When coding Django one of my most important goals is avoiding all kind of hardcoded urls in my applications. Let's see this line from one of my app's URLConf:

url(r'^edit/object/(?P\w+)/$', 'object_edit', name='object_edit'),

This points to a page like /edit/object/123, notice I'm using a named pattern here, and calls a view defined with:

def object_edit(request, object_id):

Then I can do what I need with the object identified by object_id.

Now, imagine I have a list of objects in a template so I can add an edit link to each one of them, something like this:

<a href="{% url object_edit object_id=4}">edit object</a>

Notice that 4? I put it there just for making my point clear, what I really want to do is something like:

<a href="{% url object_edit object_id={{ object.object_id }} %}">edit object</a>

but that produces an error like this: TemplateSyntaxError at ... Could not parse the remainder: '{{' from '{{'.

It seems a template variable can't be used inside a {% url %} tag, and I guess the same applies to any template tag. After thinking a bit about how other tags work with variables, the {% for %} loop for example, I decided to get rid of the {{ and }}:

<a href="{% url object_edit object_id=object.object_id %}">edit object</a>

And yep, that worked. I hope this helps anybody else having a similar question.