[TASK] Typed vs Untyped properties in Extbase (#5532)

* [TASK] Typed vs Untyped properties in Extbase

Releases: main, 13.4, 12.4

* [TASK] Typed vs Untyped properties in Extbase

Releases: main, 13.4, 12.4

* Apply suggestions from code review

Co-authored-by: Stefan Bürk <[email protected]>

---------

Co-authored-by: Stefan Bürk <[email protected]>

Author: linawolf

Documentation/ExtensionArchitecture/Extbase/Reference/Domain/Model/Index.rst

@@ -94,6 +94,38 @@ however get displayed when explicitly called:
     But it is there:
     <f:debug>{post.info.combinedString}</f:debug>
 
+..  _extbase-model-properties-untyped:
+
+Typed vs. untyped properties in Extbase models
+==============================================
+
+In Extbase, you can define model properties using either PHP native type
+declarations or traditional `@var` annotations. Typed properties are
+preferred, untyped properties are still supported for backward compatibility.
+
+The example below demonstrates a basic model with both a typed and an untyped
+property:
+
+..  literalinclude:: _codesnippets/_untypedProperties.php
+    :caption: EXT:my_extension/Classes/Domain/Model/Blog.php
+
+-   `$title` is a *typed property*, using PHP’s type declaration. This is the
+    recommended approach as it enforces type safety and improves code
+    readability.
+
+-   `$published` is an *untyped property*, defined only with a docblock. This
+    remains valid and is often used in older codebases.
+
+For persisted properties (those stored in the database), ensure that the
+property type matches the corresponding
+`TCA Field type <https://docs.typo3.org/permalink/t3tca:columns-types>`_
+to avoid data mapping errors.
+
+Nullable and `Union types <https://docs.typo3.org/permalink/t3coreapi:extbase-model-properties-union-types>`_
+are also supported.
+
+..  note:: Typed properties are strongly encouraged in all new TYPO3 extensions.
+
 ..  _extbase-model-properties-default-values:
 
 Default values for model properties

Documentation/ExtensionArchitecture/Extbase/Reference/Domain/Model/_codesnippets/_untypedProperties.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Vendor\Extension\Domain\Model;
+
+use TYPO3\CMS\Extbase\DomainObject\AbstractEntity;
+
+class Blog extends AbstractEntity
+{
+    /**
+     * Typed property (preferred)
+     *
+     * @var string
+     */
+    protected string $title = '';
+
+    /**
+     * Untyped property (legacy-compatible)
+     *
+     * @var bool
+     */
+    protected $published = false;
+
+    // Getters and Setters
+}