Get the request uri outside of a RequestHandler in Google App En

ghz 昨天 ⋅ 5 views

Get the request uri outside of a RequestHandler in Google App Engine (Python)

So, within a webapp.RequestHandler subclass I would use self.request.uri to get the request URI. But, I can't access this outside of a RequestHandler and so no go. Any ideas?

I'm running Python and I'm new at it as well as GAE.

Answer

In Google App Engine (GAE) with Python, if you're trying to access the request URI outside of a RequestHandler subclass, you won't have direct access to the self.request.uri property because that's specific to a request handled by the RequestHandler.

However, you can still retrieve the request URI outside of the RequestHandler by using the webapp framework's Request object. The request URI is generally available when processing the request in a request handler, but if you need access to it outside of a request handler, you'll typically need to ensure you have access to the request object itself.

1. Accessing Request URI within a RequestHandler (Standard Way)

Inside a RequestHandler subclass, you can directly access the URI as follows:

from google.appengine.ext import webapp
from google.appengine.ext.webapp import util

class MyHandler(webapp.RequestHandler):
    def get(self):
        # Accessing the request URI
        uri = self.request.uri
        self.response.out.write(f'URL: {uri}')
        
def main():
    application = webapp.WSGIApplication([('/', MyHandler)], debug=True)
    util.run_wsgi_app(application)

if __name__ == "__main__":
    main()

In this example, self.request.uri will return the complete URL requested by the client.

2. Accessing Request URI Outside RequestHandler

If you need to access the request URI outside of a RequestHandler, it’s a bit more involved since you're not within the request context where self.request is available. Typically, this happens in non-HTTP processing code, such as background tasks or other business logic.

To achieve this, you must have the request context passed into the logic you are working with, or make use of the GAE environment to inspect things. If you're not within a request context (i.e., you're not handling an incoming HTTP request), you can't directly access the URI.

Here’s how you can approach it:

Option 1: Passing the URI Explicitly

When you pass data between handlers or functions, you can pass the self.request.uri explicitly as a parameter.

For example:

class MyHandler(webapp.RequestHandler):
    def get(self):
        uri = self.request.uri
        self.process_request(uri)

    def process_request(self, uri):
        # Now you have access to the URI outside the handler
        # This could be passed to another part of your app logic
        self.response.out.write(f'Processed URI: {uri}')

In this case, you're explicitly passing the URI to another function (process_request) where you might use it in non-handler code.

Option 2: Using webapp2 (with Request Object)

If you're using webapp2 instead of webapp (which is recommended for modern GAE apps), the request object can be used in a more structured way. Here’s an example with webapp2:

import webapp2

class MyHandler(webapp2.RequestHandler):
    def get(self):
        uri = self.request.uri
        self.process_request(uri)

    def process_request(self, uri):
        # Use the URI outside the handler
        self.response.out.write(f'Processed URI: {uri}')

app = webapp2.WSGIApplication([('/', MyHandler)], debug=True)

Here, you are using webapp2's self.request.uri just like in the webapp example, and passing the URI explicitly into another method.

Option 3: Accessing the Request URI in Background Tasks

If you need to access the request URI in a background task, you can pass the URI to a task queue handler (or as a parameter) and access it there.

Example with background tasks:

from google.appengine.ext import webapp
from google.appengine.ext.webapp import util
from google.appengine.api import taskqueue

class MyHandler(webapp.RequestHandler):
    def get(self):
        uri = self.request.uri
        # Pass URI to background task
        taskqueue.add(url='/background-task', params={'uri': uri})

class BackgroundTaskHandler(webapp.RequestHandler):
    def post(self):
        uri = self.request.get('uri')
        # Process the URI in the background task
        self.response.out.write(f'Processed URI in background: {uri}')

def main():
    application = webapp.WSGIApplication([('/', MyHandler),
                                          ('/background-task', BackgroundTaskHandler)],
                                         debug=True)
    util.run_wsgi_app(application)

if __name__ == "__main__":
    main()

In this case, the URI is passed to the background task via the task queue, and the BackgroundTaskHandler retrieves it with self.request.get('uri').

Summary

  • Within a RequestHandler: You can access the URI with self.request.uri.
  • Outside of RequestHandler: Pass the URI explicitly to other functions, or use task queues if you're processing things asynchronously.
  • If you're using webapp2, you can follow a similar approach to webapp.

If you're working outside of the web request lifecycle (such as in background tasks or asynchronous logic), you will need to pass the URI explicitly as part of the data that needs to be processed. There's no global way to access the URI in these situations since the URI is part of the HTTP request context, which only exists during request handling.

#py