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398 lines
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398 lines
14 KiB
Plaintext
==========
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Validators
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==========
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.. module:: django.core.validators
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:synopsis: Validation utilities and base classes
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Writing validators
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==================
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A validator is a callable that takes a value and raises a
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:exc:`~django.core.exceptions.ValidationError` if it doesn't meet some
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criteria. Validators can be useful for reusing validation logic between
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different types of fields.
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For example, here's a validator that only allows even numbers::
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from django.core.exceptions import ValidationError
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from django.utils.translation import gettext_lazy as _
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def validate_even(value):
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if value % 2 != 0:
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raise ValidationError(
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_("%(value)s is not an even number"),
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params={"value": value},
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)
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You can add this to a model field via the field's :attr:`~django.db.models.Field.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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Because 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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You can also use a class with a ``__call__()`` method for more complex or
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configurable validators. :class:`RegexValidator`, for example, uses this
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technique. If a class-based validator is used in the
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:attr:`~django.db.models.Field.validators` model field option, you should make
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sure it is :ref:`serializable by the migration framework
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<migration-serializing>` by adding :ref:`deconstruct()
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<custom-deconstruct-method>` and ``__eq__()`` methods.
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How validators are run
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======================
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See the :doc:`form validation </ref/forms/validation>` for more information on
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how validators are run in forms, and :ref:`Validating objects
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<validating-objects>` for how they're run in models. Note that validators will
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not be run automatically when you save a model, but if you are using a
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:class:`~django.forms.ModelForm`, it will run your validators on any fields
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that are included in your form. See the
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:doc:`ModelForm documentation </topics/forms/modelforms>` for information on
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how model validation interacts with forms.
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Built-in validators
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===================
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The :mod:`django.core.validators` module contains a collection of callable
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validators for use with model and form fields. They're used internally but
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are available for use with your own fields, too. They can be used in addition
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to, or in lieu of custom ``field.clean()`` methods.
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``RegexValidator``
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------------------
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.. class:: RegexValidator(regex=None, message=None, code=None, inverse_match=None, flags=0)
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:param regex: If not ``None``, overrides :attr:`regex`. Can be a regular
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expression string or a pre-compiled regular expression.
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:param message: If not ``None``, overrides :attr:`.message`.
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:param code: If not ``None``, overrides :attr:`code`.
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:param inverse_match: If not ``None``, overrides :attr:`inverse_match`.
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:param flags: If not ``None``, overrides :attr:`flags`. In that case,
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:attr:`regex` must be a regular expression string, or
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:exc:`TypeError` is raised.
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A :class:`RegexValidator` searches the provided ``value`` for a given
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regular expression with :func:`re.search`. By default, raises a
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:exc:`~django.core.exceptions.ValidationError` with :attr:`message` and
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:attr:`code` if a match **is not** found. Its behavior can be inverted by
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setting :attr:`inverse_match` to ``True``, in which case the
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:exc:`~django.core.exceptions.ValidationError` is raised when a match
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**is** found.
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.. attribute:: regex
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The regular expression pattern to search for within the provided
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``value``, using :func:`re.search`. This may be a string or a
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pre-compiled regular expression created with :func:`re.compile`.
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Defaults to the empty string, which will be found in every possible
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``value``.
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.. attribute:: message
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The error message used by
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:exc:`~django.core.exceptions.ValidationError` if validation fails.
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Defaults to ``"Enter a valid value"``.
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.. attribute:: code
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The error code used by :exc:`~django.core.exceptions.ValidationError`
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if validation fails. Defaults to ``"invalid"``.
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.. attribute:: inverse_match
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The match mode for :attr:`regex`. Defaults to ``False``.
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.. attribute:: flags
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The :ref:`regex flags <python:contents-of-module-re>` used when
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compiling the regular expression string :attr:`regex`. If :attr:`regex`
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is a pre-compiled regular expression, and :attr:`flags` is overridden,
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:exc:`TypeError` is raised. Defaults to ``0``.
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``EmailValidator``
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------------------
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.. class:: EmailValidator(message=None, code=None, allowlist=None)
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:param message: If not ``None``, overrides :attr:`.message`.
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:param code: If not ``None``, overrides :attr:`code`.
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:param allowlist: If not ``None``, overrides :attr:`allowlist`.
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An :class:`EmailValidator` ensures that a value looks like an email, and
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raises a :exc:`~django.core.exceptions.ValidationError` with
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:attr:`message` and :attr:`code` if it doesn't. Values longer than 320
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characters are always considered invalid.
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.. attribute:: message
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The error message used by
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:exc:`~django.core.exceptions.ValidationError` if validation fails.
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Defaults to ``"Enter a valid email address"``.
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.. attribute:: code
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The error code used by :exc:`~django.core.exceptions.ValidationError`
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if validation fails. Defaults to ``"invalid"``.
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.. attribute:: allowlist
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Allowlist of email domains. By default, a regular expression (the
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``domain_regex`` attribute) is used to validate whatever appears after
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the ``@`` sign. However, if that string appears in the ``allowlist``,
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this validation is bypassed. If not provided, the default ``allowlist``
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is ``['localhost']``. Other domains that don't contain a dot won't pass
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validation, so you'd need to add them to the ``allowlist`` as
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necessary.
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``DomainNameValidator``
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-----------------------
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.. versionadded:: 5.1
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.. class:: DomainNameValidator(accept_idna=True, message=None, code=None)
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A :class:`RegexValidator` subclass that ensures a value looks like a domain
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name. Values longer than 255 characters are always considered invalid. IP
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addresses are not accepted as valid domain names.
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In addition to the optional arguments of its parent :class:`RegexValidator`
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class, ``DomainNameValidator`` accepts an extra optional attribute:
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.. attribute:: accept_idna
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Determines whether to accept internationalized domain names, that is,
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domain names that contain non-ASCII characters. Defaults to ``True``.
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``URLValidator``
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----------------
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.. class:: URLValidator(schemes=None, regex=None, message=None, code=None)
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A :class:`RegexValidator` subclass that ensures a value looks like a URL,
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and raises an error code of ``'invalid'`` if it doesn't. Values longer than
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:attr:`max_length` characters are always considered invalid.
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Loopback addresses and reserved IP spaces are considered valid. Literal
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IPv6 addresses (:rfc:`3986#section-3.2.2`) and Unicode domains are both
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supported.
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In addition to the optional arguments of its parent :class:`RegexValidator`
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class, ``URLValidator`` accepts an extra optional attribute:
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.. attribute:: schemes
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URL/URI scheme list to validate against. If not provided, the default
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list is ``['http', 'https', 'ftp', 'ftps']``. As a reference, the IANA
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website provides a full list of `valid URI schemes`_.
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.. _valid URI schemes: https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
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.. warning::
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Values starting with ``file:///`` will not pass validation even
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when the ``file`` scheme is provided. Valid values must contain a
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host.
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.. attribute:: max_length
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The maximum length of values that could be considered valid. Defaults
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to 2048 characters.
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``validate_email``
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------------------
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.. data:: validate_email
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An :class:`EmailValidator` instance without any customizations.
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``validate_domain_name``
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------------------------
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.. versionadded:: 5.1
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.. data:: validate_domain_name
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A :class:`DomainNameValidator` instance without any customizations.
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``validate_slug``
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-----------------
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.. data:: validate_slug
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A :class:`RegexValidator` instance that ensures a value consists of only
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letters, numbers, underscores or hyphens.
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``validate_unicode_slug``
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-------------------------
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.. data:: validate_unicode_slug
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A :class:`RegexValidator` instance that ensures a value consists of only
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Unicode letters, numbers, underscores, or hyphens.
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``validate_ipv4_address``
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-------------------------
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.. data:: validate_ipv4_address
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A :class:`RegexValidator` instance that ensures a value looks like an IPv4
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address.
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``validate_ipv6_address``
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-------------------------
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.. data:: validate_ipv6_address
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Uses ``django.utils.ipv6`` to check the validity of an IPv6 address.
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``validate_ipv46_address``
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--------------------------
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.. data:: validate_ipv46_address
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Uses both ``validate_ipv4_address`` and ``validate_ipv6_address`` to
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ensure a value is either a valid IPv4 or IPv6 address.
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``validate_comma_separated_integer_list``
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-----------------------------------------
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.. data:: validate_comma_separated_integer_list
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A :class:`RegexValidator` instance that ensures a value is a
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comma-separated list of integers.
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``int_list_validator``
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----------------------
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.. function:: int_list_validator(sep=',', message=None, code='invalid', allow_negative=False)
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Returns a :class:`RegexValidator` instance that ensures a string consists
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of integers separated by ``sep``. It allows negative integers when
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``allow_negative`` is ``True``.
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``MaxValueValidator``
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---------------------
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.. class:: MaxValueValidator(limit_value, message=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'max_value'`` if ``value`` is greater than ``limit_value``, which may be
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a callable.
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``MinValueValidator``
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---------------------
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.. class:: MinValueValidator(limit_value, message=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'min_value'`` if ``value`` is less than ``limit_value``, which may be a
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callable.
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``MaxLengthValidator``
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----------------------
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.. class:: MaxLengthValidator(limit_value, message=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'max_length'`` if the length of ``value`` is greater than
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``limit_value``, which may be a callable.
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``MinLengthValidator``
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----------------------
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.. class:: MinLengthValidator(limit_value, message=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'min_length'`` if the length of ``value`` is less than ``limit_value``,
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which may be a callable.
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``DecimalValidator``
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--------------------
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.. class:: DecimalValidator(max_digits, decimal_places)
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Raises :exc:`~django.core.exceptions.ValidationError` with the following
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codes:
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- ``'max_digits'`` if the number of digits is larger than ``max_digits``.
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- ``'max_decimal_places'`` if the number of decimals is larger than
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``decimal_places``.
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- ``'max_whole_digits'`` if the number of whole digits is larger than
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the difference between ``max_digits`` and ``decimal_places``.
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``FileExtensionValidator``
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--------------------------
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.. class:: FileExtensionValidator(allowed_extensions, message, code)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'invalid_extension'`` if the extension of ``value.name`` (``value`` is
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a :class:`~django.core.files.File`) isn't found in ``allowed_extensions``.
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The extension is compared case-insensitively with ``allowed_extensions``.
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.. warning::
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Don't rely on validation of the file extension to determine a file's
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type. Files can be renamed to have any extension no matter what data
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they contain.
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``validate_image_file_extension``
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---------------------------------
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.. data:: validate_image_file_extension
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Uses Pillow to ensure that ``value.name`` (``value`` is a
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:class:`~django.core.files.File`) has `a valid image extension
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<https://pillow.readthedocs.io/en/latest/handbook/image-file-formats.html>`_.
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``ProhibitNullCharactersValidator``
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-----------------------------------
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.. class:: ProhibitNullCharactersValidator(message=None, code=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` if ``str(value)``
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contains one or more null characters (``'\x00'``).
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:param message: If not ``None``, overrides :attr:`.message`.
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:param code: If not ``None``, overrides :attr:`code`.
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.. attribute:: message
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The error message used by
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:exc:`~django.core.exceptions.ValidationError` if validation fails.
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Defaults to ``"Null characters are not allowed."``.
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.. attribute:: code
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The error code used by :exc:`~django.core.exceptions.ValidationError`
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if validation fails. Defaults to ``"null_characters_not_allowed"``.
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``StepValueValidator``
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----------------------
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.. class:: StepValueValidator(limit_value, message=None, offset=None)
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Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
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``'step_size'`` if ``value`` is not an integral multiple of
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``limit_value``, which can be a float, integer or decimal value or a
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callable. When ``offset`` is set, the validation occurs against
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``limit_value`` plus ``offset``. For example, for
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``StepValueValidator(3, offset=1.4)`` valid values include ``1.4``,
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``4.4``, ``7.4``, ``10.4``, and so on.
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