.. |br| raw:: html
########################
Custom schema generation
########################
If the default spec generation does not quite match what you were hoping to achieve, ``drf-yasg`` provides some
custom behavior hooks by default.
.. _custom-spec-excluding-endpoints:
*******************
Excluding endpoints
*******************
You can prevent a view from being included in the Swagger view by setting its class-level ``swagger_schema``
attribute to ``None``, or you can prevent an operation from being included by setting its ``auto_schema`` override
to none in :ref:`@swagger_auto_schema `:
.. code-block:: python
class UserList(APIView):
swagger_schema = None
# all methods of the UserList class will be excluded
...
# only the GET method will be shown in Swagger
@swagger_auto_schema(method='put', auto_schema=None)
@swagger_auto_schema(methods=['get'], ...)
@api_view(['GET', 'PUT'])
def user_detail(request, pk):
pass
.. _custom-spec-swagger-auto-schema:
**************************************
The ``@swagger_auto_schema`` decorator
**************************************
You can use the :func:`@swagger_auto_schema <.swagger_auto_schema>` decorator on view functions to override
some properties of the generated :class:`.Operation`. For example, in a ``ViewSet``,
.. code-block:: python
@swagger_auto_schema(operation_description="partial_update description override", responses={404: 'slug not found'})
def partial_update(self, request, *args, **kwargs):
"""partial_update method docstring"""
...
will override the description of the ``PATCH /article/{id}/`` operation, and document a 404 response with no body and
the given description.
Where you can use the :func:`@swagger_auto_schema <.swagger_auto_schema>` decorator depends on the type of your view:
* for function based ``@api_view``\ s, because the same view can handle multiple methods, and thus represent multiple
operations, you have to add the decorator multiple times if you want to override different operations:
.. code-block:: python
test_param = openapi.Parameter('test', openapi.IN_QUERY, description="test manual param", type=openapi.TYPE_BOOLEAN)
user_response = openapi.Response('response description', UserSerializer)
# 'method' can be used to customize a single HTTP method of a view
@swagger_auto_schema(method='get', manual_parameters=[test_param], responses={200: user_response})
# 'methods' can be used to apply the same modification to multiple methods
@swagger_auto_schema(methods=['put', 'post'], request_body=UserSerializer)
@api_view(['GET', 'PUT', 'POST'])
def user_detail(request, pk):
...
* for class based ``APIView``, ``GenericAPIView`` and non-``ViewSet`` derivatives, you have to decorate the respective
method of each operation:
.. code-block:: python
class UserList(APIView):
@swagger_auto_schema(responses={200: UserSerializer(many=True)})
def get(self, request):
...
@swagger_auto_schema(operation_description="description")
def post(self, request):
...
* for ``ViewSet``, ``GenericViewSet``, ``ModelViewSet``, because each viewset corresponds to multiple **paths**, you have
to decorate the *action methods*, i.e. ``list``, ``create``, ``retrieve``, etc. |br|
Additionally, ``@action``\ s defined on the viewset, like function based api views, can respond to multiple HTTP
methods and thus have multiple operations that must be decorated separately:
.. code-block:: python
class ArticleViewSet(viewsets.ModelViewSet):
# method or 'methods' can be skipped because the action only handles a single method (GET)
@swagger_auto_schema(operation_description='GET /articles/today/')
@action(detail=False, methods=['get'])
def today(self, request):
...
@swagger_auto_schema(method='get', operation_description="GET /articles/{id}/image/")
@swagger_auto_schema(method='post', operation_description="POST /articles/{id}/image/")
@action(detail=True, methods=['get', 'post'], parser_classes=(MultiPartParser,))
def image(self, request, id=None):
...
@swagger_auto_schema(operation_description="PUT /articles/{id}/")
def update(self, request, *args, **kwargs):
...
@swagger_auto_schema(operation_description="PATCH /articles/{id}/")
def partial_update(self, request, *args, **kwargs):
...
.. Tip::
If you want to customize the generation of a method you are not implementing yourself, you can use
``swagger_auto_schema`` in combination with Django's ``method_decorator``:
.. code-block:: python
@method_decorator(name='list', decorator=swagger_auto_schema(
operation_description="description from swagger_auto_schema via method_decorator"
))
class ArticleViewSet(viewsets.ModelViewSet):
...
This allows you to avoid unnecessarily overriding the method.
.. Tip::
You can go even further and directly decorate the result of ``as_view``, in the same manner you would
override an ``@api_view`` as described above:
.. code-block:: python
decorated_login_view = \
swagger_auto_schema(
method='post',
responses={status.HTTP_200_OK: LoginResponseSerializer}
)(LoginView.as_view())
urlpatterns = [
...
url(r'^login/$', decorated_login_view, name='login')
]
This can allow you to avoid skipping an unnecessary *subclass* altogether.
.. Warning::
However, do note that both of the methods above can lead to unexpected (and maybe surprising) results by
replacing/decorating methods on the base class itself.
*********************************
Support for SerializerMethodField
*********************************
Schema generation of ``serializers.SerializerMethodField`` is supported in two ways:
1) The :func:`swagger_serializer_method <.swagger_serializer_method>` decorator for the use case where the serializer
method is using a serializer. e.g.:
.. code-block:: python
from drf_yasg.utils import swagger_serializer_method
class OtherStuffSerializer(serializers.Serializer):
foo = serializers.CharField()
class ParentSerializer(serializers.Serializer):
other_stuff = serializers.SerializerMethodField()
@swagger_serializer_method(serializer_or_field=OtherStuffSerializer)
def get_other_stuff(self, obj):
return OtherStuffSerializer().data
Note that the ``serializer_or_field`` parameter can accept either a subclass or an instance of ``serializers.Field``.
2) For simple cases where the method is returning one of the supported types, `Python 3 type hinting`_ of the
serializer method return value can be used. e.g.:
.. code-block:: python
class SomeSerializer(serializers.Serializer):
some_number = serializers.SerializerMethodField()
def get_some_number(self, obj) -> float:
return 1.0
When return type hinting is not supported, the equivalent ``serializers.Field`` subclass can be used with
:func:`swagger_serializer_method <.swagger_serializer_method>`:
.. code-block:: python
class SomeSerializer(serializers.Serializer):
some_number = serializers.SerializerMethodField()
@swagger_serializer_method(serializer_or_field=serializers.FloatField)
def get_some_number(self, obj):
return 1.0
********************************
Serializer ``Meta`` nested class
********************************
You can define some per-serializer options by adding a ``Meta`` class to your serializer, e.g.:
.. code-block:: python
class WhateverSerializer(Serializer):
...
class Meta:
... options here ...
.. _swagger_schema_fields:
The available options are:
* ``ref_name`` - a string which will be used as the model definition name for this serializer class; setting it to
``None`` will force the serializer to be generated as an inline model everywhere it is used. If two serializers
have the same ``ref_name``, both their usages will be replaced with a reference to the same definition.
If this option is not specified, all serializers have an implicit name derived from their class name, minus any
``Serializer`` suffix (e.g. ``UserSerializer`` -> ``User``, ``SerializerWithSuffix`` -> ``SerializerWithSuffix``)
* ``swagger_schema_fields`` - a dictionary mapping :class:`.Schema` field names to values. These attributes
will be set on the :class:`.Schema` object generated from the ``Serializer``. Field names must be python values,
which are converted to Swagger ``Schema`` attribute names according to :func:`.make_swagger_name`.
Attribute names and values must conform to the `OpenAPI 2.0 specification `_.
*************************
Subclassing and extending
*************************
---------------------
``SwaggerAutoSchema``
---------------------
For more advanced control you can subclass :class:`~.inspectors.SwaggerAutoSchema` - see the documentation page
for a list of methods you can override.
You can put your custom subclass to use by setting it on a view method using the
:ref:`@swagger_auto_schema ` decorator described above, by setting it as a
class-level attribute named ``swagger_schema`` on the view class, or
:ref:`globally via settings `.
For example, to generate all operation IDs as camel case, you could do:
.. code-block:: python
from inflection import camelize
class CamelCaseOperationIDAutoSchema(SwaggerAutoSchema):
def get_operation_id(self, operation_keys):
operation_id = super(CamelCaseOperationIDAutoSchema, self).get_operation_id(operation_keys)
return camelize(operation_id, uppercase_first_letter=False)
SWAGGER_SETTINGS = {
'DEFAULT_AUTO_SCHEMA_CLASS': 'path.to.CamelCaseOperationIDAutoSchema',
...
}
--------------------------
``OpenAPISchemaGenerator``
--------------------------
If you need to control things at a higher level than :class:`.Operation` objects (e.g. overall document structure,
vendor extensions in metadata) you can also subclass :class:`.OpenAPISchemaGenerator` - again, see the documentation
page for a list of its methods.
This custom generator can be put to use by setting it as the :attr:`.generator_class` of a :class:`.SchemaView` using
:func:`.get_schema_view`.
.. _custom-spec-inspectors:
---------------------
``Inspector`` classes
---------------------
For customizing behavior related to specific field, serializer, filter or paginator classes you can implement the
:class:`~.inspectors.FieldInspector`, :class:`~.inspectors.SerializerInspector`, :class:`~.inspectors.FilterInspector`,
:class:`~.inspectors.PaginatorInspector` classes and use them with
:ref:`@swagger_auto_schema ` or one of the
:ref:`related settings `.
A :class:`~.inspectors.FilterInspector` that adds a description to all ``DjangoFilterBackend`` parameters could be
implemented like so:
.. code-block:: python
class DjangoFilterDescriptionInspector(CoreAPICompatInspector):
def get_filter_parameters(self, filter_backend):
if isinstance(filter_backend, DjangoFilterBackend):
result = super(DjangoFilterDescriptionInspector, self).get_filter_parameters(filter_backend)
for param in result:
if not param.get('description', ''):
param.description = "Filter the returned list by {field_name}".format(field_name=param.name)
return result
return NotHandled
@method_decorator(name='list', decorator=swagger_auto_schema(
filter_inspectors=[DjangoFilterDescriptionInspector]
))
class ArticleViewSet(viewsets.ModelViewSet):
filter_backends = (DjangoFilterBackend,)
filterset_fields = ('title',)
...
A second example, of a :class:`~.inspectors.FieldInspector` that removes the ``title`` attribute from all generated
:class:`.Schema` objects:
.. code-block:: python
class NoSchemaTitleInspector(FieldInspector):
def process_result(self, result, method_name, obj, **kwargs):
# remove the `title` attribute of all Schema objects
if isinstance(result, openapi.Schema.OR_REF):
# traverse any references and alter the Schema object in place
schema = openapi.resolve_ref(result, self.components)
schema.pop('title', None)
# no ``return schema`` here, because it would mean we always generate
# an inline `object` instead of a definition reference
# return back the same object that we got - i.e. a reference if we got a reference
return result
class NoTitleAutoSchema(SwaggerAutoSchema):
field_inspectors = [NoSchemaTitleInspector] + swagger_settings.DEFAULT_FIELD_INSPECTORS
class ArticleViewSet(viewsets.ModelViewSet):
swagger_schema = NoTitleAutoSchema
...
.. Note::
A note on references - :class:`.Schema` objects are sometimes output by reference (:class:`.SchemaRef`); in fact,
that is how named models are implemented in OpenAPI:
- in the output swagger document there is a ``definitions`` section containing :class:`.Schema` objects for all
models
- every usage of a model refers to that single :class:`.Schema` object - for example, in the ArticleViewSet
above, all requests and responses containg an ``Article`` model would refer to the same schema definition by a
``'$ref': '#/definitions/Article'``
This is implemented by only generating **one** :class:`.Schema` object for every serializer **class** encountered.
This means that you should generally avoid view or method-specific ``FieldInspector``\ s if you are dealing with
references (a.k.a named models), because you can never know which view will be the first to generate the schema
for a given serializer.
**IMPORTANT:** nested fields on ``ModelSerializer``\ s that are generated from model ``ForeignKeys`` will always be
output by value. If you want the by-reference behaviour you have to explictly set the serializer class of nested
fields instead of letting ``ModelSerializer`` generate one automatically; for example:
.. code-block:: python
class OneSerializer(serializers.ModelSerializer):
class Meta:
model = SomeModel
fields = ('id',)
class AnotherSerializer(serializers.ModelSerializer):
child = OneSerializer()
class Meta:
model = SomeParentModel
fields = ('id', 'child')
Another caveat that stems from this is that any serializer named "``NestedSerializer``" will be forced inline
unless it has a ``ref_name`` set explicitly.
.. _Python 3 type hinting: https://docs.python.org/3/library/typing.html