Question

Something like this question:

Distinguish between null and missing parameters in ASP.NET MVC4

…except for WSGI. How can I distinguish between a “no value” query param, and a query param that is not present.

According to this documentation, this code:

value = self.request.get('n')

..returns the empty string when the query parameter is not present.
What will it return if the query param is present but has no value, eq a query string of ?n ?

I am trying to test this, but honestly, I’m having trouble with GAE.

Answer 1

As specified in that doc you linked:

get(argument_name, default_value=”)

Specify the default_value parameter:

self.request.get('n', None)

will return None if the parameter n isn’t present (e.g. ?foo=bar). If the parameter is present but doesn’t specify a value, you’ll get an empty string (e.g. ?n=&foo=bar).