Length

Validates that a given string length is between some minimum and maximum value.

Applies to	property or method
Class	Length
Validator	LengthValidator

Basic Usage

To verify that the firstName field length of a class is between 2 and 50, you might add the following:

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        // src/Entity/Participant.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Participant
{
    /**
     * @Assert\Length(
     *      min = 2,
     *      max = 50,
     *      minMessage = "Your first name must be at least {{ limit }} characters long",
     *      maxMessage = "Your first name cannot be longer than {{ limit }} characters"
     * )
     */
    protected $firstName;
}
    

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        // src/Entity/Participant.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Participant
{
    #[Assert\Length(
        min: 2,
        max: 50,
        minMessage: 'Your first name must be at least {{ limit }} characters long',
        maxMessage: 'Your first name cannot be longer than {{ limit }} characters',
    )]
    protected $firstName;
}
    

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        # config/validator/validation.yaml
App\Entity\Participant:
    properties:
        firstName:
            - Length:
                min: 2
                max: 50
                minMessage: 'Your first name must be at least {{ limit }} characters long'
                maxMessage: 'Your first name cannot be longer than {{ limit }} characters'
    

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        <!-- config/validator/validation.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="App\Entity\Participant">
        <property name="firstName">
            <constraint name="Length">
                <option name="min">2</option>
                <option name="max">50</option>
                <option name="minMessage">
                    Your first name must be at least {{ limit }} characters long
                </option>
                <option name="maxMessage">
                    Your first name cannot be longer than {{ limit }} characters
                </option>
            </constraint>
        </property>
    </class>
</constraint-mapping>
    

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        // src/Entity/Participant.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Mapping\ClassMetadata;

class Participant
{
    public static function loadValidatorMetadata(ClassMetadata $metadata)
    {
        $metadata->addPropertyConstraint('firstName', new Assert\Length([
            'min' => 2,
            'max' => 50,
            'minMessage' => 'Your first name must be at least {{ limit }} characters long',
            'maxMessage' => 'Your first name cannot be longer than {{ limit }} characters',
        ]));
    }
}
    

Note

As with most of the other constraints, null and empty strings are considered valid values. This is to allow them to be optional values. If the value is mandatory, a common solution is to combine this constraint with NotBlank.

Options

`allowEmptyString`

type: boolean default: false

5.2

The allowEmptyString option is deprecated since Symfony 5.2. If you want to allow empty strings too, combine the Length constraint with the Blank constraint inside the AtLeastOneOf constraint.

If set to true, empty strings are considered valid (which is the same behavior as previous Symfony versions). The default false value considers empty strings not valid.

Caution

This option does not have any effect when no minimum length is given.

`charset`

type: string default: UTF-8

The charset to be used when computing value's length with the mb_check_encoding and mb_strlen PHP functions.

`charsetMessage`

type: string default: This value does not match the expected {{ charset }} charset.

The message that will be shown if the value is not using the given charset.

You can use the following parameters in this message:

Parameter	Description
`{{ charset }}`	The expected charset
`{{ value }}`	The current (invalid) value

`exactly`

type: integer

This option is the exact length value. Validation will fail if the given value's length is not exactly equal to this value.

Note

This option is the one being set by default when using the Length constraint without passing any named argument to it. This means that for example, @Assert\Length(20) and @Assert\Length(exactly=20) are equivalent, as well as #[Assert\Length(20)] and #[Assert\Length(exactly: 20)].

5.2

The named argument exactly was introduced in Symfony 5.2.

`exactMessage`

type: string default: This value should have exactly {{ limit }} characters.

The message that will be shown if min and max values are equal and the underlying value's length is not exactly this value.

You can use the following parameters in this message:

Parameter	Description
`{{ limit }}`	The exact expected length
`{{ value }}`	The current (invalid) value

`groups`

type: array | string default: null

It defines the validation group or groups of this constraint. Read more about validation groups.

`max`

type: integer

This option is the "max" length value. Validation will fail if the given value's length is greater than this max value.

This option is required when the min option is not defined.

`maxMessage`

type: string default: This value is too long. It should have {{ limit }} characters or less.

The message that will be shown if the underlying value's length is more than the max option.

You can use the following parameters in this message:

Parameter	Description
`{{ limit }}`	The expected maximum length
`{{ value }}`	The current (invalid) value

`min`

type: integer

This option is the "min" length value. Validation will fail if the given value's length is less than this min value.

This option is required when the max option is not defined.

It is important to notice that NULL values and empty strings are considered valid no matter if the constraint required a minimum length. Validators are triggered only if the value is not blank.

`minMessage`

type: string default: This value is too short. It should have {{ limit }} characters or more.

The message that will be shown if the underlying value's length is less than the min option.

You can use the following parameters in this message:

Parameter	Description
`{{ limit }}`	The expected minimum length
`{{ value }}`	The current (invalid) value

`normalizer`

type: a PHP callable default: null

This option allows to define the PHP callable applied to the given value before checking if it is valid.

For example, you may want to pass the 'trim' string to apply the trim PHP function in order to ignore leading and trailing whitespace during validation.

`payload`

type: mixed default: null

This option can be used to attach arbitrary domain-specific data to a constraint. The configured payload is not used by the Validator component, but its processing is completely up to you.

For example, you may want to use several error levels to present failed constraints differently in the front-end depending on the severity of the error.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.

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