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How to Validate Raw Values (Scalar Values and Arrays)

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How to Validate Raw Values (Scalar Values and Arrays)¶

Usually you will be validating entire objects. But sometimes, you just want to validate a simple value - like to verify that a string is a valid email address. To achieve this, you can instantiate the validator directly. From inside a controller, it looks like this:

// ...
use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Validator\ValidatorInterface;

// ...
public function addEmail($email, ValidatorInterface $validator)
{
    $emailConstraint = new Assert\Email();
    // all constraint "options" can be set this way
    $emailConstraint->message = 'Invalid email address';

    // use the validator to validate the value
    $errors = $validator->validate(
        $email,
        $emailConstraint
    );

    if (0 === count($errors)) {
        // ... this IS a valid email address, do something
    } else {
        // this is *not* a valid email address
        $errorMessage = $errors[0]->getMessage();

        // ... do something with the error
    }

    // ...
}

By calling validate() on the validator, you can pass in a raw value and the constraint object that you want to validate that value against. A full list of the available constraints - as well as the full class name for each constraint - is available in the constraints reference section.

Validation of arrays is possible using the Collection constraint:

use Symfony\Component\Validator\Validation;
use Symfony\Component\Validator\Constraints as Assert;

$validator = Validation::createValidator();

$constraint = new Assert\Collection(array(
    // the keys correspond to the keys in the input array
    'name' => new Assert\Collection(array(
      'first_name' => new Assert\Length(array('min' => 101)),
      'last_name' => new Assert\Length(array('min' => 1)),
    )),
    'email' => new Assert\Email(),
    'simple' => new Assert\Length(array('min' => 102)),
    'gender' => new Assert\Choice(array(3, 4)),
    'file' => new Assert\File(),
    'password' => new Assert\Length(array('min' => 60)),
));

$violations = $validator->validate($input, $constraint);

The validate() method returns a ConstraintViolationList object, which acts just like an array of errors. Each error in the collection is a ConstraintViolation object, which holds the error message on its getMessage() method.

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