Bounds and constraints in Django ForeignKey field values -- and how they can effect queryset results

For example if I have models.py like this:

Handler(models.Model):
    model1 = ForeignKey(Model1)
    model2 = ForeigKey(Model2)
    user = models.ForeignKey(User)

For example there are 100 instances of Handler with Model1 id = 1, but Model 2 id for this 100 instances is in range 1 to 5. And when I do something like this:

Handles.objects.filter(model1=1).values_list('model2_id', flat=True)

It returns list of 5 id values or list of 100 id values, which are be repeated? And if it return 100 values is there possibility to remain only one v开发者_如何学Pythonalue for every repeated value?

It will return a list of 100 id values. If you want to get the unique 5 ones, then you can do that in python.

model2_id_uniq_values = list(set(Handles.objects.filter(model1=1).values_list('model2_id', flat=True)))

It may not be the most finely tuned algorithm, and by using a set, you would lose the order. But for your purposes it appears to work.