UniqueDto validator

Readme.md

It can

• properly deal with multi-fields uniqueness checks (and composite PKs)
• use symfony's property path or directly private properties
• does not cause hydration when checking
• allows to optionally map to existing entity (by having it as property) or by mapping id fields (or none at all so any matching record will trigger a failure)
• allows to re-map fields between DTO and entity (eg. fields={"display_name": "username"}). Combined with sf property accessor this allows for "virtual properties". This also works for id fields
• load the violating record to show in debug panel. Example http://prntscr.com/i3ifbn
• not get confused if multiple violating records are found

Things to improve:

• port $ignoreNull check over from UniqueEntity (I have no idea what it does)
• check if id fields are actually properly specified
• tests (will probably need help)

Simple example (doesn't feature all possible uses).php

<?php
declare(strict_types=1);

namespace App\Form\Dto;

use App\Validator\Constraints\UniqueDto;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @UniqueDto(entityClass="App\Entity\User", fields={"username"}, message="Username already taken")
 * @UniqueDto(entityClass="App\Entity\User", fields={"email"}, message="Email already used")
 */
class RegistrationFormData
{
    /**
     * @var string|null
     *
     * @Assert\NotNull()
     */
    private $username;

    /**
     * @var string|null
     *
     * @Assert\NotNull()
     * @Assert\Email()
     */
    private $email;

    /**
     * @var string|null
     *
     * @Assert\NotNull()
     */
    private $password;

    /**
     * @var string|null
     *
     * @Assert\IdenticalTo(propertyPath="password", message="password_confirm.no_match")
     */
    private $passwordConfirm;

    /**
     * @return null|string
     */
    public function getUsername (): ?string
    {
        return $this->username;
    }

    /**
     * @param null|string $username
     * @return RegistrationFormData
     */
    public function setUsername (?string $username): RegistrationFormData
    {
        $this->username = $username;
        return $this;
    }

    /**
     * @return null|string
     */
    public function getEmail (): ?string
    {
        return $this->email;
    }

    /**
     * @param null|string $email
     * @return RegistrationFormData
     */
    public function setEmail (?string $email): RegistrationFormData
    {
        $this->email = $email;
        return $this;
    }

    /**
     * @return null|string
     */
    public function getPassword (): ?string
    {
        return $this->password;
    }

    /**
     * @param null|string $password
     * @return RegistrationFormData
     */
    public function setPassword (?string $password): RegistrationFormData
    {
        $this->password = $password;
        return $this;
    }

    /**
     * @return null|string
     */
    public function getPasswordConfirm (): ?string
    {
        return $this->passwordConfirm;
    }

    /**
     * @param null|string $passwordConfirm
     * @return RegistrationFormData
     */
    public function setPasswordConfirm (?string $passwordConfirm): RegistrationFormData
    {
        $this->passwordConfirm = $passwordConfirm;
        return $this;
    }
}

UniqueDto.php

<?php
declare(strict_types=1);

namespace App\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\Exception\ConstraintDefinitionException;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

/**
 * @Annotation
 * @Target({"CLASS", "ANNOTATION"})
 */
class UniqueDto extends Constraint
{
    public $message = 'This value is already used.';

    /**
     * @var string|null
     */
    public $em = null;

    /**
     * @var string
     */
    public $entityClass;

    /**
     * @var array
     */
    public $fields;

    /**
     * @var string|null
     */
    public $errorPath = null;

    /**
     * @var string|null
     */
    public $entityField = null;

    /**
     * @var array|null
     */
    public $idFields = null;

    //public $ignoreNull = true; // TODO

    public function __construct ($options = null)
    {
        parent::__construct($options);

        if (!is_array($this->fields)) {
            throw new UnexpectedTypeException($this->fields, 'array');
        }

        if (!is_string($this->entityClass)) {
            throw new UnexpectedTypeException($this->entityClass, 'string');
        }

        if ($this->errorPath !== null && !is_string($this->errorPath)) {
            throw new UnexpectedTypeException($this->errorPath, 'string or null');
        }

        if (count($this->fields) < 1) {
            throw new ConstraintDefinitionException('Please specify at least one field to check');
        }

        if ($this->entityField !== null && $this->idFields !== null) {
            throw new ConstraintDefinitionException('Cannot define both entityField and idFields');
        }

        if ($this->entityField !== null && !is_string($this->entityField)) {
            throw new UnexpectedTypeException($this->entityField, 'string or null');
        }

        if ($this->idFields !== null && !is_array($this->idFields)) {
            throw new UnexpectedTypeException($this->fields, 'array or null');
        }

        if ($this->idFields !== null && count($this->idFields) < 1) {
            throw new ConstraintDefinitionException('Please specify at least one id field to check');
        }
    }

    public function getRequiredOptions ()
    {
        return ['entityClass', 'fields'];
    }

    public function getTargets()
    {
        return self::CLASS_CONSTRAINT;
    }
}

UniqueDtoValidator.php

<?php
declare(strict_types=1);

namespace App\Validator\Constraints;

use Closure;
use Doctrine\Common\Collections\Criteria;
use Doctrine\Common\Collections\Expr\Comparison;
use Doctrine\Common\Collections\Expr\Value;
use Doctrine\Common\Collections\Selectable;
use Doctrine\Common\Persistence\ManagerRegistry;
use Doctrine\Common\Persistence\ObjectManager;
use Symfony\Component\PropertyAccess\PropertyAccessorInterface;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\ConstraintDefinitionException;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

class UniqueDtoValidator extends ConstraintValidator
{
    /**
     * @var ManagerRegistry
     */
    private $doctrine;

    /**
     * @var PropertyAccessorInterface
     */
    private $propertyAccessor;

    /**
     * @var Closure
     */
    private $privatePropertyAccessor;

    /**
     * @var bool
     */
    private $debugFailures;

    public function __construct (
        ManagerRegistry $doctrine,
        PropertyAccessorInterface $propertyAccessor,
        bool $debugFailures
    ) {
        $this->doctrine = $doctrine;
        $this->propertyAccessor = $propertyAccessor;
        $this->debugFailures = $debugFailures;
    }

    public function validate ($object, Constraint $constraint)
    {
        if (!$constraint instanceof UniqueDto) {
            throw new UnexpectedTypeException($constraint, __NAMESPACE__ . '\UniqueDto');
        }

        $this->privatePropertyAccessor = Closure::bind(
            function (string $property) {
                return $this->{$property};
            },
            $object,
            get_class($object)
        );

        $fields = $this->normalizeFields($constraint->fields);
        $values = $this->getFieldValues($fields, $object);
        $criteria = $this->addComparisonsToCriteria(
            Criteria::create(),
            $this->buildComparisons($fields, $values)
        );

        $idFields = null;

        if ($constraint->entityField !== null) {
            $entity = $this->getPropertyValue($object, $constraint->entityField);

            if ($entity !== null) {
                $em = $this->getManager($constraint);
                $metadata = $em->getClassMetadata($constraint->entityClass);

                // Fake that we have properties directly in DTO
                $idFields = $this->normalizeFields($metadata->getIdentifierFieldNames());
                $idValues = $metadata->getIdentifierValues($entity);
            }
        } elseif ($constraint->idFields !== null) {
            $idFields = $this->normalizeFields($constraint->idFields);
            $idValues = $this->getFieldValues($idFields, $object);
        }

        if ($idFields !== null) {
            /** @noinspection PhpUndefinedVariableInspection */
            $idComparisons = $this->buildComparisons($idFields, $idValues, true);
            $this->addComparisonsToCriteria($criteria, $idComparisons);
        }

        $results = $this->getRepository($constraint, $em ?? null)->matching($criteria);
        $resultsCount = $results->count();

        if ($resultsCount === 0) {
            return;
        }

        $builder = $this->context->buildViolation($constraint->message);
        $errorPath = $constraint->errorPath;

        if (count($constraint->fields) === 1) {
            $value = current($values);

            if (
                !is_array($value) && !is_resource($value) &&
                (!is_object($value) || $value instanceof \DateTimeInterface || method_exists($value, '__toString'))
            ) {
                $builder->setParameter(
                    '{{ value }}',
                    $this->formatValue($value, self::PRETTY_DATE & self::OBJECT_TO_STRING)
                );
            }

            $builder->setInvalidValue($value);

            if ($errorPath === null) {
                $errorPath = key($values);
            }
        }

        if ($this->debugFailures) {
            $builder->setCause($resultsCount === 1 ? $results[0] : $results->toArray());
        }

        $builder
            ->atPath($errorPath)
            ->addViolation();
    }

    private function getPropertyValue ($object, $property)
    {
        if ($this->propertyAccessor->isReadable($object, $property)) {
            return $this->propertyAccessor->getValue($object, $property);
        } else {
            $accessor = $this->privatePropertyAccessor;
            return $accessor($property);
        }
    }

    private function getRepository (UniqueDto $constraint, ?ObjectManager $manager = null): Selectable
    {
        if ($manager === null) {
            $manager = $this->getManager($constraint);
        }

        $repository = $manager->getRepository($constraint->entityClass);

        if (!$repository instanceof Selectable) {
            throw new \LogicException(sprintf(
                '%s does not implement %s which is required for UniqueDto validation',
                get_class($repository), Selectable::class
            ));
        }

        return $repository;
    }

    private function getManager (UniqueDto $constraint): ObjectManager
    {
        if ($constraint->em !== null) {
            return $this->doctrine->getManager($constraint->em);
        }

        $em = $this->doctrine->getManagerForClass($constraint->entityClass);

        if ($em === null) {
            throw new ConstraintDefinitionException(sprintf(
                'Class "%s" is not managed by doctrine',
                $constraint->entityClass
            ));
        }

        return $em;
    }

    private function normalizeFields (array $initial): array
    {
        $normalized = [];

        foreach ($initial as $dtoProperty => $entityProperty) {
            if (is_numeric($dtoProperty)) {
                $dtoProperty = $entityProperty;
            }

            $normalized[$dtoProperty] = $entityProperty;
        }

        return $normalized;
    }

    private function getFieldValues (array $fields, $object): array
    {
        $values = [];

        foreach ($fields as $dtoProperty => $entityProperty) {
            $values[$dtoProperty] = $this->getPropertyValue($object, $dtoProperty);
        }

        return $values;
    }

    private function buildComparisons (array $fields, array $values, bool $negate = false): array
    {
        $comparisons = [];

        foreach ($fields as $dtoProperty => $entityProperty) {
            $operation = $negate ? Comparison::NEQ : Comparison::EQ;
            $comparisons[] = new Comparison($entityProperty, $operation, new Value($values[$dtoProperty]));
        }

        return $comparisons;
    }

    private function addComparisonsToCriteria (Criteria $criteria, array $comparisons): Criteria
    {
        if (count($comparisons) === 1) {
            $criteria->andWhere($comparisons[0]);
        } else {
            $criteria->andWhere(Criteria::expr()->andX(...$comparisons));
        }

        return $criteria;
    }
}

Hello, you have saved me, I have been looking for a way to implement unique validations using Dto's for some time, thanks for sharing your code, the implementation I had made did not meet all the use cases and this one did.

It would be nice if you showed the DTO configuration to implement this validation.

@allfreelancers a little late I think but maybe someone else will give you some light on how to implement it, I did the following:

inside my validations folder I have a deviceDto.yml file with the following:

App\Form\Model\DeviceDto:
constraints:
-App\Validator\UniqueCustomTestConstraint:
fields: ['deviceIdentifier']
entityClass: App\Entity\Device
idFields: [id]
properties:
deviceIdentifier:
-NotNull:
groups: [Default]
-NotBlank:
groups: [Default]