The following table shows the method of our previously created classes that we want to be executed for each combination of HTTP verb and scope:

We must make the necessary resource routing configurations to call the appropriate methods and pass them all the necessary arguments by defining URL rules. The following lines configure the resource routing for the service. Open the previously created views.py file within the service folder and add the following code after the last line. The code file for the sample is included in the restful_python_2_02_01 folder, in the Flask01/service/views.py file:

service.add_resource(NotificationCategoryListResource,  
    '/notification_categories/') 
service.add_resource(NotificationCategoryResource,  
    '/notification_categories/<int:id>') 
service.add_resource(NotificationListResource,  
    '/notifications/') 
service.add_resource(NotificationResource,  
    '/notifications/<int:id>')

Each call to the service.add_resource method routes a URL to a resource; specifically, to one of the previously declared subclasses of the flask_restful.Resource superclass. Whenever there is a request to the API, and the URL matches one of the URLs specified in the service.add_resource method, Flask will call the method that matches the HTTP verb in the request for the specified class.