validation.md

Symfony validation

Install validator component:

composer require validator

Symfony's validation is interesting because you don't apply the validation rules to the form. You apply them to your class via annotations.

See supported constraints.

Suppose that we have src/Entity/Article.php:

use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity(repositoryClass="App\Repository\ArticleRepository")
 */
class Article
{
    // Annotation here ...
    private $some_field;
}

Length

/**
 * @ORM\Column(type="string", length=255)
 * @Assert\Length(
 *      min = 5,
 *      max = 50,
 *      minMessage = "Title must be at least {{ limit }} characters long",
 *      maxMessage = "Title cannot be longer than {{ limit }} characters"
 * )
 */
private $title;

If you try to submit the form with big title you'll get the custom error message: Title cannot be longer than 50 characters.

Email

/**
 * @ORM\Column(type="string", length=180, unique=true)
 * @Assert\Email()
 */
private $email;

NotBlank

/**
 * @ORM\Column(type="string", length=180, unique=true)
 * @Assert\NotBlank(message="Please enter an email")
 */
private $email;

The Callback Constraint

This is the tool when you need to do something totally custom. Create a method in your class and add @Assert\Callback() above it. Then, during validation, Symfony will call your method.

/**
 * @Assert\Callback
 */
public function validate(ExecutionContextInterface $context, $payload)
{
    if (stripos($this->getTitle(), 'bad word') !== false) {
        $context->buildViolation('Do not use bad word for title!')
            ->atPath('title')
            ->addViolation();
    }
}

Important: Because the callback lives inside your entity, you don't have access to any services. So, you couldn't make a query, for example. If Callback doesn't work, the solution that always works is to create your very own custom validation constraint.

UniqueEntity

We apply unique validation to Entity:

/**
 * @ORM\Entity(repositoryClass="App\Repository\UserRepository")
 * @UniqueEntity(
 *     fields={"email"},
 *     message="I think you're already registered!"
 * )
 */
class User implements UserInterface
{

Add validation to FormType

We usually add validation rules via annotations on a class. But, if you have a field that's not mapped, you can add its validation rules directly to the form field via a constraints array option. What do you put inside? Remember how each annotation is represented by a concrete class? That's the key! Instantiate those as objects here: new NotBlank(). To pass options, use an array and set message to Choose a password!.

use Symfony\Component\Validator\Constraints\Length;
use Symfony\Component\Validator\Constraints\NotBlank;

class UserRegistrationFormType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('email')
            // don't use password: avoid EVER setting that on a
            // field that might be persisted
            ->add('plainPassword', PasswordType::class, [
                'mapped' => false,
                'constraints' => [
                    new NotBlank([
                        'message' => 'Choose a password!'
                    ]),
                    new Length([
                        'min' => 5,
                        'minMessage' => 'Come on, you can think of a password longer than that!'
                    ])
                ]
            ]);
        ;
    }
    
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'data_class' => User::class,
        ]);
    }
}