Question

I have a model:

class MyModel(models.Model):
    field_1 = models.ForeignKey(FirstModel)
    field_2 = models.ForeignKey(SecondModel)

And I want to display a form which both fields but only one field at the same time can be set, otherwise validation return error.

How to do it (preferably in the model)?

Answer 1

class MyModel(models.Model):
    field_1 = models.ForeignKey(FirstModel)
    field_2 = models.ForeignKey(SecondModel)

    def clean(self):
      num = filter(lambda e:e,[self.field_1, self.field_2])
      if len(num) != 1:
         raise ValidationError("only one attribute should be set")