OAS 3.0 schema generation (#772)

initial implementation of OAS 3.0 generateschema

Co-authored-by: Alan Crosswell <alan@columbia.edu>
Co-authored-by: Oliver Sauder <sliverc@users.noreply.github.com>

AUTHORS

@@ -14,6 +14,7 @@ Jason Housley <housleyjk@gmail.com>
 Jerel Unruh <mail@unruhdesigns.com>
 Jonathan Senecal <contact@jonathansenecal.com>
 Joseba Mendivil <git@jma.email>
+Kieran Evans <keyz182@gmail.com>
 Léo S. <leo@naeka.fr>
 Luc Cary <luc.cary@gmail.com>
 Matt Layman <https://www.mattlayman.com>

CHANGELOG.md

@@ -18,9 +18,17 @@ This release is not backwards compatible. For easy migration best upgrade first
 * Added support for Django REST framework 3.12
 * Added support for Django 3.1
 * Added support for Python 3.9
+* Added initial optional support for [openapi](https://www.openapis.org/) schema generation. Enable with:
+  ```
+  pip install djangorestframework-jsonapi['openapi']
+  ```
+  This first release is a start at implementing OAS schema generation. To use the generated schema you may
+  still need to manually add some schema attributes but can expect future improvements here and as
+  upstream DRF's OAS schema generation continues to mature.
 
 ### Removed
 
+
 * Removed support for Python 3.5.
 * Removed support for Django 1.11.
 * Removed support for Django 2.1.

README.rst

@@ -108,6 +108,7 @@ From PyPI
     $ # for optional package integrations
     $ pip install djangorestframework-jsonapi['django-filter']
     $ pip install djangorestframework-jsonapi['django-polymorphic']
+    $ pip install djangorestframework-jsonapi['openapi']
 
 
 From Source
@@ -135,7 +136,10 @@ installed and activated:
     $ django-admin loaddata drf_example --settings=example.settings
     $ django-admin runserver --settings=example.settings
 
-Browse to http://localhost:8000
+Browse to
+* http://localhost:8000 for the list of available collections (in a non-JSONAPI format!),
+* http://localhost:8000/swagger-ui/ for a Swagger user interface to the dynamic schema view, or
+* http://localhost:8000/openapi for the schema view's OpenAPI specification document.
 
 
 Running Tests and linting

docs/getting-started.md

@@ -67,6 +67,7 @@ From PyPI
     # for optional package integrations
     pip install djangorestframework-jsonapi['django-filter']
     pip install djangorestframework-jsonapi['django-polymorphic']
+    pip install djangorestframework-jsonapi['openapi']
 
 From Source
 
@@ -85,7 +86,10 @@ From Source
 	django-admin runserver --settings=example.settings
 
 
-Browse to http://localhost:8000
+Browse to
+* [http://localhost:8000](http://localhost:8000) for the list of available collections (in a non-JSONAPI format!),
+* [http://localhost:8000/swagger-ui/](http://localhost:8000/swagger-ui/) for a Swagger user interface to the dynamic schema view, or
+* [http://localhost:8000/openapi](http://localhost:8000/openapi) for the schema view's OpenAPI specification document.
 
 ## Running Tests
 

docs/usage.md

@@ -1,4 +1,3 @@
-
 # Usage
 
 The DJA package implements a custom renderer, parser, exception handler, query filter backends, and
@@ -32,6 +31,7 @@ REST_FRAMEWORK = {
         'rest_framework.renderers.BrowsableAPIRenderer'
     ),
     'DEFAULT_METADATA_CLASS': 'rest_framework_json_api.metadata.JSONAPIMetadata',
+    'DEFAULT_SCHEMA_CLASS': 'rest_framework_json_api.schemas.openapi.AutoSchema',
     'DEFAULT_FILTER_BACKENDS': (
         'rest_framework_json_api.filters.QueryParameterValidationFilter',
         'rest_framework_json_api.filters.OrderingFilter',
@@ -944,3 +944,124 @@ The `prefetch_related` case will issue 4 queries, but they will be small and fas
 ### Relationships
 ### Errors
 -->
+
+## Generating an OpenAPI Specification (OAS) 3.0 schema document
+
+DRF >= 3.12 has a [new OAS schema functionality](https://www.django-rest-framework.org/api-guide/schemas/) to generate an
+[OAS 3.0 schema](https://www.openapis.org/) as a YAML or JSON file.
+
+DJA extends DRF's schema support to generate an OAS schema in the JSON:API format.
+
+### AutoSchema Settings
+
+In order to produce an OAS schema that properly represents the JSON:API structure
+you have to either add a `schema` attribute to each view class or set the `REST_FRAMEWORK['DEFAULT_SCHEMA_CLASS']`
+to DJA's version of AutoSchema.
+
+#### View-based
+
+```python
+from rest_framework_json_api.schemas.openapi import AutoSchema
+
+class MyViewset(ModelViewSet):
+    schema = AutoSchema
+    ...
+```
+
+#### Default schema class
+
+```python
+REST_FRAMEWORK = {
+    # ...
+    'DEFAULT_SCHEMA_CLASS': 'rest_framework_json_api.schemas.openapi.AutoSchema',
+}
+```
+
+### Adding additional OAS schema content
+
+You can extend the OAS schema document by subclassing
+[`SchemaGenerator`](https://www.django-rest-framework.org/api-guide/schemas/#schemagenerator)
+and extending `get_schema`.
+
+
+Here's an example that adds OAS `info` and `servers` objects.
+
+```python
+from rest_framework_json_api.schemas.openapi import SchemaGenerator as JSONAPISchemaGenerator
+
+
+class MySchemaGenerator(JSONAPISchemaGenerator):
+    """
+    Describe my OAS schema info in detail (overriding what DRF put in) and list the servers where it can be found.
+    """
+    def get_schema(self, request, public):
+        schema = super().get_schema(request, public)
+        schema['info'] = {
+            'version': '1.0',
+            'title': 'my demo API',
+            'description': 'A demonstration of [OAS 3.0](https://www.openapis.org)',
+            'contact': {
+                'name': 'my name'
+            },
+            'license': {
+                'name': 'BSD 2 clause',
+                'url': 'https://github.com/django-json-api/django-rest-framework-json-api/blob/master/LICENSE',
+            }
+        }
+        schema['servers'] = [
+            {'url': 'https://localhost/v1', 'description': 'local docker'},
+            {'url': 'http://localhost:8000/v1', 'description': 'local dev'},
+            {'url': 'https://api.example.com/v1', 'description': 'demo server'},
+            {'url': '{serverURL}', 'description': 'provide your server URL',
+             'variables': {'serverURL': {'default': 'http://localhost:8000/v1'}}}
+        ]
+        return schema
+```
+
+### Generate a Static Schema on Command Line
+
+See [DRF documentation for generateschema](https://www.django-rest-framework.org/api-guide/schemas/#generating-a-static-schema-with-the-generateschema-management-command)
+To generate an OAS schema document, use something like:
+
+```text
+$ django-admin generateschema --settings=example.settings \
+                              --generator_class myapp.views.MySchemaGenerator >myschema.yaml
+```
+
+You can then use any number of OAS tools such as
+[swagger-ui-watcher](https://www.npmjs.com/package/swagger-ui-watcher)
+to render the schema:
+```text
+$ swagger-ui-watcher myschema.yaml
+```
+
+Note: Swagger-ui-watcher will complain that "DELETE operations cannot have a requestBody"
+but it will still work. This [error](https://github.com/OAI/OpenAPI-Specification/pull/2117)
+in the OAS specification will be fixed when [OAS 3.1.0](https://www.openapis.org/blog/2020/06/18/openapi-3-1-0-rc0-its-here)
+is published.
+
+([swagger-ui](https://www.npmjs.com/package/swagger-ui) will work silently.)
+
+### Generate a Dynamic Schema in a View
+
+See [DRF documentation for a Dynamic Schema](https://www.django-rest-framework.org/api-guide/schemas/#generating-a-dynamic-schema-with-schemaview).
+
+```python
+from rest_framework.schemas import get_schema_view
+
+urlpatterns = [
+    ...
+    path('openapi', get_schema_view(
+        title="Example API",
+        description="API for all things …",
+        version="1.0.0",
+        generator_class=MySchemaGenerator,
+    ), name='openapi-schema'),
+    path('swagger-ui/', TemplateView.as_view(
+        template_name='swagger-ui.html',
+        extra_context={'schema_url': 'openapi-schema'}
+    ), name='swagger-ui'),
+    ...
+]
+```
+

example/serializers.py

@@ -230,6 +230,16 @@ class AuthorSerializer(serializers.ModelSerializer):
         queryset=Comment.objects,
         many=True
     )
+    secrets = serializers.HiddenField(
+        default='Shhhh!'
+    )
+    defaults = serializers.CharField(
+        default='default',
+        max_length=20,
+        min_length=3,
+        write_only=True,
+        help_text='help for defaults',
+    )
     included_serializers = {
         'bio': AuthorBioSerializer,
         'type': AuthorTypeSerializer
@@ -244,7 +254,8 @@ class AuthorSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = Author
-        fields = ('name', 'email', 'bio', 'entries', 'comments', 'first_entry', 'type')
+        fields = ('name', 'email', 'bio', 'entries', 'comments', 'first_entry', 'type',
+                  'secrets', 'defaults')
 
     def get_first_entry(self, obj):
         return obj.entries.first()

example/settings/dev.py

@@ -21,6 +21,7 @@
     'django.contrib.sites',
     'django.contrib.sessions',
     'django.contrib.auth',
+    'rest_framework_json_api',
     'rest_framework',
     'polymorphic',
     'example',
@@ -88,6 +89,7 @@
         'rest_framework.renderers.BrowsableAPIRenderer',
     ),
     'DEFAULT_METADATA_CLASS': 'rest_framework_json_api.metadata.JSONAPIMetadata',
+    'DEFAULT_SCHEMA_CLASS': 'rest_framework_json_api.schemas.openapi.AutoSchema',
     'DEFAULT_FILTER_BACKENDS': (
         'rest_framework_json_api.filters.OrderingFilter',
         'rest_framework_json_api.django_filters.DjangoFilterBackend',

example/templates/swagger-ui.html

@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Swagger</title>
+    <meta charset="utf-8"/>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link rel="stylesheet" type="text/css" href="//unpkg.com/swagger-ui-dist@3/swagger-ui.css" />
+  </head>
+  <body>
+    <div id="swagger-ui"></div>
+    <script src="//unpkg.com/swagger-ui-dist@3/swagger-ui-bundle.js"></script>
+    <script>
+    const ui = SwaggerUIBundle({
+        url: "{% url schema_url %}",
+        dom_id: '#swagger-ui',
+        presets: [
+          SwaggerUIBundle.presets.apis,
+          SwaggerUIBundle.SwaggerUIStandalonePreset
+        ],
+        layout: "BaseLayout",
+        requestInterceptor: (request) => {
+          request.headers['X-CSRFToken'] = "{{ csrf_token }}"
+          return request;
+        }
+      })
+    </script>
+  </body>
+</html>