Length

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

Applies to property or method
Options
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:

  • Annotations
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
    // 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;
}
  • YAML
    1
2
3
4
5
6
7
8
9
    # 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'
  • XML
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
    <!-- 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>
  • PHP
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
    // 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

Deprecated since version 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

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

It defines the validation group or groups this constraint belongs to. 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.