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pythondjangodjango-1.4

Django QuerySet: filter by the value of another field

I have a model I wish to filter by its attribute a. The model also has another attribute b. I am trying to filter entries where a is 0 or a has the value of the b attribute (for each row, obviously). How can I filter by the value of another column?

Here is what I have tried, and the missing piece:

MyModel.objects.filter(Q(a=0) | Q(a=???)) # ??? is to be the value of the `b` column

I am using Django 1.4 and I know it is an old version that is no longer supported but unfortunately performing the upgrade is not up to me.

Solution

  • I think you can use an F expression with your Q object:

    MyModel.objects.filter(Q(a=0) | Q(a=F('b')))

    I'll also suggest you schedule your upgrade now, otherwise, you'll be missing out on other features and security fixes.