Django TextField max_length validation for ModelForm

Question

Django does not respect the max_length attribute of TextField model field while validating a ModelForm.

So I define a LimitedTextField inherited from the models.TextField and added validation bits similar to models.CharField:

from django.core import validators class LimitedTextField(models.TextField): def __init__(self, *args, **kwargs): super(LimitedTextField, self).__init__(*args, **kwargs) self.max_length = kwargs.get('max_length') if self.max_length: self.validators.append(validators.MaxLengthValidator(self.max_length)) def formfield(self, **kwargs): defaults = {'max_length': self.max_length} defaults.update(kwargs) return super(LimitedTextField, self).formfield(**defaults)

But this still has no affect on ModelForm validation.

What am I missing?

chhantyal · Accepted Answer · 2016-09-27 15:16:55Z

As of Django 1.2 this can be done by validators at model level, as explained here: https://docs.djangoproject.com/en/stable/ref/validators/

from django.core.validators import MaxLengthValidator class Comment(models.Model): comment = models.TextField(validators=[MaxLengthValidator(200)])

Since Django 1.7, you can use max_length which is only enforced in client side. See here

From django 1.7, yon can use max_length attribute in TextField

Michael Godshall · Accepted Answer · 2010-07-09 03:10:45Z

12

You can enforce a max length for a TextField by defining a CharField with a Textarea widget like this:

class MyClass(models.Model): textfield = models.TextField() class MyForm(forms.ModelForm): textfield = forms.CharField( max_length = 50, widget = forms.Textarea ) class Meta: model = MyClass fields = ('textfield',)

answered Jul 9, 2010 at 3:10

Michael Godshall

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2 Comments

onurmatik Over a year ago

but then i should repeat this for every text field that i want to limit. it would be much better if nothing other then specifying max_length is required.

Michael Godshall Over a year ago

Yes, specifying max_length in the model would be a little easier, but the solution I offered is the standard approach you will find in many django apps, and even within django itself (see django.contrib.comments). I have yet to see the custom TextField you are describing. Good luck.

Wariored · Accepted Answer · 2018-06-08 11:12:36Z

0

No need to import MaxLengthValidator from validators for Django 2.x

from django.db import models class Comment(models.Model): comment = models.TextField(max_length=200)

edited Jun 8, 2018 at 11:12

answered Jun 8, 2018 at 10:35

Wariored

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2 Comments

DaFois Over a year ago

It's always better to add some explanation to the answer. ;)

Daviddd Over a year ago

From the doc: If you specify a max_length attribute, it will be reflected in the Textarea widget of the auto-generated form field. However it is NOT ENFORCED at the model or database level.

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