diff options
Diffstat (limited to 'docs/ref')
| -rw-r--r-- | docs/ref/forms/validation.txt | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/docs/ref/forms/validation.txt b/docs/ref/forms/validation.txt index 0831a54c74..8353b3d5b4 100644 --- a/docs/ref/forms/validation.txt +++ b/docs/ref/forms/validation.txt @@ -268,9 +268,12 @@ 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. +classes known as validators. A validator is merely a callable object or +function that takes a value and simply returns nothing if the value is valid or +raises a :exc:`~django.core.exceptions.ValidationError` if not. These can be +passed to a field's constructor, via the field's ``validators`` argument, or +defined on the :class:`~django.forms.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``:: @@ -291,6 +294,13 @@ is equivalent to:: slug = forms.CharField(validators=[validators.validate_slug]) +Common cases such as validating against an email or a regular expression can be +handled using existing validator classes available in Django. For example, +``validators.validate_slug`` is an instance of +a :class:`~django.core.validators.RegexValidator` constructed with the first +argument being the pattern: ``^[-a-zA-Z0-9_]+$``. See the section on +:doc:`writing validators </ref/validators>` to see a list of what is already +available and for an example of how to write a validator. Form field default cleaning ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |