How to validate unique entities in an entity collection in symfony2

Question

I have an entity with a OneToMany relation to another entity, when I persist the parent entity I want to ensure the children contain no duplicates.

Here\'s the class

Answer 1

For Symfony 4.3(only tested version) you can use my custom validator. Prefered way of usage is as annotaion on validated collection:

use App\Validator\Constraints as App;

...

/**
 * @ORM\OneToMany
 *
 * @App\UniqueProperty(
 *     propertyPath="entityProperty"
 * )
 */
private $entities;

Difference between Julien and my solution is, that my Constraint is defined on validated Collection instead on element of Collection itself.

Constraint:

#src/Validator/Constraints/UniqueProperty.php

Validator:

#src/Validator/Constraints/UniquePropertyValidator.php
propertyAccessor = PropertyAccess::createPropertyAccessor();
    }

    /**
     * @param mixed $value
     * @param Constraint $constraint
     * @throws \Exception
     */
    public function validate($value, Constraint $constraint)
    {
        if (!$constraint instanceof UniqueProperty) {
            throw new UnexpectedTypeException($constraint, UniqueProperty::class);
        }

        if (null === $value) {
            return;
        }

        if (!\is_array($value) && !$value instanceof \IteratorAggregate) {
            throw new UnexpectedValueException($value, 'array|IteratorAggregate');
        }

        if ($constraint->propertyPath === null) {
            throw new \Exception('Option propertyPath can not be null');
        }

        $propertyValues = [];
        foreach ($value as $key => $element) {
            $propertyValue = $this->propertyAccessor->getValue($element, $constraint->propertyPath);
            if (in_array($propertyValue, $propertyValues, true)) {
                $this->context->buildViolation($constraint->message)
                    ->atPath(sprintf('[%s]', $key))
                    ->addViolation();
            }

            $propertyValues[] = $propertyValue;
        }
    }
}