feature #38662 [DoctrineBridge][Validator] Allow validating every class against unique entity constraint (wkania)

This PR was merged into the 7.1 branch.

Discussion
----------

[DoctrineBridge][Validator] Allow validating every class against unique entity constraint

| Q             | A
| ------------- | ---
| Branch?       | 7.x <!-- see below -->
| Bug fix?      | no
| New feature?  | yes <!-- pleasedate src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #22592
| License       | MIT
| Doc PR        | symfony/symfony-docs#14458 <!-- required for new features -->

Yet another try to allow validating every class against unique entity constraint.
Based on the knowledge from issue symfony/symfony#22592 and pull request symfony/symfony#24974.

This constraint doesn’t provide any protection against race conditions, which is enough in most cases. You can always try-catch flush method. Let's not talk about this problem.

Current state:
- can be applied only to an entity,
- support entity inheritance,
- can validate unique combinations of multiple fields,
- meaningful errors related to entities,
- is valid during an update, when the only matched entity is the same as the entity being validated

New state:
- preserve the current state,
- all old tests pass (no changes in them),
- no breaking changes,
- can be applied to any class (like DTO),
- can map object fields to entity fields (optional),
- when the object update some entity, there is an option to provide the identifier field names to match that entity (optional)

Examples:
1. DTO adds a new entity.
```
namespace App\Message;

use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;

/**
 * `@UniqueEntity`(fields={"name"}, entityClass="App\Entity\User")
 */
class HireAnEmployee
{
    public $name;

    public function __construct($name)
    {
        $this->name = $name;
    }
}
```

2. DTO adds a new entity, but the name of the field in the entity is different.
```
namespace App\Message;

use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;

/**
 * `@UniqueEntity`(fields={"name": "username"}, entityClass="App\Entity\User")
 */
class HireAnEmployee
{
    public $name;

    public function __construct($name)
    {
        $this->name = $name;
    }
}
```

3. DTO updates an entity.
```
namespace App\Message;

use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;

/**
 * `@UniqueEntity`(fields={"name"}, entityClass="App\Entity\User", identifierFieldNames={"uid": "id"})
 */
class UpdateEmployeeProfile
{
    public $uid;
    public $name;

    public function __construct($uid, $name)
    {
        $this->uid = $uid;
        $this->name = $name;
    }
}
```

Commits
-------

adb9afa4a5 [DoctrineBridge][Validator] Allow validating every class against unique entity constraint

Author: fabpot

CHANGELOG.md

@@ -7,6 +7,7 @@ CHANGELOG
  * Deprecate the `DoctrineExtractor::getTypes()` method, use `DoctrineExtractor::getType()` instead
  * Allow `EntityValueResolver` to return a list of entities
  * Add support for auto-closing idle connections
+ * Allow validating every class against `UniqueEntity` constraint
 
 7.0
 ---

Tests/Fixtures/CreateDoubleNameEntity.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class CreateDoubleNameEntity
+{
+    public $primaryName;
+    public $secondaryName;
+
+    public function __construct($primaryName, $secondaryName)
+    {
+        $this->primaryName = $primaryName;
+        $this->secondaryName = $secondaryName;
+    }
+}

Tests/Fixtures/Dto.php

@@ -0,0 +1,17 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class Dto
+{
+    public string $foo;
+}

Tests/Fixtures/HireAnEmployee.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class HireAnEmployee
+{
+    public $name;
+
+    public function __construct($name)
+    {
+        $this->name = $name;
+    }
+}

Tests/Fixtures/UpdateCompositeIntIdEntity.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class UpdateCompositeIntIdEntity
+{
+    public $id1;
+    public $id2;
+    public $name;
+
+    public function __construct($id1, $id2, $name)
+    {
+        $this->id1 = $id1;
+        $this->id2 = $id2;
+        $this->name = $name;
+    }
+}

Tests/Fixtures/UpdateCompositeObjectNoToStringIdEntity.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class UpdateCompositeObjectNoToStringIdEntity
+{
+    /**
+     * @var SingleIntIdNoToStringEntity
+     */
+    protected $object1;
+
+    /**
+     * @var SingleIntIdNoToStringEntity
+     */
+    protected $object2;
+
+    public $name;
+
+    public function __construct(SingleIntIdNoToStringEntity $object1, SingleIntIdNoToStringEntity $object2, $name)
+    {
+        $this->object1 = $object1;
+        $this->object2 = $object2;
+        $this->name = $name;
+    }
+
+    public function getObject1(): SingleIntIdNoToStringEntity
+    {
+        return $this->object1;
+    }
+
+    public function getObject2(): SingleIntIdNoToStringEntity
+    {
+        return $this->object2;
+    }
+}

Tests/Fixtures/UpdateEmployeeProfile.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bridge\Doctrine\Tests\Fixtures;
+
+class UpdateEmployeeProfile
+{
+    public $id;
+    public $name;
+
+    public function __construct($id, $name)
+    {
+        $this->id = $id;
+        $this->name = $name;
+    }
+}