changed the example to using the MongoDB Python Driver. It previously used the MongoDB Java Driver. The new example + excludes the following BSON types that are unsupported in Python - `Symbol`,`SpecialFloat`,`DBPointer`, and + `Undefined`. Transformations for these types are now only documented in the `Conversion table`\_. +- 2017-07-20: + - Bumped specification to version 2.0. + - Added "Relaxed" format. + - Changed BSON timestamp type wrapper back to `{"t": *int*, "i": *int*}` for backwards compatibility. (The change in + v1 to unsigned 64-bit string was premature optimization) + - Changed BSON regular expression type wrapper to `{"$regularExpression": {pattern: *string*, "options": *string*"}}`. + - Changed BSON binary type wrapper to + `{"$binary": {"base64": , "subType": }}` + - Added "Restrictions and limitations" section. + - Clarified parser and generator rules. +- 2017-02-01: Initial specification version 1.0. + +[^1]: This MUST conform to the [Decimal128 specification](./bson-decimal128/decimal128.md#writing-to-extended-json) + +[^2]: BSON Regular Expression options MUST be in alphabetical order. + +[^3]: See [the docs manual](https://www.mongodb.com/docs/manual/reference/glossary/#term-namespace) + +[^4]: See [https://tools.ietf.org/html/rfc3339#section-5.6](https://tools.ietf.org/html/rfc3339#section-5.6) + +[^5]: Fractional seconds SHOULD have exactly 3 decimal places if the fractional part is non-zero. Otherwise, fractional + seconds SHOULD be omitted if zero. + +[^6]: See [the docs manual](https://www.mongodb.com/docs/manual/reference/database-references/#dbrefs) diff --git a/source/extended-json.rst b/source/extended-json.rst new file mode 100644 index 0000000000..fc32e1d430 --- /dev/null +++ b/source/extended-json.rst @@ -0,0 +1,4 @@ + +.. note:: + This specification has been converted to Markdown and renamed to + `extended-json.md `_. diff --git a/source/gridfs/tests/README.md b/source/gridfs/tests/README.md index 6418f3ec31..8285b2e306 100644 --- a/source/gridfs/tests/README.md +++ b/source/gridfs/tests/README.md @@ -12,7 +12,7 @@ GridFS. These tests utilize the [Unified Test Format](../../unified-test-format/ The unified test format allows binary stream data to be expressed and matched with `$$hexBytes` (for uploads) and `$$matchesHexBytes` (for downloads), respectively; however, those operators are not supported in all contexts, such as `insertData` and `outcome`. When binary data must be expressed as a base64-encoded string -([Extended JSON](../../extended-json.rst) for a BSON binary type), the test SHOULD include a comment noting the +([Extended JSON](../../extended-json.md) for a BSON binary type), the test SHOULD include a comment noting the equivalent value in hexadecimal for human-readability. For example: ```yaml diff --git a/source/index.md b/source/index.md index b2145622db..38db825d55 100644 --- a/source/index.md +++ b/source/index.md @@ -16,6 +16,7 @@ - [Driver Mantras](./driver-mantras.md) - [Driver Sessions Specification](sessions/driver-sessions.md) - [Driver Transactions Specification](transactions/transactions.md) +- [Extended JSON](./extended-json.md) - [FaaS Automated Testing](faas-automated-testing/faas-automated-testing.md) - [GridFS Spec](gridfs/gridfs-spec.md) - [Handling of DBRefs](./dbref.md) diff --git a/source/unified-test-format/unified-test-format.md b/source/unified-test-format/unified-test-format.md index 302961b599..689e281353 100644 --- a/source/unified-test-format/unified-test-format.md +++ b/source/unified-test-format/unified-test-format.md @@ -2634,7 +2634,7 @@ Note: the test runner is not required to validate the type or value of a `$$plac ### Evaluating Matches Expected values in tests (e.g. [operation.expectResult](#operation_expectResult)) are expressed as either relaxed or -canonical [Extended JSON](../extended-json.rst). +canonical [Extended JSON](../extended-json.md). The algorithm for matching expected and actual values is specified with the following pseudo-code: @@ -2680,7 +2680,7 @@ The rules for comparing documents and arrays are discussed in more detail in sub *other* than documents and arrays, test runners MAY adopt any of the following approaches to compare expected and actual values, as long as they are consistent: -- Convert both values to relaxed or canonical [Extended JSON](../extended-json.rst) and compare strings +- Convert both values to relaxed or canonical [Extended JSON](../extended-json.md) and compare strings - Convert both values to BSON, and compare bytes - Convert both values to native representations, and compare accordingly @@ -3015,8 +3015,8 @@ tests. The instructions in this section apply for each test file loaded by the test runner. -Test files, which may be YAML or JSON files, MUST be interpreted using an [Extended JSON](../extended-json.rst) parser. -The parser MUST accept relaxed and canonical Extended JSON (per [Extended JSON: Parsers](../extended-json.rst#parsers)), +Test files, which may be YAML or JSON files, MUST be interpreted using an [Extended JSON](../extended-json.md) parser. +The parser MUST accept relaxed and canonical Extended JSON (per [Extended JSON: Parsers](../extended-json.md#parsers)), as test files may use either. Upon loading a file, the test runner MUST read the [schemaVersion](#schemaVersion) field and determine if the test file