CODEWITHSUNDEEP
djangodjango-modelsdjango-orm
darkhorse
darkhorse

Reputation: 8782

How to use a string to call a queryset in Django?

I have 2 models which have foreign keys referencing a third model. Its something like this:

class Foo(models.Model):
    ...

class Model1(models.Model):
    foo = models.ForeignKey(Foo, related_name='m1_related')

class Model2(models.Model):
    foo = models.ForeignKey(Foo, related_name='m2_related')

Now, lets say I have an instance of Foo and a string which is either 'm1' or 'm2'. How can I use this string to call the appropriate queryset using the related names?

Something like this:

my_str = 'm1'
foo.my_str+'_related'.objects.all()

Obviously, the above code is just wrong in so many ways, but hopefully that makes it clear. I don't want to use if else conditions for this, as the number of models will be a lot, and all their related names will follow the same pattern.

Thanks.

Upvotes: 0

Views: 39

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 477607

You can use getattr(..) to obtain the name of an attribute, like:

my_str = 'm1'
getattr(foo, my_str+'_related').objects.all()

A call to getattr(x, 'y') is equivalent to x.y (note that in getattr(..) the 'y' is a string. So we can use getattr(..) obtain the attribute.

Upvotes: 2

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