Django reverse routes - two optional parameters

Question

I have a question about Django and it's routing system. I believe that it can be powerfull, but right now I am struggling with one issue I don't experience when working in other frameworks and I can't seem to get a grip on it. Worth to mention that I don't have much experience with Django at this point.

The issue is simple - I have a view which takes two optional parameters, defined like this

def test_view(id=None, grid=None):

Both parameters are optional and frequently are not passed. Id can only be an integer and grid will never be an integer (it is a special string to control datagrid when I don't want to use sessions). I have a route defined like this:

url(a(r'^test_view   (\/(?P<id>\d+))?  (\/(?P<grid>[^\/]+))?   \/?$'), views.test_view, name='test_view'),

This works great and I am not having trouble with using one-way routes. But when I try to use the reverse function or url template tag, following error occurs:

Reverse for 'test_view' with arguments '('20~id~desc~1',)' and keyword arguments '{}' not found.

In this example I tried to find reverse without the id, just with the grid parameter. I have tried various methods of passing parameters to the reverse function:

(grid, )
(None, grid)
('', grid)
{id=None, grid=grid}

All of them result in same error or similliar one.

Is there a way to implement this in django? Maybe just disable the cool URL for the grid parameter. That is how I do it in for example Nette framework for PHP, isntead of having an url like this: 'localhost/test_view/1/20~id~desc~1' I have url like this: 'localhost/test_view/1?grid=20~id~desc~1'. This would be completely sufficient, but I have no idea how to achive this in Django.

Answer 1

As you note in your question, the best way to achieve this is to use standard GET query parameters, rather than doing it in the path itself. In Django you do that exclusively in the view; the URL itself is then just

url(r'^test_view$',  views.test_view, name='test_view'),

and you request it via localhost/test_view?id=1&grid=20~id~desc~1. You get the params from request.GET, which is a dictionary-like object; you can use .get so that it does not raise a KeyError when the key is not provided.

def test_view(request):
    id = request.GET.get('id')
    grid = request.GET.get('grid')