'apply' in marshall_with is set for all decorators

[kam193]

Let's assume we declare a resource (for any reason) like this:

class HelloWorld(MethodResource):
    @marshal_with(TheTestSchema)
    @marshal_with(TheSecondSchema, code=300, apply=False)
    def get(self):
        return {'hello': 'world'}

I expected that TheTestSchema will be used in default case, and TheSecondSchema is present only in docs - and it looks in docs like this. But in fact, no one schema is used, in any case. I think apply=False is propagated to all marshal_with decorators for given method.

[kam193]

I found that this is how Annotation.merge works:

def merge(self, other):
        if self.inherit is False:
            return self
        return self.__class__(
            self.options + other.options,
            inherit=other.inherit,
            apply=self.apply if self.apply is not None else other.apply,
        )

As I see, it's used to merge mutliple decorators as well as inherited values. Furthermore, if I set inherit=False in the first decorator, second will be ignored (in docs and results).

[Querela]

I have the same issue and was puzzled for a very long time because my other methods worked, except for PUT. My main issue is that for responses without content and therefore no schema I can't use apply because then the None in the @marshal_with(None, ...) decorator will be converted into a dict later on (default value for empty schema) and the schema dumping will raise an error because the dict is no schema ...

---

The only solution I can think of is just using the schema myself to dump the object.

Another way (just to handle None-Schema or empty results) would be an additional check in wrapper.py:L58 (?) marshal_result(self, result, status_code). Here a further check before dumped = schema.dump(result) whether the schema object has a dump(..) method might be enough. That's unfortunately only a dirty fix (possibly?) but I'm not sure what other None-schemas can be supplied to the @marshal_with decorator that will require apply=False and where the functions return non-easily serializable objects. (like no JSON, string, numbers etc.) No real solution for different schemas with different apply states.

---

My use case below but only the PUT method fails. (Either because apply=True for None-Schema or apply=False for my TaskSchema where the Task-Resource is not serialized.)

@doc(tags=["api"])
class TaskResourceById(MethodResource):
    endpoint = "task"

    @doc(description="A task.")
    @marshal_with(TaskSchema, description="Get task with id.")
    def get(self, task_id):
        return self._get_task(task_id)

    @use_kwargs(TaskSchema)
    @marshal_with(TaskSchema, description="Update task.", apply=True)
    @marshal_with(None, code=404, description="No task found.", apply=False)
    def put(self, task_id, **kwargs):
        task = self._get_task(task_id)
        if not task:
            return None, 404
        for key, value in kwargs.items():
            setattr(task, key, value)

        local_object = db.session.merge(task)
        db.session.add(local_object)
        db.session.commit()

        return (
            local_object,
            200,
            {
                "location": url_for(
                    f"{bp_api.name}.{TaskResourceById.endpoint}",
                    task_id=local_object.id,
                )
            },
        )

    @marshal_with(None, code=204, description="Task deleted.", apply=False)
    @marshal_with(None, code=404, description="No task found.", apply=False)
    def delete(self, task_id):
        task = self._get_task(task_id)
        if not task:
            return None, 404

        local_object = db.session.merge(task)
        db.session.delete(local_object)
        db.session.commit()
        return None, 204

    # --------------------------------

    def _get_task(self, task_id):
        return Task.query.get(task_id)

    # --------------------------------

The error messages for PUT depending on apply:

...
  File "***/venv/lib/python3.7/site-packages/flask_apispec/wrapper.py", line 37, in __call__
    mv = self.marshal_result(rv, status_code)
  File "***/venv/lib/python3.7/site-packages/flask_apispec/wrapper.py", line 67, in marshal_result
    dumped = schema.dump(result)
AttributeError: 'dict' object has no attribute 'dump'

...
  File "***/venv/lib/python3.7/site-packages/flask/json/__init__.py", line 100, in default
    return _json.JSONEncoder.default(self, o)
  File "/usr/lib/python3.7/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Task is not JSON serializable