Snippet

Custom Form Validation

Custom validation allows you to check specific field data against business rules before saving it.

snippet.py

python

from django import forms
from django.core.exceptions import ValidationError
 
class ContactForm(forms.Form):
    email = forms.EmailField()
 
    def clean_email(self):
        data = self.cleaned_data['email']
        if 'spam' in data:
            raise ValidationError('Invalid email address!')
        return data

django

Breakdown

def clean_email(self):

Django looks for methods starting with 'clean_' followed by the field name.

raise ValidationError(...)

This stops the form from being processed and shows an error to the user.

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Custom Form Validation

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