Validators

For example, here’s a validator that only allows even numbers:

You can add this to a model field via the field’s validators argument:

Because values are converted to Python before validators are run, you can even use the same validator with forms:

You can also use a class with a __call__() method for more complex or configurable validators. , for example, uses this technique. If a class-based validator is used in the validators model field option, you should make sure it is by adding deconstruct() and __eq__() methods.

See the for more information on how validators are run in forms, and Validating objects for how they’re run in models. Note that validators will not be run automatically when you save a model, but if you are using a , it will run your validators on any fields that are included in your form. See the ModelForm documentation for information on how model validation interacts with forms.

The module contains a collection of callable validators for use with model and form fields. They’re used internally but are available for use with your own fields, too. They can be used in addition to, or in lieu of custom field.clean() methods.

class RegexValidator(regex=None, message=None, code=None, inverse_match=None, flags=0)[source]

A searches the provided value for a given regular expression with re.search(). By default, raises a with message and if a match is not found. Its behavior can be inverted by setting inverse_match to True, in which case the is raised when a match is found.

• regex

  The regular expression pattern to search for within the provided value, using re.search(). This may be a string or a pre-compiled regular expression created with . Defaults to the empty string, which will be found in every possible value.

• message

  The error message used by ValidationError if validation fails. Defaults to "Enter a valid value".

• code

  The error code used by if validation fails. Defaults to "invalid".

• flags

  The regex flags used when compiling the regular expression string . If regex is a pre-compiled regular expression, and is overridden, TypeError is raised. Defaults to 0.

EmailValidator

class EmailValidator(message=None, code=None, allowlist=None)[source]

• message

  The error message used by if validation fails. Defaults to "Enter a valid email address".

• code

  The error code used by ValidationError if validation fails. Defaults to "invalid".

• Allowlist of email domains. By default, a regular expression (the domain_regex attribute) is used to validate whatever appears after the @ sign. However, if that string appears in the allowlist, this validation is bypassed. If not provided, the default allowlist is ['localhost']. Other domains that don’t contain a dot won’t pass validation, so you’d need to add them to the allowlist as necessary.

URLValidator

class URLValidator(schemes=None, regex=None, message=None, code=None)[source]

A subclass that ensures a value looks like a URL, and raises an error code of 'invalid' if it doesn’t.

Loopback addresses and reserved IP spaces are considered valid. Literal IPv6 addresses (RFC 3986#section-3.2.2) and Unicode domains are both supported.

In addition to the optional arguments of its parent class, URLValidator accepts an extra optional attribute:

• schemes

  URL/URI scheme list to validate against. If not provided, the default list is ['http', 'https', 'ftp', 'ftps']. As a reference, the IANA website provides a full list of valid URI schemes.

validate_email

validate_email

An EmailValidator instance without any customizations.

validate_slug

validate_slug

A RegexValidator instance that ensures a value consists of only letters, numbers, underscores or hyphens.

validate_unicode_slug

validate_unicode_slug

A RegexValidator instance that ensures a value consists of only Unicode letters, numbers, underscores, or hyphens.

validate_ipv4_address

A RegexValidator instance that ensures a value looks like an IPv4 address.

validate_ipv6_address

validate_ipv6_address[source]

Uses django.utils.ipv6 to check the validity of an IPv6 address.

validate_ipv46_address

validate_ipv46_address[source]

Uses both validate_ipv4_address and validate_ipv6_address to ensure a value is either a valid IPv4 or IPv6 address.

validate_comma_separated_integer_list

validate_comma_separated_integer_list

A RegexValidator instance that ensures a value is a comma-separated list of integers.

int_list_validator

int_list_validator(sep=’,’, message=None, code=’invalid’, allow_negative=False)[source]

Returns a instance that ensures a string consists of integers separated by sep. It allows negative integers when allow_negative is True.

MaxValueValidator

Raises a with a code of 'max_value' if value is greater than limit_value, which may be a callable.

class MinValueValidator(limit_value, message=None)[source]

Raises a with a code of if value is less than limit_value, which may be a callable.

MaxLengthValidator

class MaxLengthValidator(limit_value, message=None)

Raises a ValidationError with a code of 'max_length' if the length of value is greater than limit_value, which may be a callable.

MinLengthValidator

class MinLengthValidator(limit_value, message=None)[source]

Raises a with a code of 'min_length' if the length of value is less than limit_value, which may be a callable.

DecimalValidator

class DecimalValidator(max_digits, decimal_places)

Raises ValidationError with the following codes:

• 'max_digits' if the number of digits is larger than max_digits.
• 'max_decimal_places' if the number of decimals is larger than decimal_places.
• 'max_whole_digits' if the number of whole digits is larger than the difference between max_digits and decimal_places.

FileExtensionValidator

class FileExtensionValidator(allowed_extensions, message, code)[source]

Raises a with a code of 'invalid_extension' if the extension of value.name (value is a File) isn’t found in allowed_extensions. The extension is compared case-insensitively with allowed_extensions.

Warning

Don’t rely on validation of the file extension to determine a file’s type. Files can be renamed to have any extension no matter what data they contain.

validate_image_file_extension

validate_image_file_extension[source]

Uses Pillow to ensure that value.name (value is a ) has a valid image extension.

class ProhibitNullCharactersValidator(message=None, code=None)

Raises a ValidationError if str(value) contains one or more nulls characters ('\x00').

• message

  The error message used by if validation fails. Defaults to "Null characters are not allowed.".

• code

  The error code used by ValidationError if validation fails. Defaults to "null_characters_not_allowed".

StepValueValidator

New in Django 4.1.

class StepValueValidator(limit_value, message=None)[source]