django - Create Custom Error Messages with Model Forms

Question

I can see how to add an error message to a field when using forms, but what about model form?

This is my test model:

class Author(models.Model):
    first_name = models.CharField(max_length=125)
    last_name = models.CharField(max_length=125)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

My model form:

class AuthorForm(forms.ModelForm):
    class Meta:
        model = Author

The error message on the fields: first_name and last_name is:

This field is required

How do I change that in a model form?

Answer 1

New in Django 1.6:

ModelForm accepts several new Meta options.

• Fields included in the localized_fields list will be localized (by setting localize on the form field).
• The labels, help_texts and error_messages options may be used to customize the default fields, see Overriding the default fields for details.

From that:

class AuthorForm(ModelForm):
    class Meta:
        model = Author
        fields = ('name', 'title', 'birth_date')
        labels = {
            'name': _('Writer'),
        }
        help_texts = {
            'name': _('Some useful help text.'),
        }
        error_messages = {
            'name': {
                'max_length': _("This writer's name is too long."),
            },
        }

Related: Django's ModelForm - where is the list of Meta options?