Question

This seems to me like a very simple question, but I can’t seem to find the answer.

All I need to do is determine the number of objects returned by a database query.

The specific circumstance is this: I have a model named Student. This model has a ManyToManyField member named courses_current, which relates to a table of Course models. When I pass my Student instance to a template, I want to be able to do something like the following (the syntax may not be exact, but you’ll get the basic idea):

<div id="classes">
{% if student.classes_current.all.size == 0 %}
    <h1> HEY! YOU AREN'T TAKING ANY CLASSES! REGISTER NOW!
{% else %}
    Here are your courses:
    <!-- ... -->
{% endif %}
</div>

Now, I’m fairly certain that X_set.all.size is not a real thing. In the manage.py shell I can just use len(student.classes_current.all()), but I don’t know of any way to use built-in functions, and “dictionary-like objects” don’t have .size() functions, so I’m at a loss. I’m sure there’s a very simple solution (or at least I hope there is), but I can’t seem to find it.

Answer 1

{{ student.classes_current.all.count }} but be warned that it doesn’t fetch the objects so you will need to do a separate query if you want to loop over them.