id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
19591	QuerySet silently allows querying with objects of wrong class	Chris Wilson	nobody	"After a recent refactor, I thought our code was working correctly because the tests passed. Then I discovered that QuerySet allows you to pass objects of the wrong type in queries:

For example, this does not fail, and even returns some results:

{{{
Price.objects.filter(product=user.account_type)[0].pk
}}}

Even though `Price.product` is actually (now) a ForeignKey to `Product`, not `AccountType`. The correct code would be this:

{{{
Price.objects.filter(product__account_type=user.account_type)[0].pk
}}}

I think that QuerySet just extracts the object's PK without checking that it's an instance of the correct type.

I think it's not doing what is ""obvious"". I expect to get back `Price` objects whose `product` object is the same as the one I passed in, which is impossible if Price.product has a different class. Instead, it's silently rewritten my query into a less strict one, that only ensures that the FK is the same as the PK of the object I passed in, regardless of the type of that object.

Perhaps strictly it should return an empty set, because it's impossible for any Price objects to match the criteria that I provided, but I don't think that's very useful behaviour. Since this is a logic error in the application, I suggest throwing an exception to point it out instead.
"	Uncategorized	closed	Database layer (models, ORM)	1.5-alpha-1	Normal	duplicate			Unreviewed	0	0	0	0	0	0