How to use Decorators with Flask-RESTPlus for each function call?

Question

I have problems to apply a decorator to my Resource. The Api decorators parameter gets applied to each Resource-function or how do I have to understand the decorators parameter? My decorator gets only applied at the start up and not on each function call. What am I doing wrong?

from flask import Flask, Blueprint
from flask.ext.restplus import Api, Resource, fields

app = Flask(__name__)

def my_decorator(input):
    print("my decorator")
    return input

api_blueprint = Blueprint('index', __name__, url_prefix='/0')

api = Api(api_blueprint, version='0.1.0', title='Index API',
    description='The Index API helps to find things faster in the own database',
    # ui=False,
    decorators=[my_decorator]
)

app.register_blueprint(api_blueprint)

ns = api.namespace('index', description='Index API')


search_id_score_model = api.model('id', {
    'id': fields.String(required=True),
    'score': fields.Float(required=True)
})

search_result_model = api.model('result', {
    'key': fields.String(required=True),
    'ids': fields.List(fields.Nested(search_id_score_model, required=True), required=True)
})


@ns.route('/search/<string:query>')
class Search(Resource):
    '''Serach'''

    @api.marshal_list_with(search_result_model)
    @my_decorator
    def get(self, query):
        '''fetch result by query'''
        return None

if __name__ == '__main__':
    app.run(debug=True)

Answer 1

There is two decorators levels: API-wide and Resource-wide.

The Api.decorators parameter allow to apply decorators to all resources whereas the Resource.method_decorators will be applied on all method for a given resource.

The problem in your case it that your decorator only call the print once applied and not once called. You should modify your decorator like this:

def my_decorator(func):
    def wrapper(*args, **kwargs):
        print("my decorator")
        return func(*args, **kwargs)
    wrapper.__doc__ = func.__doc__
    wrapper.__name__ = func.__name__
    return wrapper

Notice the __doc__ and __name__ affectations. The first allow to correctly extract the description, the __name__ allow to avoid automatic naming collisions. The name is optional if you manually specify an endpoint for each resource.