How to use urllib2.urlopen to make POST request without data argument

Question

I am trying to use urllib2.urlopen to perform GET and POST requests via the Facebook Graph API. I noticed from here: https://stackoverflow.com/questions/2690723/facebook-graph-api-and-django that I can perform GET request fairly easily.

And from here: How to send a POST request using django? and the Python docs http://docs.python.org/library/urllib2.html it seems that it needs the data param to perform a POST request.

But looking at the Facebook's API: http://developers.facebook.com/docs/reference/api/event/#invited it says

You can invite users to an event by issuing an HTTP POST to /EVENT_ID/invited/USER_ID

I am not sure how I could do that with urlopen, since opening this url directly is going to only check if the user has been invited, as mentioned on the API page:

You can check whether a specific user has been invited to an event by issuing an HTTP GET to /EVENT_ID/invited/USER_ID:

Appreciate the input.

Answer 1

It sounds like you want to send an empty POST request, even though urllib2.urlopen() only sends a post when you specify the data parameter.

It seems like it actually sends an empty POST if you set data="", and GET request only when data=None:

urllib2.urlopen("http://127.0.0.1:8000", data="")
"POST / HTTP/1.1" 501 - 

urllib2.urlopen("http://127.0.0.1:8000", data=None)
"GET / HTTP/1.1" 200 -

Hope that helps. I got the response printouts from the little HTTP server they have an example for here: http://docs.python.org/library/simplehttpserver.html

Answer 2

Another way to send an empty POST is to create a Request and override its get_method. This is more work in this case, but may be cleaner in other cases (if you already have a Request, for example).

    request = urllib2.Request(url)
    request.get_method = lambda: 'POST'
    urllib2.urlopen(request)

get_method is a method that returns the method to be used, so here we override it with a lambda function that returns 'POST'.