Django model's clean method multiple error

Question

I have been playing around with my test project

I have this clean method in my model

class SomeModel(models.Model):
    f1 = models.IntegerField()
    f2 = models.IntegerField()

    def clean(self):
        if self.f1 > self.f2:
            raise ValidationError({'f1': ['Should be greater than f1',]})
        if self.f2 == 100:
            raise ValidationError({'f2': ['That's too much',]})

I don't really know how to raise both errors and show it in the admin page because even if the two if is True, only the first if error is shown(obviously) how do I show both errors?

user2390182 · Accepted Answer · 2016-03-12 22:18:41Z

9

You could build a dict of errors and raise a ValidationError when you are done (if necessary):

class SomeModel(models.Model):
    f1 = models.IntegerField()
    f2 = models.IntegerField()

    def clean(self):
        error_dict = {}
        if self.f1 > self.f2:
             error_dict['f1'] = ValidationError("Should be greater than f1")  # this should probably belong to f2 as well
        if self.f2 == 100:
             error_dict['f2'] = ValidationError("That's too much")
        if error_dict:
             raise ValidationError(error_dict)

edited Mar 12, 2016 at 22:18

answered Mar 12, 2016 at 22:06

user2390182

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3 Comments

Sayse Over a year ago

Link to the docs that recommends this, "If you detect errors in multiple fields during Model.clean(), you can also pass a dictionary mapping field names to errors" (Note that the dict values are validation errors)

Jokinen Over a year ago

Link to the above quote for the docs of newer version of Django (1.9 docs no longer available): docs.djangoproject.com/en/4.0/ref/models/instances/…

R. Steigmeier Over a year ago

The problem with this solution is that if you have to raise multiple errors on one field (say because a related field is erroneous), you will override your first error message.

R. Steigmeier · Accepted Answer · 2022-10-09 10:11:42Z

0

I would expand the accepted answer by setting a classmethod like this:

@classmethod
def add_error(cls, errordict, error):
    for key, value in error.items():
        if key in errordict:
            if isinstance(errordict[key], str) or isinstance(errordict[key], ValidationError):
                errordict.update({key: [errordict[key], value]})
            elif isinstance(errordict[key], list):
                errordict[key].append(value)
        else:
            errordict.update(error)
    return errordict

That way, if a key already exists in your error dict, it will be casted in a list. That way, all the errors will be raised, even if there are multiple errors per field.

adderror(error_dict, {'field', 'error message'})

edited Oct 9, 2022 at 10:11

answered Oct 9, 2022 at 9:35

R. Steigmeier

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