[Doctrine] Add documentation for Enum usage

doctrine.rst

@@ -1076,6 +1076,7 @@ Learn more
     doctrine/multiple_entity_managers
     doctrine/resolve_target_entity
     doctrine/reverse_engineering
+    doctrine/use_enum
     testing/database
 
 .. _`Doctrine`: https://www.doctrine-project.org/

doctrine/use_enum.rst

@@ -0,0 +1,43 @@
+Use Enums
+=========
+
+PHP 8.1 added native Enumerations, which can be used to define a custom type
+and its possible values. Those can be used in association with Doctrine in
+order to define a limited set of values availables for an entity property.
+
+First step is to create an enum::
+
+    // src/Enum/Suit.php
+    namespace App\Enum;
+
+    enum Suit: string {
+    case Hearts = 'H';
+    case Diamonds = 'D';
+    case Clubs = 'C';
+    case Spades = 'S';
+    }
+
+.. note::
+
+    Only backed enums can be used with properties as Doctrine use the scalar
+    equivalent of each value for storing.
+
+When the enum is created, you can use the ``enumType`` parameter of
+``#[ORM\Column]`` attribute or use it directly for a more typed property::
+
+    // src/Entity/Card.php
+    namespace App\Enum;
+
+    #[Column(type: Types::TEXT, enumType: Suit::class)]
+    public string $suit;
+
+    // or for a more typed property
+    #[Column(type: Types::TEXT)]
+    public Suit $suit;
+
+.. caution::
+
+    If you use the Symfony Maker bundle to create or update your entities,
+    there is no EnumType available. It still can be used to generate property
+    with getter and setter but you will need to update declaration according
+    to your needs.