minor fix

bson/bsonrw/extjson_writer.go

@@ -33,18 +33,17 @@ type extJSONValueWriter struct {
 	frame      int64
 	canonical  bool
 	escapeHTML bool
-	newlines   bool
 }
 
 // NewExtJSONValueWriter creates a ValueWriter that writes Extended JSON to w.
 func NewExtJSONValueWriter(w io.Writer, canonical, escapeHTML bool) ValueWriter {
 	// Enable newlines for all Extended JSON value writers created by NewExtJSONValueWriter. We
 	// expect these value writers to be used with an Encoder, which should add newlines after
 	// encoded Extended JSON documents.
-	return newExtJSONWriter(w, canonical, escapeHTML, false)
+	return newExtJSONWriter(w, canonical, escapeHTML)
 }
 
-func newExtJSONWriter(w io.Writer, canonical, escapeHTML, newlines bool) *extJSONValueWriter {
+func newExtJSONWriter(w io.Writer, canonical, escapeHTML bool) *extJSONValueWriter {
 	stack := make([]ejvwState, 1, 5)
 	stack[0] = ejvwState{mode: mTopLevel}
 
@@ -54,7 +53,6 @@ func newExtJSONWriter(w io.Writer, canonical, escapeHTML, newlines bool) *extJSO
 		stack:      stack,
 		canonical:  canonical,
 		escapeHTML: escapeHTML,
-		newlines:   newlines,
 	}
 }
 
@@ -504,12 +502,6 @@ func (ejvw *extJSONValueWriter) WriteDocumentEnd() error {
 	case mDocument:
 		ejvw.buf = append(ejvw.buf, ',')
 	case mTopLevel:
-		// If the value writer has newlines enabled, end top-level documents with a newline so that
-		// multiple documents encoded to the same writer are separated by newlines. That matches the
-		// Go json.Encoder behavior and also works with bsonrw.NewExtJSONValueReader.
-		if ejvw.newlines {
-			ejvw.buf = append(ejvw.buf, '\n')
-		}
 		if ejvw.w != nil {
 			if _, err := ejvw.w.Write(ejvw.buf); err != nil {
 				return err

bson/bsonrw/extjson_writer_test.go

@@ -139,7 +139,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 				t.Fatalf("fn must have one return value and it must be an error.")
 			}
 			params := make([]reflect.Value, 1, len(tc.params)+1)
-			ejvw := newExtJSONWriter(io.Discard, true, true, false)
+			ejvw := newExtJSONWriter(io.Discard, true, true)
 			params[0] = reflect.ValueOf(ejvw)
 			for _, param := range tc.params {
 				params = append(params, reflect.ValueOf(param))
@@ -162,7 +162,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 	}
 
 	t.Run("WriteArray", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mArray, parent: mTopLevel,
 			name: "WriteArray", modes: []mode{mElement, mValue}, action: "write"}
@@ -172,7 +172,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteCodeWithScope", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mCodeWithScope, parent: mTopLevel,
 			name: "WriteCodeWithScope", modes: []mode{mElement, mValue}, action: "write"}
@@ -182,7 +182,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocument", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mDocument, parent: mTopLevel,
 			name: "WriteDocument", modes: []mode{mElement, mValue, mTopLevel}, action: "write"}
@@ -192,7 +192,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocumentElement", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mElement)
 		want := TransitionError{current: mElement,
 			destination: mElement,
@@ -206,7 +206,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocumentEnd", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mElement)
 		want := fmt.Errorf("incorrect mode to end document: %s", mElement)
 		got := ejvw.WriteDocumentEnd()
@@ -215,7 +215,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteArrayElement", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mElement)
 		want := TransitionError{current: mElement,
 			destination: mValue,
@@ -229,7 +229,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteArrayEnd", func(t *testing.T) {
-		ejvw := newExtJSONWriter(io.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true)
 		ejvw.push(mElement)
 		want := fmt.Errorf("incorrect mode to end array: %s", mElement)
 		got := ejvw.WriteArrayEnd()

bson/bsonrw/value_writer.go

@@ -138,6 +138,15 @@ func NewValueWriter(w io.Writer) ValueWriter {
 	return newValueWriter(w)
 }
 
+// NewValueWriterFlusher retrieves a ValueWriterFlusher.
+//
+// Deprecated: NewValueWriterFlusher will not be supported in Go Driver 2.0.
+func NewValueWriterFlusher(w io.Writer) ValueWriterFlusher {
+	vw := newValueWriter(w)
+	vw.push(mElement)
+	return vw
+}
+
 func newValueWriter(w io.Writer) *valueWriter {
 	vw := new(valueWriter)
 	stack := make([]vwState, 1, 5)

bson/marshal.go

@@ -73,17 +73,23 @@ func MarshalValue(val interface{}) (bsontype.Type, []byte, error) {
 // Driver 2.0.
 func MarshalValueWithRegistry(r *bsoncodec.Registry, val interface{}) (bsontype.Type, []byte, error) {
 	sw := bsonrw.SliceWriter(make([]byte, 0))
-	vw := bsonrw.NewValueWriter(&sw)
+	vwFlusher := bsonrw.NewValueWriterFlusher(&sw)
 
 	// get an Encoder and encode the value
 	enc := encPool.Get().(*Encoder)
 	defer encPool.Put(enc)
-	enc.Reset(vw)
+	enc.Reset(vwFlusher)
 	enc.ec = bsoncodec.EncodeContext{Registry: r}
 	if err := enc.Encode(val); err != nil {
 		return 0, nil, err
 	}
 
+	// flush the bytes written because we cannot guarantee that a full document has been written
+	// after the flush, *sw will be in the format
+	// [value type, 0 (null byte to indicate end of empty element name), value bytes..]
+	if err := vwFlusher.Flush(); err != nil {
+		return 0, nil, err
+	}
 	return bsontype.Type(sw[0]), sw[2:], nil
 }