Possible solution for tags generation

docs/api-guide/schemas.md

@@ -215,6 +215,81 @@ This also applies to extra actions for `ViewSet`s:
 If you wish to provide a base `AutoSchema` subclass to be used throughout your
 project you may adjust `settings.DEFAULT_SCHEMA_CLASS`  appropriately.
 
+
+### Grouping Operations With Tags
+
+Tags can be used to group logical operations. Each tag name in the list MUST be unique. 
+
+---
+#### Django REST Framework generates tags automatically with the following logic:
+
+Tag name will be first element from the path. Also, any `_` in path name will be replaced by a `-`.
+Consider below examples.
+
+Example 1: Consider a user management system. The following table will illustrate the tag generation logic.
+Here first element from the paths is: `users`. Hence tag wil be `users`
+
+Http Method                          |        Path       |     Tags
+-------------------------------------|-------------------|-------------
+PUT, PATCH, GET(Retrieve), DELETE    |     /users/{id}/  |   ['users']
+POST, GET(List)                      |     /users/       |   ['users']
+
+Example 2: Consider a restaurant management system. The System has restaurants. Each restaurant has branches.
+Consider REST APIs to deal with a branch of a particular restaurant.
+Here first element from the paths is: `restaurants`. Hence tag wil be `restaurants`.
+
+Http Method                          |                         Path                       |     Tags
+-------------------------------------|----------------------------------------------------|-------------------
+PUT, PATCH, GET(Retrieve), DELETE:   | /restaurants/{restaurant_id}/branches/{branch_id}  |   ['restaurants']
+POST, GET(List):                     | /restaurants/{restaurant_id}/branches/             |   ['restaurants']
+
+Example 3: Consider Order items for an e commerce company.
+
+Http Method                          |          Path           |     Tags
+-------------------------------------|-------------------------|-------------
+PUT, PATCH, GET(Retrieve), DELETE    |     /order_items/{id}/  |   ['order-items']
+POST, GET(List)                      |     /order_items/       |   ['order-items']
+
+
+---
+#### Overriding auto generated tags:
+You can override auto-generated tags by passing `tags` argument to the constructor of `AutoSchema`. `tags` argument must be a list or tuple of string.
+```python
+from rest_framework.schemas.openapi import AutoSchema
+from rest_framework.views import APIView
+
+class MyView(APIView):
+    schema = AutoSchema(tags=['tag1', 'tag2'])
+    ...
+```
+
+If you need more customization, you can override the `get_tags` method of `AutoSchema` class. Consider the following example:
+
+```python
+from rest_framework.schemas.openapi import AutoSchema
+from rest_framework.views import APIView
+
+class MySchema(AutoSchema):
+    ...
+    def get_tags(self, path, method):
+        if method == 'POST':
+            tags = ['tag1', 'tag2']
+        elif method == 'GET':
+            tags = ['tag2', 'tag3'] 
+        elif path == '/example/path/':
+            tags = ['tag3', 'tag4']
+        else:
+            tags = ['tag5', 'tag6', 'tag7']
+
+        return tags
+
+class MyView(APIView):
+    schema = MySchema()
+    ...
+```
+
+
 [openapi]: https://github.com/OAI/OpenAPI-Specification
 [openapi-specification-extensions]: https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#specification-extensions
 [openapi-operation]: https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#operationObject
+[openapi-tags]: https://swagger.io/specification/#tagObject

rest_framework/schemas/openapi.py

@@ -71,6 +71,12 @@ def get_schema(self, request=None, public=False):
 
 class AutoSchema(ViewInspector):
 
+    def __init__(self, tags=None):
+        if tags and not all(isinstance(tag, str) for tag in tags):
+            raise ValueError('tags must be a list or tuple of string.')
+        self._tags = tags
+        super().__init__()
+
     request_media_types = []
     response_media_types = []
 
@@ -98,6 +104,7 @@ def get_operation(self, path, method):
         if request_body:
             operation['requestBody'] = request_body
         operation['responses'] = self._get_responses(path, method)
+        operation['tags'] = self.get_tags(path, method)
 
         return operation
 
@@ -564,3 +571,16 @@ def _get_responses(self, path, method):
                 'description': ""
             }
         }
+
+    def get_tags(self, path, method):
+        # If user have specified tags, use them.
+        if self._tags:
+            return self._tags
+
+        # First element of a specific path could be valid tag. This is a fallback solution.
+        # PUT, PATCH, GET(Retrieve), DELETE:        /user_profile/{id}/       tags = [user-profile]
+        # POST, GET(List):                          /user_profile/            tags = [user-profile]
+        if path.startswith('/'):
+            path = path[1:]
+
+        return [path.split('/')[0].replace('_', '-')]

tests/schemas/test_openapi.py

@@ -126,6 +126,7 @@ def test_path_without_parameters(self):
             'operationId': 'listDocStringExamples',
             'description': 'A description of my GET operation.',
             'parameters': [],
+            'tags': ['example'],
             'responses': {
                 '200': {
                     'description': '',
@@ -166,6 +167,7 @@ def test_path_with_id_parameter(self):
                     'type': 'string',
                 },
             }],
+            'tags': ['example'],
             'responses': {
                 '200': {
                     'description': '',
@@ -696,6 +698,55 @@ def test_serializer_validators(self):
         assert properties['ip']['type'] == 'string'
         assert 'format' not in properties['ip']
 
+    def test_overridden_tags(self):
+        class ExampleStringTagsViewSet(views.ExampleGenericAPIView):
+            schema = AutoSchema(tags=['example1', 'example2'])
+
+        url_patterns = [
+            url(r'^test/?$', ExampleStringTagsViewSet.as_view()),
+        ]
+        generator = SchemaGenerator(patterns=url_patterns)
+        schema = generator.get_schema(request=create_request('/'))
+        assert schema['paths']['/test/']['get']['tags'] == ['example1', 'example2']
+
+    def test_overridden_get_tags_method(self):
+        class MySchema(AutoSchema):
+            def get_tags(self, path, method):
+                if path.endswith('/new/'):
+                    tags = ['tag1', 'tag2']
+                elif path.endswith('/old/'):
+                    tags = ['tag2', 'tag3']
+                else:
+                    tags = ['tag4', 'tag5']
+
+                return tags
+
+        class ExampleStringTagsViewSet(views.ExampleGenericViewSet):
+            schema = MySchema()
+
+        router = routers.SimpleRouter()
+        router.register('example', ExampleStringTagsViewSet, basename="example")
+        generator = SchemaGenerator(patterns=router.urls)
+        schema = generator.get_schema(request=create_request('/'))
+        assert schema['paths']['/example/new/']['get']['tags'] == ['tag1', 'tag2']
+        assert schema['paths']['/example/old/']['get']['tags'] == ['tag2', 'tag3']
+
+    def test_auto_generated_apiview_tags(self):
+        class RestaurantAPIView(views.ExampleGenericAPIView):
+            pass
+
+        class BranchAPIView(views.ExampleGenericAPIView):
+            pass
+
+        url_patterns = [
+            url(r'^any-dash_underscore/?$', RestaurantAPIView.as_view()),
+            url(r'^restaurants/branches/?$', BranchAPIView.as_view())
+        ]
+        generator = SchemaGenerator(patterns=url_patterns)
+        schema = generator.get_schema(request=create_request('/'))
+        assert schema['paths']['/any-dash_underscore/']['get']['tags'] == ['any-dash-underscore']
+        assert schema['paths']['/restaurants/branches/']['get']['tags'] == ['restaurants']
+
 
 @pytest.mark.skipif(uritemplate is None, reason='uritemplate not installed.')
 @override_settings(REST_FRAMEWORK={'DEFAULT_SCHEMA_CLASS': 'rest_framework.schemas.openapi.AutoSchema'})