Generate schema for Django rest framework viewset actions

Question

As per the DRF documentation I started using ViewSet and have implemented list, retrieve, create, update and destroyactions. I have another APIView for which I was able to write schema (ManualSchema) and when I navigate to /docs/ I am able to the documentation as well as live endpoint for interaction.

I wish to create separate schema for each of the viewset action. I tried writing one but it doesn't show up so I think I am missing something.

Here is the code:

class Clients(viewsets.ViewSet):

    '''

        Clients is DRF viewset which implements `create`, `update`, `read` actions by implementing create, update, list and retrieve functions respectively.

    '''
    list_schema = schemas.ManualSchema(fields=[
            coreapi.Field(
                'status',
                required=False,
                location='query',
                description='Accepted values are `active`, `inactive`'
            ),          
        ], 
        description='Clients list',
        encoding='application/x-www-form-urlencoded')

    @action(detail=True, schema=list_schema)
    def list(self, request):

        '''Logic for listing'''


    def retrieve(self, request, oid=None):

        '''Logic for retrieval'''


    create_schema = schemas.ManualSchema(fields=[
            coreapi.Field(
                'name',
                required=False,
                location='body',
            ),
            coreapi.Field(
                'location',
                required=False,
                location='body',
            ),              
        ], 
        description='Clients list',
        encoding='application/x-www-form-urlencoded')

    @action(detail=True, schema=create_schema)
    def create(self, request):

        '''Logic for creation'''

Answer 1

So I will answer my own question. I took a look at DRF source code for schema generation. I came up with the plan and performed following steps.

I subclassed SchemaGenerator class defined in rest_framework.schemas module. Below is the code.

class CoreAPISchemaGenerator(SchemaGenerator):

    def get_links(self, request=None, **kwargs):

        links = LinkNode()

        paths = list()
        view_endpoints = list()

        for path, method, callback in self.endpoints:
            view = self.create_view(callback, method, request)
            path = self.coerce_path(path, method, view)
            paths.append(path)
            view_endpoints.append((path, method, view))

        if not paths:
            return None

        prefix = self.determine_path_prefix(paths)

        for path, method, view in view_endpoints:

            if not self.has_view_permissions(path, method, view):
                continue

            actions = getattr(view, 'actions', None)
            schemas = getattr(view, 'schemas', None)

            if not schemas:

                link = view.schema.get_link(path, method, base_url=self.url)
                subpath = path[len(prefix):]
                keys = self.get_keys(subpath, method, view, view.schema)
                insert_into(links, keys, link)

            else:

                action_map = getattr(view, 'action_map', None)
                method_name = action_map.get(method.lower())
                schema = schemas.get(method_name)

                link = schema.get_link(path, method, base_url=self.url)
                subpath = path[len(prefix):]
                keys = self.get_keys(subpath, method, view, schema)
                insert_into(links, keys, link)

        return links


    def get_keys(self, subpath, method, view, schema=None):

        if schema and hasattr(schema, 'endpoint_name'):

            return [schema.endpoint_name]

        else:

            if hasattr(view, 'action'):
                action = view.action
            else:

                if is_list_view(subpath, method, view):
                    action = 'list'
                else:
                    action = self.default_mapping[method.lower()]

            named_path_components = [
                component for component
                in subpath.strip('/').split('/')
                if '{' not in component
            ]

            if is_custom_action(action):

                if len(view.action_map) > 1:
                    action = self.default_mapping[method.lower()]
                    if action in self.coerce_method_names:
                        action = self.coerce_method_names[action]
                    return named_path_components + [action]
                else:
                    return named_path_components[:-1] + [action]

            if action in self.coerce_method_names:
                action = self.coerce_method_names[action]

            return named_path_components + [action]

I specifically modified two functions get_links and get_keys as that allow me to achieve what I wanted.

Further, for all the functions in viewsets that I was writing I dedicated an individual schema for it. I simply created a dictionary to keep mappings of function name to schema instance. For better approach I created a separate file to store schemas. For eg. if I had a viewset Clients I created a corresponding ClientsSchema class and within in defined staticmethods which returned schema instances.

Example,

In file where I am defining my schemas,

class ClientsSchema():

    @staticmethod
    def list_schema():

        schema = schemas.ManualSchema(
            fields=[],
            description=''
        )

        schema.endpoint_name = 'Clients Listing'

        return schema

In my apis.py,

class Clients(viewsets.ViewSet):

    schemas = {
        'list': ClientsSchema.list_schema()
    }

    def list(self, request, **kwargs):
        pass

This setup allows me to define schemas for any type of functions that I add to my viewsets. In addition to it, I also wanted that the endpoints have an identifiable name and not the one generated by DRF which is like a > b > update > update. In order to achieve that, I added endpoint_name property to schema object that is returned. That part is handled in get_keys function that is overridden.

Finally in the urls.py where we include urls for documentation we need to use our custom schema generator. Something like this,

urlpatterns.append(url(r'^livedocs/', include_docs_urls(title='My Services', generator_class=CoreAPISchemaGenerator)))

For security purposes I cannot share any snapshots. Apologies for that. Hope this helps.

Answer 2

I think what you are trying to do is not possible. The ViewSet does not provide any method handlers, hence, you cannot use the @action decorator on the methods create and list, as they are existing routes.