Question

I have browsed through lots of "through table access" in SO so if I missed something, feel free to close this.

I have a table A, a table B, in an n-n relationship and a through table C. C contains the "in_stock"property. Obviously, a pairing of object A1 and B1 will always be unique. So if I am given A1, and B1, how do I access in a template, the "in_stock" property in the "through table" C?

Additional INfo:

I am looping over the Bs A1 has in the template, so in an iteration I can have A1-B1, on another A1-B2, etc.

Answer 1

I use a custom tag to do so :

(assuming you have A1 in the template)

{% load custom_tag %}
<ul>
{% for b in Bs %}
    {% autoescape off %}
        <li>in_stock for {{ A1 }} and {{ b }} : {{ A1|through:b }}</li>
    {% endautoescape %}
</ul>
{% endfor %}

custom_tag.py

register = template.Library()


def through(A1, b):
    t = "%s" % (C.objects.get(b=b, a=A1).in_stock)
    return t


register.filter(through)