RequestHandler classes ¶

Your application is defined in classes that extend tipfy.RequestHandler. The main logic for the app goes here: the handler decides which data will be fetched and how it will be displayed to the user. When you define the URLs that your app will handle, they map to RequestHandler classes. Handlers are very simple to implement; they are similar to webapp handlers. Let's take a look at how they work.

Methods¶

A RequestHandler class must implement methods that correspond to the HTTP methods that it will accept: if it will handle GET requests, it must have a get() method; if it will handle form submissions in POST requests, it must have a post() method; and so on. These methods always return a Response object with the output to be displayed to the client. For example:

from tipfy import RequestHandler, Response

class MyFirstHandler(RequestHandler):
    def get(self, **kwargs):
        return Response('I can handle a GET request.')

    def post(self, **kwargs):
        return Response('I can also handle a POST request.')

    def put(self, **kwargs):
        return Response('I can also handle a PUT request.')

This handler accepts GET, POST and PUT requests. The appropriate method is called when this handler is executed, and the application will display the returned response.

URL arguments¶

A RequestHandler class is instantiated right after a URL rule matches the current URL; then the method corresponding to the current HTTP method is called passing the keyword arguments from the matched URL rule. So let's say that we have the following URL rules:

urls.py

from tipfy import Rule

def get_rules(app):
    """Returns a list of URL rules for the application."""
    rules = [
        Rule('/<who>', endpoint='hello', handler='handlers.MyFirstHandler'),
    ]
    
    return rules

Here we define a URL rule with a variable "who" that will be passed to the RequestHandler as a keyword argument. We can now define a handler that uses that variable:

handlers.py

from tipfy import RequestHandler, Response

class MyFirstHandler(RequestHandler):
    def get(self, who=None):
        return Response('Hello, %s!' % who)

When you access http://localhost:8080/world, you'll see a message using the variable from the URL. Here we defined only one variable in the rule, but it could be more: the RequestHandler method will receive all variables from the rule as keyword arguments.

• Version: latest
• Edited by moraes on 7/3/10 3:46 PM
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