Django multi field form validation

https://github.com/aumo/django_multifield_clean

Provides a Django form mixin that allows declaring validation methods (similar to the Django Form.clean_<field_name>() methods) working on multiple fields, allowing less boilerplate code in Form.clean().

Tested on Django 1.7, 1.8 and Python 2.7, 3.2, 3.3, 3.4

Installation

pip install django_multifield_clean

Usage

Make your form inherit from the multifieldclean.forms.MultiFieldCleanFormMixin mixin. Note that the mixin must come before the Django form class.

Declare methods starting with MULTIFIELD_CLEAN_METHOD_PREFIX (default is multi_clean) which arguments are named after field names.

Those methods will be called during the form validation process, after Form.clean(), with the field values their arguments are named after as parameters.

If an argument has no default value, the validation method is called only if the field it is refering to has a value.

Example:

from django import forms
from django.core.exceptions import Validationerror

from multifieldclean.forms import MultiFieldCleanFormMixin
    
    
# The mixin must be placed before 'forms.Form'
# so it can override its methods.
class HolidaysForm(MultiFieldCleanFormMixin, forms.Form):
    start = forms.IntegerField()
    end = forms.IntegerField()
        
    # Any method starting with "multiclean" will be
    # interpreted as a multi field validation method.
    # The method will only be called only if 'start' and
    # 'end' have values.
    def multiclean_holidays_end_after_they_start(self, start, end):
       if start > end:
           self.add_error('end', 
                          ValidationError('These holidays end before they even start!'))

Configuration

• MULTIFIELD_CLEAN_METHOD_PREFIX: modify the prefix used to detect validation methods, default is multiclean.

Why?

I often found myself writing a lot of boilerplate code when overriding the Form.clean() method, for example:

def clean(self):
    start = self.cleaned_data.get('start')
    end = self.cleaned_data.get('end')
    if start and end:
        if start > end:
            # etc...

It is boring to write and harder to read. This package tries to provide a solution to this issue.

Contributing

Pull requests are welcome.

Runnig the tests:

• To run the full suite, use tox.
• To run them for your current environment:
  • Install test requirements pip install -r test-requirements.txt
  • Install the targeted Django version.
  • Run py.test
  • Use py.test --cov multifieldclean to get the coverage report.