Question

I have a tree of models defined in my Django app (e.g. ‘a’ is a top level model, which has many ‘b’s, which has many ‘c’s). I also have the Views/Templates that render these appropriately. For each one of these models I typically need to do a Database query based on the current logged in user.

For example, it’s similar to how each user on stack overflow can mark a question with a star. If my model is the question, I would ask the model if the current user has this question starred and then render it appropriate in the template.

My first thought was to try to pass a parameter in the template (which I now know doesnt’ work).

# template
{{ question.is_starred(request.user) }}    # Can't work.

My second thought was to have some type of global variable (which I don’t like on principle).

# model
class question (Models.model)
    def _is_starred(self):
        # Use a global variable to find out the current logged in user!

My third thought was to have the View tell the model the currently logged in user, but the trouble is, I have a tree of model objects and I think I’d have to load and set every model in the tree, even if I don’t end up using them all. I assume that the objects are lazily loaded.

# view
def view_one_question(request, question_id):
    q = Question.objects.get(pk=question_id)
    q.SetCurrentlyLoggedInUser (request.user.id)
    # !!!! But what about the other network of objects that the question has?
    return render_to_response(...)

Any advice is appreciated. I’m new to Django and trying to start this project off with the best design possible.

Answer 1

Your first example is the right idea, but the wrong implementation. You can’t pass parameters to methods in Django templates. The easiest way around this is a simple filter:

# yourapp/templatetags/somefile.py

from django import template

register = template.Library()

@register.filter
def is_starred_for_user(question, user):
    return question.is_starred(user)

Then, in your template:

{% load somefile %}

{{ question|is_starred_for_user:request.user }}