View cache busting logic fails if more than one GQL operation is provided in payload

[ethagnawl]

Per the GQL spec, more than one operation may be contained in the body of a request as long as a specific operation is specified using operationName. ExtraGraphQLView#get_operation_ast returns None in this case and results in the cache not being busted when a mutation does occur.

Here is the test I used to reproduce this:

# ...
            cache.set(cache_key, "no-not-me!", timeout=Config.DJANGO_CACHE_TTL)

            cache_was_set = cache.get(cache_key)
            assert cache_was_set

            api_query = f"""
query someName {{
  foo(id:"{lib_relay_id}") {{
    id
    bar(id:"{asset_relay_id}") {{
      edges {{
        node {{
          id
        }}
      }}
    }}
  }}
}}

mutation someOtherName {{
    createThing(title: "hello") {{
        status
        qux {{
            id
            title
            description
        }}
    }}
}}
        """
            private_client.post(
                "/api/v1/graphql/",
                data={
                    "query": api_query,
                    "operationName": "someOtherName",
                },
                content_type="application/json",
            )

            cache_was_cleared = not (bool(cache.get(cache_key)))
            assert cache_was_cleared

And I introduced this new method to get a list of all operations included in the payload and bust the cache if any contained a mutation. Having just written this out, I realize this approach is greedy and the specified operationName should be used to determine whether or not that operation is a mutation. But the following does address the broken behavior, if in a heavy handed way.

    def get_operations(self, request):
        """
        Return list of all operations -- regardless of type -- found in query
        """

        data = self.parse_body(request)
        query = request.GET.get("query") or data.get("query")

        if not query:
            return []

        source = Source(query, name="GraphQL request")
        document_ast = parse(source)

        operations = [
            definition
            for definition in document_ast.definitions
            if hasattr(definition, "operation")
        ]

        for operation in operations:
            logger.debug(f"operation: {str(operation)} - {operation.operation}")

        return operations

# ...

    def dispatch(self, request, *args, **kwargs):
        operations = self.get_operations(request)
        if operations and any(op.operation == OperationType.MUTATION for op in operations):