Add support for generic unions

RELEASE.md

@@ -0,0 +1,3 @@
+Release type: patch
+
+Attempt to merge union types during schema conversion.

strawberry/schema/name_converter.py

@@ -107,8 +107,14 @@ def from_union(self, union: StrawberryUnion) -> str:
  return union.graphql_name
 
  name = ""
+ types = union.types
 
- for type_ in union.types:
+ if union.concrete_of and union.concrete_of.graphql_name:
+ concrete_of_types = set(union.concrete_of.types)
+
+ types = [type_ for type_ in types if type_ not in concrete_of_types]
+
+ for type_ in types:
  if isinstance(type_, LazyType):
  type_ = cast("StrawberryType", type_.resolve_type()) # noqa: PLW2901
 
@@ -121,6 +127,9 @@ def from_union(self, union: StrawberryUnion) -> str:
 
  name += type_name
 
+ if union.concrete_of and union.concrete_of.graphql_name:
+ name += union.concrete_of.graphql_name
+
  return name
 
  def from_generic(
@@ -133,12 +142,12 @@ def from_generic(
  names: List[str] = []
 
  for type_ in types:
- name = self.get_from_type(type_)
+ name = self.get_name_from_type(type_)
  names.append(name)
 
  return "".join(names) + generic_type_name
 
- def get_from_type(self, type_: Union[StrawberryType, type]) -> str:
+ def get_name_from_type(self, type_: Union[StrawberryType, type]) -> str:
  type_ = eval_type(type_)
 
  if isinstance(type_, LazyType):
@@ -148,9 +157,9 @@ def get_from_type(self, type_: Union[StrawberryType, type]) -> str:
  elif isinstance(type_, StrawberryUnion):
  name = type_.graphql_name if type_.graphql_name else self.from_union(type_)
  elif isinstance(type_, StrawberryList):
- name = self.get_from_type(type_.of_type) + "List"
+ name = self.get_name_from_type(type_.of_type) + "List"
  elif isinstance(type_, StrawberryOptional):
- name = self.get_from_type(type_.of_type) + "Optional"
+ name = self.get_name_from_type(type_.of_type) + "Optional"
  elif hasattr(type_, "_scalar_definition"):
  strawberry_type = type_._scalar_definition
 

strawberry/schema/schema_converter.py

@@ -851,14 +851,20 @@ def from_union(self, union: StrawberryUnion) -> GraphQLUnionType:
  return graphql_union
 
  graphql_types: List[GraphQLObjectType] = []
+
  for type_ in union.types:
  graphql_type = self.from_type(type_)
 
  if isinstance(graphql_type, GraphQLInputObjectType):
  raise InvalidTypeInputForUnion(graphql_type)
- assert isinstance(graphql_type, GraphQLObjectType)
+ assert isinstance(graphql_type, (GraphQLObjectType, GraphQLUnionType))
 
- graphql_types.append(graphql_type)
+ # If the graphql_type is a GraphQLUnionType, merge its child types
+ if isinstance(graphql_type, GraphQLUnionType):
+ # Add the child types of the GraphQLUnionType to the list of graphql_types
+ graphql_types.extend(graphql_type.types)
+ else:
+ graphql_types.append(graphql_type)
 
  graphql_union = GraphQLUnionType(
  name=union_name,

strawberry/union.py

@@ -67,6 +67,7 @@ def __init__(
  self.directives = directives
  self._source_file = None
  self._source_line = None
+ self.concrete_of: Optional[StrawberryUnion] = None
 
  def __eq__(self, other: object) -> bool:
  if isinstance(other, StrawberryType):
@@ -139,6 +140,7 @@ def copy_with(
  return self
 
  new_types = []
+
  for type_ in self.types:
  new_type: Union[StrawberryType, type]
 
@@ -154,10 +156,13 @@ def copy_with(
 
  new_types.append(new_type)
 
- return StrawberryUnion(
+ new_union = StrawberryUnion(
  type_annotations=tuple(map(StrawberryAnnotation, new_types)),
  description=self.description,
  )
+ new_union.concrete_of = self
+
+ return new_union
 
  def __call__(self, *args: str, **kwargs: Any) -> NoReturn:
  """Do not use.

tests/schema/test_union.py

@@ -856,3 +856,115 @@
 
  assert not result.errors
  assert result.data["something"] == {"__typename": "A", "a": 5}
+
+
+def test_generic_union_with_annotated():
+ @strawberry.type
+ class SomeType:
+ id: strawberry.ID
+ name: str
+
+ @strawberry.type
+ class NotFoundError:
+ id: strawberry.ID
+ message: str
+
+ T = TypeVar("T")
+
+ @strawberry.type
+ class ObjectQueries(Generic[T]):
+ @strawberry.field
+ def by_id(
+ self, id: strawberry.ID
+ ) -> Annotated[Union[T, NotFoundError], strawberry.union("ByIdResult")]: ...
+
+ @strawberry.type
+ class Query:
+ @strawberry.field
+ def some_type_queries(self, id: strawberry.ID) -> ObjectQueries[SomeType]:
+ raise NotImplementedError()
+
+ schema = strawberry.Schema(Query)
+
+ assert (
+ str(schema)
+ == textwrap.dedent(
+ """
+ type NotFoundError {
+ id: ID!
+ message: String!
+ }
+
+ type Query {
+ someTypeQueries(id: ID!): SomeTypeObjectQueries!
+ }
+
+ type SomeType {
+ id: ID!
+ name: String!
+ }
+
+ union SomeTypeByIdResult = SomeType | NotFoundError
+
+ type SomeTypeObjectQueries {
+ byId(id: ID!): SomeTypeByIdResult!
+ }
+ """
+ ).strip()
+ )
+
+
+def test_generic_union_with_annotated_inside():
+ @strawberry.type
+ class SomeType:
+ id: strawberry.ID
+ name: str
+
+ @strawberry.type
+ class NotFoundError:
+ id: strawberry.ID
+ message: str
+
+ T = TypeVar("T")
+
+ @strawberry.type
+ class ObjectQueries(Generic[T]):
+ @strawberry.field
+ def by_id(
+ self, id: strawberry.ID
+ ) -> Union[T, Annotated[NotFoundError, strawberry.union("ByIdResult")]]: ...
+
+ @strawberry.type
+ class Query:
+ @strawberry.field
+ def some_type_queries(self, id: strawberry.ID) -> ObjectQueries[SomeType]:
+ return ObjectQueries(SomeType)
+
+ schema = strawberry.Schema(Query)
+
+ assert (
+ str(schema)
+ == textwrap.dedent(
+ """
+ type NotFoundError {
+ id: ID!
+ message: String!
+ }
+
+ type Query {
+ someTypeQueries(id: ID!): SomeTypeObjectQueries!
+ }
+
+ type SomeType {
+ id: ID!
+ name: String!
+ }
+
+ union SomeTypeByIdResult = SomeType | NotFoundError
+
+ type SomeTypeObjectQueries {
+ byId(id: ID!): SomeTypeByIdResult!
+ }
+ """
+ ).strip()
+ )