ValidationError is not picklable

[Alex Hayes]

I have a use case where I'd like to pickle ValidationError however it throws up as error:

For example, I'd expect the following to work:

import pickle
from django.core.exceptions import ValidationError
pickle.loads(pickle.dumps(ValidationError('eggs', 'sausage')))

Results in:

TypeError: __init__() takes at least 2 arguments (1 given)

The reason for this is because ValidationError does not call super.

[loic84]

It's a good idea as PY2 can't pickle naive exceptions see: ​http://bugs.python.org/issue1692335 (fix was backported all the way to python 3.2).

Since we'd now be calling the constructor, I think it's good practice to pass all arguments so the args attribute holds meaningful information.

I've completed the test suite to ensure the more complex scenarios like nested ValidationError, or Validation with error_dict behave as expected.

PR ​https://github.com/django/django/pull/2022.

[Loic Bistuer <loic.bistuer@…>]

In a8f4553aaecc7bc6775e0fd54f8c615c792b3d97:

Fixed #21555 -- Made ValidationError pickable.

Thanks trac username zanuxzan for the report and original patch.