401 lines
19 KiB
ReStructuredText
401 lines
19 KiB
ReStructuredText
.. |br| raw:: html
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<br />
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########################
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Custom schema generation
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########################
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If the default spec generation does not quite match what you were hoping to achieve, ``drf-yasg`` provides some
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custom behavior hooks by default.
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*********************
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Swagger spec overview
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*********************
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This library generates OpenAPI 2.0 documents. The authoritative specification for this document's structure will always
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be the official documentation over at `swagger.io <https://swagger.io/>`__ and the `OpenAPI 2.0 specification
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page <https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md>`__.
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Beause the above specifications are a bit heavy and convoluted, here is a general overview of how the specification
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is structured, starting from the root ``Swagger`` object.
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* :class:`.Swagger` object
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+ ``info``, ``schemes``, ``securityDefinitions`` and other informative attributes
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+ ``paths``: :class:`.Paths` object
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A list of all the paths in the API in the form of a mapping
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- ``{path}``: :class:`.PathItem` - each :class:`.PathItem` has multiple operations keyed by method
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* ``{http_method}``: :class:`.Operation`
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Each operation is thus uniquely identified by its ``(path, http_method)`` combination,
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e.g. ``GET /articles/``, ``POST /articles/``, etc.
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* ``parameters``: [:class:`.Parameter`] - and a list of path parameters
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+ ``definitions``: named Models
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A list of all the named models in the API in the form of a mapping
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- ``{ModelName}``: :class:`.Schema`
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* :class:`.Operation` contains the following information about each operation:
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+ ``parameters``: [:class:`.Parameter`]
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A list of all the *query*, *header* and *form* parameters accepted by the operation.
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- there can also be **at most one** body parameter whose structure is represented by a
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:class:`.Schema` or a reference to one (:class:`.SchemaRef`)
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+ ``responses``: :class:`.Responses`
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A list of all the possible responses the operation is expected to return. Each response can optionally have a
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:class:`.Schema` which describes the structure of its body.
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- ``{status_code}``: :class:`.Response` - mapping of status code to response definition
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+ ``operationId`` - should be unique across all operations
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+ ``tags`` - used to group operations in the listing
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It is interesting to note the main differences between :class:`.Parameter` and :class:`.Schema` objects:
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+----------------------------------------------------------+-----------------------------------------------------------+
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| :class:`.Schema` | :class:`.Parameter` |
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+==========================================================+===========================================================+
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| Can nest other Schemas | Cannot nest other Parameters |br| |
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| | Can only nest a Schema if the parameter is ``in: body`` |
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+----------------------------------------------------------+-----------------------------------------------------------+
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| Cannot describe file uploads |br| | Can describe file uploads via ``type`` = ``file``, |br| |
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| - ``file`` is not permitted as a value for ``type`` | but only as part of a form :class:`.Operation` [#formop]_ |
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+----------------------------------------------------------+-----------------------------------------------------------+
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| Can be used in :class:`.Response`\ s | Cannot be used in :class:`.Response`\ s |
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+----------------------------------------------------------+-----------------------------------------------------------+
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| Cannot be used in form :class:`.Operation`\ s [#formop]_ | Can be used in form :class:`.Operation`\ s [#formop]_ |
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+----------------------------------------------------------+-----------------------------------------------------------+
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| Can only describe request or response bodies | Can describe ``query``, ``form``, ``header`` or ``path`` |
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| | parameters |
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+----------------------------------------------------------+-----------------------------------------------------------+
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.. [#formop] a form Operation is an :class:`.Operation` that consumes ``multipart/form-data`` or
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``application/x-www-form-urlencoded`` content
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* a form Operation cannot have ``body`` parameters
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* a non-form operation cannot have ``form`` parameters
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****************
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Default behavior
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****************
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This section describes where information is sourced from when using the default generation process.
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* :class:`.Paths` are generated by exploring the patterns registered in your default ``urlconf``, or the ``patterns``
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and ``urlconf`` you specified when constructing :class:`.OpenAPISchemaGenerator`; only views inheriting from Django
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Rest Framework's ``APIView`` are looked at, all other views are ignored
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* ``path`` :class:`.Parameter`\ s are generated by looking in the URL pattern for any template parameters; attempts are
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made to guess their type from the views ``queryset`` and ``lookup_field``, if applicable. You can override path
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parameters via ``manual_parameters`` in :ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>`.
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* ``query`` :class:`.Parameter`\ s - i.e. parameters specified in the URL as ``/path/?query1=value&query2=value`` -
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are generated from your view's ``filter_backends`` and ``paginator``, if any are declared. Additional parameters can
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be specified via the ``query_serializer`` and ``manual_parameters`` arguments of
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:ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>`
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* The request body is only generated for the HTTP ``POST``, ``PUT`` and ``PATCH`` methods, and is sourced from the
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view's ``serializer_class``. You can also override the request body using the ``request_body`` argument of
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:ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>`.
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- if the view represents a form request (that is, all its parsers are of the ``multipart/form-data`` or
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``application/x-www-form-urlencoded`` media types), the request body will be output as ``form``
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:class:`.Parameter`\ s
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- if it is not a form request, the request body will be output as a single ``body`` :class:`.Parameter` wrapped
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around a :class:`.Schema`
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* ``header`` :class:`.Parameter`\ s are supported by the OpenAPI specification but are never generated by this library;
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you can still add them using ``manual_parameters``.
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* :class:`.Responses` are generated as follows:
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+ if ``responses`` is provided to :ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>` and contains at least
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one success status code (i.e. any `2xx` status code), no automatic response is generated and the given response
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is used as described in the :func:`@swagger_auto_schema documentation <.swagger_auto_schema>`
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+ otherwise, an attempt is made to generate a default response:
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- the success status code is assumed to be ``204` for ``DELETE`` requests, ``201`` for ``POST`` requests, and
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``200`` for all other request methods
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- if the view has a request body, the same ``Serializer`` or :class:`.Schema` as in the request body is used
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in generating the :class:`.Response` schema; this is inline with the default ``GenericAPIView`` and
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``GenericViewSet`` behavior
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- if the view has no request body, its ``serializer_class`` is used to generate the :class:`.Response` schema
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- if the view is a list view (as defined by :func:`.is_list_view`), the response schema is wrapped in an array
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- if the view is also paginated, the response schema is then wrapped in the appropriate paging response structure
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- the description of the response is left blank
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* :class:`.Response` headers are supported by the OpenAPI specification but not currently supported by this library;
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you can still add them manually by providing an `appropriately structured dictionary
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<https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#headersObject>`_
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to the ``headers`` property of a :class:`.Response` object
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* *descriptions* for :class:`.Operation`\ s, :class:`.Parameter`\ s and :class:`.Schema`\ s are picked up from
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docstrings and ``help_text`` attributes in the same manner as the `default DRF SchemaGenerator
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<http://www.django-rest-framework.org/api-guide/schemas/#schemas-as-documentation>`_
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.. _custom-spec-swagger-auto-schema:
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**************************************
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The ``@swagger_auto_schema`` decorator
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**************************************
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You can use the :func:`@swagger_auto_schema <.swagger_auto_schema>` decorator on view functions to override
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some properties of the generated :class:`.Operation`. For example, in a ``ViewSet``,
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.. code:: python
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@swagger_auto_schema(operation_description="partial_update description override", responses={404: 'slug not found'})
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def partial_update(self, request, *args, **kwargs):
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"""partial_update method docstring"""
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...
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will override the description of the ``PATCH /article/{id}/`` operation, and document a 404 response with no body and
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the given description.
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Where you can use the :func:`@swagger_auto_schema <.swagger_auto_schema>` decorator depends on the type of your view:
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* for function based ``@api_view``\ s, because the same view can handle multiple methods, and thus represent multiple
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operations, you have to add the decorator multiple times if you want to override different operations:
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.. code:: python
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test_param = openapi.Parameter('test', openapi.IN_QUERY, description="test manual param", type=openapi.TYPE_BOOLEAN)
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user_response = openapi.Response('response description', UserSerializer)
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# 'method' can be used to customize a single HTTP method of a view
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@swagger_auto_schema(method='get', manual_parameters=[test_param], responses={200: user_response})
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# 'methods' can be used to apply the same modification to multiple methods
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@swagger_auto_schema(methods=['put', 'post'], request_body=UserSerializer)
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@api_view(['GET', 'PUT', 'POST'])
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def user_detail(request, pk):
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...
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* for class based ``APIView``, ``GenericAPIView`` and non-``ViewSet`` derivatives, you have to decorate the respective
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method of each operation:
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.. code:: python
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class UserList(APIView):
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@swagger_auto_schema(responses={200: UserSerializer(many=True)})
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def get(self, request):
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...
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@swagger_auto_schema(operation_description="description")
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def post(self, request):
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...
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* for ``ViewSet``, ``GenericViewSet``, ``ModelViewSet``, because each viewset corresponds to multiple **paths**, you have
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to decorate the *action methods*, i.e. ``list``, ``create``, ``retrieve``, etc. |br|
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Additionally, ``@list_route``\ s or ``@detail_route``\ s defined on the viewset, like function based api views, can
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respond to multiple HTTP methods and thus have multiple operations that must be decorated separately:
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.. code:: python
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class ArticleViewSet(viewsets.ModelViewSet):
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# method or 'methods' can be skipped because the list_route only handles a single method (GET)
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@swagger_auto_schema(operation_description='GET /articles/today/')
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@list_route(methods=['get'])
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def today(self, request):
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...
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@swagger_auto_schema(method='get', operation_description="GET /articles/{id}/image/")
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@swagger_auto_schema(method='post', operation_description="POST /articles/{id}/image/")
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@detail_route(methods=['get', 'post'], parser_classes=(MultiPartParser,))
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def image(self, request, id=None):
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...
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@swagger_auto_schema(operation_description="PUT /articles/{id}/")
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def update(self, request, *args, **kwargs):
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...
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@swagger_auto_schema(operation_description="PATCH /articles/{id}/")
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def partial_update(self, request, *args, **kwargs):
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...
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.. Tip::
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If you want to customize the generation of a method you are not implementing yourself, you can use
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``swagger_auto_schema`` in combination with Django's ``method_decorator``:
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.. code:: python
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@method_decorator(name='list', decorator=swagger_auto_schema(
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operation_description="description from swagger_auto_schema via method_decorator"
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))
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class ArticleViewSet(viewsets.ModelViewSet):
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...
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This allows you to avoid unnecessarily overriding the method.
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.. Tip::
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You can go even further and directly decorate the result of ``as_view``, in the same manner you would
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override an ``@api_view`` as described above:
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.. code:: python
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decorated_login_view = \
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swagger_auto_schema(
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method='post',
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responses={status.HTTP_200_OK: LoginResponseSerializer}
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)(LoginView.as_view())
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urlpatterns = [
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...
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url(r'^login/$', decorated_login_view, name='login')
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]
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This can allow you to avoid skipping an unnecessary *subclass* altogether.
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.. Warning::
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However, do note that both of the methods above can lead to unexpected (and maybe surprising) results by
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replacing/decorating methods on the base class itself.
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********************************
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Serializer ``Meta`` nested class
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********************************
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You can define some per-serializer options by adding a ``Meta`` class to your serializer, e.g.:
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.. code:: python
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class WhateverSerializer(Serializer):
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...
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class Meta:
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... options here ...
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Currently, the only option you can add here is
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* ``ref_name`` - a string which will be used as the model definition name for this serializer class; setting it to
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``None`` will force the serializer to be generated as an inline model everywhere it is used
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*************************
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Subclassing and extending
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*************************
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---------------------
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``SwaggerAutoSchema``
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---------------------
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For more advanced control you can subclass :class:`~.inspectors.SwaggerAutoSchema` - see the documentation page
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for a list of methods you can override.
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You can put your custom subclass to use by setting it on a view method using the
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:ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>` decorator described above, by setting it as a
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class-level attribute named ``swagger_schema`` on the view class, or
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:ref:`globally via settings <default-class-settings>`.
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For example, to generate all operation IDs as camel case, you could do:
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.. code:: python
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from inflection import camelize
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class CamelCaseOperationIDAutoSchema(SwaggerAutoSchema):
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def get_operation_id(self, operation_keys):
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operation_id = super(CamelCaseOperationIDAutoSchema, self).get_operation_id(operation_keys)
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return camelize(operation_id, uppercase_first_letter=False)
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SWAGGER_SETTINGS = {
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'DEFAULT_AUTO_SCHEMA_CLASS': 'path.to.CamelCaseOperationIDAutoSchema',
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...
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}
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--------------------------
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``OpenAPISchemaGenerator``
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--------------------------
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If you need to control things at a higher level than :class:`.Operation` objects (e.g. overall document structure,
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vendor extensions in metadata) you can also subclass :class:`.OpenAPISchemaGenerator` - again, see the documentation
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page for a list of its methods.
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This custom generator can be put to use by setting it as the :attr:`.generator_class` of a :class:`.SchemaView` using
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:func:`.get_schema_view`.
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.. _custom-spec-inspectors:
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---------------------
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``Inspector`` classes
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---------------------
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.. versionadded:: 1.1
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For customizing behavior related to specific field, serializer, filter or paginator classes you can implement the
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:class:`~.inspectors.FieldInspector`, :class:`~.inspectors.SerializerInspector`, :class:`~.inspectors.FilterInspector`,
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:class:`~.inspectors.PaginatorInspector` classes and use them with
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:ref:`@swagger_auto_schema <custom-spec-swagger-auto-schema>` or one of the
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:ref:`related settings <default-class-settings>`.
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A :class:`~.inspectors.FilterInspector` that adds a description to all ``DjangoFilterBackend`` parameters could be
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implemented like so:
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.. code:: python
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class DjangoFilterDescriptionInspector(CoreAPICompatInspector):
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def get_filter_parameters(self, filter_backend):
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if isinstance(filter_backend, DjangoFilterBackend):
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result = super(DjangoFilterDescriptionInspector, self).get_filter_parameters(filter_backend)
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for param in result:
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if not param.get('description', ''):
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param.description = "Filter the returned list by {field_name}".format(field_name=param.name)
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return result
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return NotHandled
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@method_decorator(name='list', decorator=swagger_auto_schema(
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filter_inspectors=[DjangoFilterDescriptionInspector]
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))
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class ArticleViewSet(viewsets.ModelViewSet):
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filter_backends = (DjangoFilterBackend,)
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filter_fields = ('title',)
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...
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A second example, of a :class:`~.inspectors.FieldInspector` that removes the ``title`` attribute from all generated
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:class:`.Schema` objects:
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.. code:: python
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class NoSchemaTitleInspector(FieldInspector):
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def process_result(self, result, method_name, obj, **kwargs):
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# remove the `title` attribute of all Schema objects
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if isinstance(result, openapi.Schema.OR_REF):
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# traverse any references and alter the Schema object in place
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schema = openapi.resolve_ref(result, self.components)
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schema.pop('title', None)
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# no ``return schema`` here, because it would mean we always generate
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# an inline `object` instead of a definition reference
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# return back the same object that we got - i.e. a reference if we got a reference
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return result
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class NoTitleAutoSchema(SwaggerAutoSchema):
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field_inspectors = [NoSchemaTitleInspector] + swagger_settings.DEFAULT_FIELD_INSPECTORS
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class ArticleViewSet(viewsets.ModelViewSet):
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swagger_schema = NoTitleAutoSchema
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...
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.. Note::
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A note on references - :class:`.Schema` objects are sometimes output by reference (:class:`.SchemaRef`); in fact,
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that is how named models are implemented in OpenAPI:
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- in the output swagger document there is a ``definitions`` section containing :class:`.Schema` objects for all
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models
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- every usage of a model refers to that single :class:`.Schema` object - for example, in the ArticleViewSet
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above, all requests and responses containg an ``Article`` model would refer to the same schema definition by a
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``'$ref': '#/definitions/Article'``
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This is implemented by only generating **one** :class:`.Schema` object for every serializer **class** encountered.
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This means that you should generally avoid view or method-specific ``FieldInspector``\ s if you are dealing with
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references (a.k.a named models), because you can never know which view will be the first to generate the schema
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for a given serializer.
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