Is this the way to validate Django model fields?

by

Firstly, you shouldn’t override full_clean as you have done. From the django docs on full_clean:

Model.full_clean(exclude=None)
This method calls Model.clean_fields(), Model.clean(), and Model.validate_unique(), in that order and raises a ValidationError that has a message_dict attribute containing errors from all three stages.

So the full_clean method already calls clean, but by overriding it, you’ve prevented it calling the other two methods.

Secondly, calling full_clean in the save method is a trade off. Note that full_clean is already called when model forms are validated, e.g. in the Django admin. So if you call full_clean in the save method, then the method will run twice.

It’s not usually expected for the save method to raise a validation error, somebody might call save and not catch the resulting error. However, I like that you call full_clean rather than doing the check in the save method itself – this approach allows model forms to catch the problem first.

Finally, your clean method would work, but you can actually handle your example case in the model field itself. Define your CharField as 

name = models.CharField(max_length=128)

The blank option will default to False. If the field is blank, a ValidationError will be raised when you run full_clean. Putting default=None in your CharField doesn’t do any harm, but it is a bit confusing when you don’t actually allow None as a value.

More Related Contents:

  1. Django dynamic model fields
  2. Django set default form values
  3. How to create an object for a Django model with a many to many field?
  4. django abstract models versus regular inheritance
  5. Django post_save() signal implementation
  6. Getting TypeError: __init__() missing 1 required positional argument: ‘on_delete’ when trying to add parent table after child table with entries
  7. Get all related Django model objects
  8. difference between filter with multiple arguments and chain filter in django
  9. LEFT JOIN Django ORM
  10. Django Rest Framework and JSONField
  11. django.db.migrations.exceptions.InconsistentMigrationHistory
  12. Django Blob Model Field
  13. Django – How to rename a model field using South?
  14. Django Many-to-Many (m2m) Relation to same model
  15. How to have a Python script for a Django app that accesses models without using the manage.py shell?
  16. How to display uploaded images in “Change List” page in Django Admin?
  17. How to change the file name of an uploaded file in Django?
  18. How to monkey patch Django?
  19. Easiest way to rename a model using Django/South?
  20. models.py getting huge, what is the best way to break it up?
  21. matching query does not exist Error in Django
  22. Django admin file upload with current model id
  23. one-to-many inline select with django admin
  24. How can I set a default value for a field in a Django model?
  25. Django filter JSONField list of dicts
  26. how to manually assign imagefield in Django
  27. Django ModelForm to have a hidden input
  28. Add custom form fields that are not part of the model (Django)
  29. Can a dictionary be passed to django models on create?
  30. Django cannot import name x [duplicate]

Leave a Comment