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 create the main entry point for the application, initialize it with a Flask application, and configure the resource routing for the service. Open the previously created service/service.py
file and add the following lines. The code file for the sample is included in the restful_python_2_01_01
folder, in the Flask01/service/service.py
file:
app = Flask(__name__) service = Api(app) service.add_resource(NotificationList, '/service/notifications/') service.add_resource(Notification, '/service/notifications/<int:id>', endpoint='notification_endpoint') if __name__ == '__main__': app.run(debug=True)
The code creates an instance of the flask_restful.Api
class and saves it in the service
variable. 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. When there is a request to the service 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. The method follows standard Flask routing rules.
For example, the following line will make an HTTP GET
request to /service/notifications/
without any additional parameters to call the NotificationList.get
method:
service.add_resource(NotificationList, '/service/notifications/')
Flask will pass the URL variables to the called method as arguments. For example, the following line will make an HTTP GET
request to /service/notifications/26
to call the Notification.get
method, with 26
passed as the value for the id
argument:
service.add_resource(Notification, '/service/notifications/<int:id>', endpoint='notification_endpoint')
In addition, we can specify a string value for the endpoint argument to make it easy to reference the specified route in the fields.Url
fields. We pass the same endpoint name, 'notification_endpoint'
, as an argument in the uri
field declared as fields.Url
in the notification_fields
dictionary that we use to render each NotificationModel
instance. This way, fields.Url
will generate a URI that considers this route.
We just required a few lines of code to configure resource routing and endpoints. The last line just calls the app.run
method to start the Flask application, with the debug
argument set to True
to enable debugging. In this case, we start the application by calling the run
method to immediately launch a local server. We could also achieve the same goal by using the flask
command-line script. However, this option would require us to configure environment variables and the instructions are different for the platforms that we are covering in this book: macOS, Windows, and Linux.