documentation talks about validators but separates definition and usage

[nicolas@…]

The top of the page deine a validator, the answer, but not the section about the validators.

This is at the top:

""" Validators are simple functions (or callables) that take a single argument and raise ValidationError on invalid input. Validators are run after the field’s to_python and validate methods have been called. """

This is the section about validators (middle of the page):

"""
Using validators

Django’s form (and model) fields support use of simple utility functions and classes known as validators. These can be passed to a field’s constructor, via the field’s validators argument, or defined on the Field class itself with the default_validators attribute.

Simple validators can be used to validate values inside the field, let’s have a look at Django’s SlugField:

from django.forms import CharField
from django.core import validators

class SlugField(CharField):

default_validators = [validators.validate_slug]

As you can see, SlugField is just a CharField with a customized validator that validates that submitted text obeys to some character rules. This can also be done on field definition so:

slug = forms.SlugField()

is equivalent to:

slug = forms.CharField(validators=[validators.validate_slug])

"""

I think a simple example of a validator would be a nice thing to add. Or at least provide a link to the source code of the validator showcased.

This is from the 1.6 and (at the time), dev version too:

​https://docs.djangoproject.com/en/1.6/ref/forms/validation/
​https://docs.djangoproject.com/en/dev/ref/forms/validation/

[Tim Graham]

Yes, I think at least linking to the ​validators reference guide would be helpful. If you could submit a patch I'll be happy to review and commit it.

[benhuckvale]

I made some changes along the lines suggested, including the link to the validators reference guide.
Pull request is ​https://github.com/django/django/pull/1663.

[Tim Graham <timograham@…>]

In 98e0453f00958af63b50e70990903eb6a04e1933:

Fixed #21120 -- Added more explicit text on using validators and link to writing validators.

Thanks nicolas at niconomicon.net for the suggestion.

[Tim Graham <timograham@…>]

In cdb56725d4424cc58147e2ffd4426511aa95775e:

[1.6.x] Fixed #21120 -- Added more explicit text on using validators and link to writing validators.

Thanks nicolas at niconomicon.net for the suggestion.

Backport of 98e0453f00 from master

[Tim Graham <timograham@…>]

In a722dfda93eafd6ff02b91f7a222eaccfc444ef4:

[1.5.x] Fixed #21120 -- Added more explicit text on using validators and link to writing validators.

Thanks nicolas at niconomicon.net for the suggestion.

Backport of 98e0453f00 from master