mirror of https://github.com/django/django.git
146 lines
4.0 KiB
Plaintext
146 lines
4.0 KiB
Plaintext
.. _ref-validators:
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==========
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Validators
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==========
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.. versionadded:: 1.2
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Writing validators
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==================
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A validator is just a callable that takes a value, and raises a
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``ValidationError`` if it doesn't meet some criteria. They can be useful for
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re-using validation logic between different types of fields.
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For example, lets write a validator that only allows even numbers::
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from django.core.exceptions import ValidationError
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def validate_even(value):
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if value % 2 != 0:
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raise ValidationError(u'%s is not an even number' % value)
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You can then add this to your model fields via the field's ``validators``
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argument::
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from django.db import models
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class MyModel(models.Model):
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even_field = models.IntegerField(validators=[validate_even])
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Since values are converted to python before validators are run, you can even
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use the same validator with forms::
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from django import forms
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class MyForm(forms.Form):
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even_field = forms.IntegerField(validators=[validate_even])
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How validators are run
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======================
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See the :ref:`form validation <ref-forms-validation>` for more information on
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how validators are run in forms, and :ref:`Validating objects <validating-objects>`
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for how they are run in models.
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Built-in validators
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===================
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Django has a collection of callable validators for use with model and form
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fields. Many of them are used internally, but they are available for use with
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your own fields too. They can be used in addition to, or in lieu of custom
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field.clean() methods.
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``RegexValidator``
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------------------
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.. class:: RegexValidator(regex=None, message=None, code=None)
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.. attribute:: regex=None
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The regular expression to search for the provided ``value``. Raises a
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``ValidationError`` if no match was found.
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.. attribute:: code='invalid'
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The error code to use if validation fails. Defaults to ``'invalid'``.
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.. attribute:: message=None
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The error message to use if ``regex`` doesn't match the provided ``value``.
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``URLValidator``
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----------------
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.. class:: URLValidator(verify_exists=False, validator_user_agent=URL_VALIDATOR_USER_AGENT)
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A ``RegexValidaor`` that ensures a value looks like a URL, and optionally
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verifies that the URL actually exists. Raises an error code of ``'invalid'``
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if it doesn't look like a URL, and a code of ``'invalid_link'`` if it doesn't
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exist.
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.. attribute:: verify_exists=False
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If ``verify_exists`` is ``True``, this validator checks that the url actually
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exists.
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.. attribute:: validator_user_agent=URL_VALIDATOR_USER_AGENT
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If ``verify_exists`` is ``True``, use validator_user_agent as the User-agent
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for the request. Defaults to ``settings.URL_VALIDATOR_USER_AGENT``.
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``validate_email``
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------------------
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A ``RegexValidator`` instance that ensures a value looks like an email address.
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``validate_slug``
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-----------------
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A ``RegexValidator`` instance that ensures a value consists of only
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letters, numbers, underscores, or hyphens.
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``validate_ipv4_address``
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-------------------------
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A ``RegexValidator`` instance that ensures a value looks like an IPv4 address.
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``validate_comma_separated_integer_list``
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-----------------------------------------
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A ``RegexValidator`` instance that ensures a value is a comma separated list
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of integers.
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``MaxValueValidator``
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---------------------
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.. class:: MaxValueValidator(max_value)
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Raises a ``ValidationError`` with a code of ``'max_value'`` if ``value`` is
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greater than ``max_value``.
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``MinValueValidator``
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---------------------
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.. class:: MinValueValidator(min_value)
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Raises a ``ValidationError`` with a code of ``'min_value'`` if ``value`` is
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less than ``min_value``.
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``MaxLengthValidator``
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----------------------
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.. class:: MaxLengthValidator(max_length)
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Raises a ``ValidationError`` with a code of ``'max_length'`` if the length of
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``value`` is greater than ``max_length``.
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``MinLengthValidator``
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----------------------
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.. class:: MinLengthValidator(min_length)
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Raises a ``ValidationError`` with a code of ``'min_length'`` if the length of
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``value`` is less than ``min_length``.
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