---
title: "Validators"
version: 2.0
locale: es
source: https://docs.djangoproject.com/es/2.0/ref/validators/
canonical: https://djangodocs.dev/es/2.0/ref/validators/
---
# Validators

## Writing validators

A validator is a callable that takes a value and raises a
[`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) if it doesn’t meet some
criteria. Validators can be useful for re-using validation logic between
different types of fields.

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

```
from django.core.exceptions import ValidationError
from django.utils.translation import gettext_lazy as _

def validate_even(value):
    if value % 2 != 0:
        raise ValidationError(
            _('%(value)s is not an even number'),
            params={'value': value},
        )
```

You can add this to a model field via the field’s [`validators`](/es/2.0/ref/models/fields/#django.db.models.Field.validators)
argument:

```
from django.db import models

class MyModel(models.Model):
    even_field = models.IntegerField(validators=[validate_even])
```

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

```
from django import forms

class MyForm(forms.Form):
    even_field = forms.IntegerField(validators=[validate_even])
```

You can also use a class with a `__call__()` method for more complex or
configurable validators. [`RegexValidator`](#django.core.validators.RegexValidator), for example, uses this
technique. If a class-based validator is used in the
[`validators`](/es/2.0/ref/models/fields/#django.db.models.Field.validators) model field option, you should make
sure it is [serializable by the migration framework](/es/2.0/topics/migrations/#migration-serializing) by adding [deconstruct()](/es/2.0/topics/migrations/#custom-deconstruct-method) and `__eq__()` methods.

## How validators are run

See the [form validation](/es/2.0/ref/forms/validation/) for more information on
how validators are run in forms, and [Validating objects](/es/2.0/ref/models/instances/#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
[`ModelForm`](/es/2.0/topics/forms/modelforms/#django.forms.ModelForm), it will run your validators on any fields
that are included in your form. See the
[ModelForm documentation](/es/2.0/topics/forms/modelforms/) for information on
how model validation interacts with forms.

## Built-in validators

The [`django.core.validators`](#module-django.core.validators) 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.

### `RegexValidator`

#### `class RegexValidator(regex=None, message=None, code=None, inverse_match=None, flags=0)`

**Parámetros:** - `regex` – If not `None`, overrides [`regex`](#django.core.validators.RegexValidator.regex). Can be a regular
  expression string or a pre-compiled regular expression.
- `message` – If not `None`, overrides [`message`](#django.core.validators.RegexValidator.message).
- `code` – If not `None`, overrides [`code`](#django.core.validators.RegexValidator.code).
- `inverse_match` – If not `None`, overrides [`inverse_match`](#django.core.validators.RegexValidator.inverse_match).
- `flags` – If not `None`, overrides [`flags`](#django.core.validators.RegexValidator.flags). In that case,
  [`regex`](#django.core.validators.RegexValidator.regex) must be a regular expression string, or
  [`TypeError`](https://docs.python.org/3/library/exceptions.html#TypeError) is raised.

#### `regex`

The regular expression pattern to search for within the provided
`value`, or a pre-compiled regular expression. By default, raises a
[`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with [`message`](#django.core.validators.RegexValidator.message)
and [`code`](#django.core.validators.RegexValidator.code) if a match is not found. That standard behavior can
be reversed by setting [`inverse_match`](#django.core.validators.RegexValidator.inverse_match) to `True`, in which case
the [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) is raised when a
match **is** found. By default, matches any string (including an empty
string).

#### `message`

The error message used by
[`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) if validation fails.
Defaults to `"Enter a valid value"`.

#### `code`

The error code used by [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError)
if validation fails. Defaults to `"invalid"`.

#### `inverse_match`

The match mode for [`regex`](#django.core.validators.RegexValidator.regex). Defaults to `False`.

#### `flags`

The flags used when compiling the regular expression string
[`regex`](#django.core.validators.RegexValidator.regex). If [`regex`](#django.core.validators.RegexValidator.regex) is a pre-compiled regular expression,
and [`flags`](#django.core.validators.RegexValidator.flags) is overridden, [`TypeError`](https://docs.python.org/3/library/exceptions.html#TypeError) is raised. Defaults
to `0`.

### `EmailValidator`

#### `class EmailValidator(message=None, code=None, whitelist=None)`

**Parámetros:** - `message` – If not `None`, overrides [`message`](#django.core.validators.EmailValidator.message).
- `code` – If not `None`, overrides [`code`](#django.core.validators.EmailValidator.code).
- `whitelist` – If not `None`, overrides [`whitelist`](#django.core.validators.EmailValidator.whitelist).

#### `message`

The error message used by
[`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) if validation fails.
Defaults to `"Enter a valid email address"`.

#### `code`

The error code used by [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError)
if validation fails. Defaults to `"invalid"`.

#### `whitelist`

Whitelist of email domains to allow. 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 whitelist, this
validation is bypassed. If not provided, the default whitelist is
`['localhost']`. Other domains that don’t contain a dot won’t pass
validation, so you’d need to whitelist them as necessary.

### `URLValidator`

#### `class URLValidator(schemes=None, regex=None, message=None, code=None)`

A [`RegexValidator`](#django.core.validators.RegexValidator) 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 2732**](https://datatracker.ietf.org/doc/html/rfc2732.html)) and unicode domains are both supported.

In addition to the optional arguments of its parent [`RegexValidator`](#django.core.validators.RegexValidator)
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](https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml).

### `validate_email`

#### `validate_email`

An [`EmailValidator`](#django.core.validators.EmailValidator) instance without any customizations.

### `validate_slug`

#### `validate_slug`

A [`RegexValidator`](#django.core.validators.RegexValidator) instance that ensures a value consists of only
letters, numbers, underscores or hyphens.

### `validate_unicode_slug`

#### `validate_unicode_slug`

A [`RegexValidator`](#django.core.validators.RegexValidator) instance that ensures a value consists of only
Unicode letters, numbers, underscores, or hyphens.

### `validate_ipv4_address`

#### `validate_ipv4_address`

A [`RegexValidator`](#django.core.validators.RegexValidator) instance that ensures a value looks like an IPv4
address.

### `validate_ipv6_address`

#### `validate_ipv6_address`

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

### `validate_ipv46_address`

#### `validate_ipv46_address`

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`](#django.core.validators.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)`

Returns a [`RegexValidator`](#django.core.validators.RegexValidator) instance that ensures a string consists
of integers separated by `sep`. It allows negative integers when
`allow_negative` is `True`.

### `MaxValueValidator`

#### `class MaxValueValidator(max_value, message=None)`

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with a code of
`'max_value'` if `value` is greater than `max_value`.

### `MinValueValidator`

#### `class MinValueValidator(min_value, message=None)`

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with a code of
`'min_value'` if `value` is less than `min_value`.

### `MaxLengthValidator`

#### `class MaxLengthValidator(max_length, message=None)`

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with a code of
`'max_length'` if the length of `value` is greater than `max_length`.

### `MinLengthValidator`

#### `class MinLengthValidator(min_length, message=None)`

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with a code of
`'min_length'` if the length of `value` is less than `min_length`.

### `DecimalValidator`

#### `class DecimalValidator(max_digits, decimal_places)`

Raises [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.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)`

> **New in Django 1.11**

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) with a code of
`'invalid_extension'` if the extension of `value.name` (`value` is
a [`File`](/es/2.0/ref/files/file/#django.core.files.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`

> **New in Django 1.11**

Uses Pillow to ensure that `value.name` (`value` is a
[`File`](/es/2.0/ref/files/file/#django.core.files.File)) has [a valid image extension](https://pillow.readthedocs.io/en/latest/handbook/image-file-formats.html).

### `ProhibitNullCharactersValidator`

#### `class ProhibitNullCharactersValidator(message=None, code=None)`

> **New in Django 2.0**

Raises a [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) if `str(value)`
contains one or more nulls characters (`'\x00'`).

**Parámetros:** - `message` – If not `None`, overrides [`message`](#django.core.validators.ProhibitNullCharactersValidator.message).
- `code` – If not `None`, overrides [`code`](#django.core.validators.ProhibitNullCharactersValidator.code).

#### `message`

The error message used by
[`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError) if validation fails.
Defaults to `"Null characters are not allowed."`.

#### `code`

The error code used by [`ValidationError`](/es/2.0/ref/exceptions/#django.core.exceptions.ValidationError)
if validation fails. Defaults to `"null_characters_not_allowed"`.