Django CharField limitations

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how can I specify a blacklist for a CharField. However I want the blacklist to be effective in the Django admin panel aswell...otherwise I would just validate it in the view.

By blacklist I mean values that can't be used. I also set unique for the value but I would like to disable a few strings aswell.

Thanks, Max

I would override the model's save() method and the to be inserted value against a blacklist before calling the parent class' save() method.

Something like that (simplified):

class BlackListModel(models.Model):   
   blacklist = ['a', 'b', 'c']

   # your model fields definitions...

   def save(self, *args, **kwargs):
        if self.blacklist_field in self.blacklist:
            raise Exception("Attempting to save a blacklisted value!")
        return super(BlackListModel, self).save(*args, **kwargs)

That way it works in all of your applications.

Django CharField limitations, I would override the model's save() method and the to be inserted value against a blacklist before calling the parent class' save() method. Django has various numeric fields available for use in models, e.g. DecimalField and PositiveIntegerField.Although the former can be restricted to the number of decimal places stored and the overall number of characters stored, is there any way to restrict it to storing only numbers within a certain range, e.g. 0.0-5.0 ?

This is not possible out of the box. You would have to write a custom form field or otherwise add custom admin handling to do admin-level validation. To do it at the database level, I suspect you would need to set up some kind of trigger and stored procedure, but that's not my area so I'll leave that to others.

Django CharField limitations, Django CharField limitations. django models django charfield max length django onetoonefield django manytomanyfield django foreign key related name Field options¶. Each field takes a certain set of field-specific arguments (documented in the model field reference).For example, CharField (and its subclasses) require a max_length argument which specifies the size of the VARCHAR database field used to store the data.

Since we're a few years later, you should write a custom blacklist validator:

from django.db import models    
from django.core.exceptions import ValidationError

def validate_blacklist(value):
    if value in ['a', 'b', 'c']:
        raise ValidationError(
            "'a', 'b' and 'c' are prohibited!",
            params={'value': value},

class MyModel(models.Model):
    even_field = models.CharField(max_length=200, validators=[validate_even])

See: Django Validators for full documentation.

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