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metadata

The REST framework includes a configurable mechanism for determining how the API responds to OPTIONS requests. This allows you to return API Schema or other resource information.

There is no widely adopted convention for what style of response HTTP OPTIONS requests should return, so we provide a specialized style to return some useful information.

Here is a sample response that demonstrates the information returned by default.

HTTP 200 OK
Allow: GET, POST, HEAD, OPTIONS
Content-Type: application/json

{
    "name": "To Do List"."description": "List existing 'To Do' items, or create a new item."."renders": [
        "application/json"."text/html"]."parses": [
        "application/json"."application/x-www-form-urlencoded"."multipart/form-data"]."actions": {
        "POST": {
            "note": {
                "type": "string"."required": false,
                "read_only": false,
                "label": "title"."max_length": 100}}}}Copy the code

Set the metadata scheme

You can use the ‘DEFAULT_METADATA_CLASS’ Settings key to set the global metadata class:

REST_FRAMEWORK = {
    'DEFAULT_METADATA_CLASS': 'rest_framework.metadata.SimpleMetadata'
}
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Or you can set a separate view metadata class:

class APIRoot(APIView):
    metadata_class = APIRootMetadata

    def get(self, request, format=None):
        return Response({
            ...
        })
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The REST Framework package contains only one metadata class implementation named SimpleMetadata. If you want to use a different style, you need to implement a custom metadata class.

Creating a Schema endpoint

If you have specific requirements for creating schema endpoints accessed through regular GET requests, consider reusing the metadata API for this purpose.

For example, you can use the following additional routes on a view set to provide a linkable Schema endpoint.

@list_route(methods=['GET'])
def schema(self, request):
    meta = self.metadata_class()
    data = meta.determine_metadata(request, self)
    return Response(data)
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There are several reasons to choose this approach, including that OPTIONS responses cannot be cached.

Custom metadata classes

If you want to provide a custom metadata class, you should extend BaseMetadata and implement determine_metadata(self, Request, View).

Some of the things you might want to do include returning schema information, using formats such as JSON Schema, or returning debugging information to the administrator user.

Take a chestnut

The following classes can be used to qualify the information returned to the OPTIONS request.

class MinimalMetadata(BaseMetadata):
    """ Don't include field and other information for `OPTIONS` requests. Just return the name and description. """
    def determine_metadata(self, request, view):
        return {
            'name': view.get_view_name(),
            'description': view.get_view_description()
        }
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Then configure your Settings to use this custom class:

REST_FRAMEWORK = {
    'DEFAULT_METADATA_CLASS': 'myproject.apps.core.MinimalMetadata'
}
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