Question

In Python, if you have a Django form form with a field named foo, you can’t use the attribute access syntax form.foo to access the field; instead you must use form.fields['foo'].

But in a template you can — and normally do — use {{ form.foo }} to render the field, using the normal attribute access syntax that works for any object in templates.

Why/how does the template {{ form.foo }} work when Python form.foo doesn’t? Is it a bit of special handing that Django does when rendering templates? Or am I just misunderstanding something simple?

EDIT: I know that Django’s template language isn’t Python and there are many differences from Python. I am just curious why the {{ form.foo }} syntax works and/or how it’s implemented in the case of forms. After all, normally the template {{ object.attribute }} syntax DOES work analogously to the Python object.attribute syntax, but in the case of a form it seems to be handled as a special case.

Answer 1

Django’s templating language, as Kerrek SB mentions, isn’t Python, even if it sometimes looks like it. {{ object.attribute }} does appear to mimic Python’s attribute lookup, but it is just a special case of {{ a.b }} in the template language.

When you use {{ a.b }} in a template, the interpreter will first look up a in the current context. Once it has that, it will try the following things to resolve a.b:

• a["b"]
• a.b
• a.b() (in the case where b is a method of a)
• a[b] (in the case where b is a number)

For forms, specifically, a["b"] is what is used. You can refer to a field "foo" as form.fields["foo"] or as form["foo"]. That bit of magic comes from the form class, though, and not the template language.