fix primary key mapping for the entity in the model

Author: michalsn

system/Model.php

@@ -592,9 +592,9 @@ protected function doErrors()
      */
     public function getIdValue($row)
     {
-        if (is_object($row) && isset($row->{$this->primaryKey})) {
+        if (is_object($row)) {
             // Get the raw primary key value of the Entity.
-            if ($row instanceof Entity) {
+            if ($row instanceof Entity && $row->{$this->primaryKey} !== null) {
                 $cast = $row->cast();
 
                 // Disable Entity casting, because raw primary key value is needed for database.
@@ -608,7 +608,9 @@ public function getIdValue($row)
                 return $primaryKey;
             }
 
-            return $row->{$this->primaryKey};
+            if (! $row instanceof Entity && isset($row->{$this->primaryKey})) {
+                return $row->{$this->primaryKey};
+            }
         }
 
         if (is_array($row) && isset($row[$this->primaryKey])) {

tests/system/Models/SaveModelTest.php

@@ -365,4 +365,44 @@ public function testUseAutoIncrementSetToFalseSaveObject(): void
         $this->assertSame($insert['key'], $this->model->getInsertID());
         $this->seeInDatabase('without_auto_increment', $update);
     }
+
+    /**
+     * @see https://github.com/codeigniter4/CodeIgniter4/issues/9306
+     */
+    public function testSaveNewEntityWithMappedPrimaryKey(): void
+    {
+        $entity = new class () extends Entity {
+            protected $name;
+            protected $attributes = [
+                'id'   => null,
+                'name' => null,
+            ];
+            protected $original = [
+                'id'   => null,
+                'name' => null,
+            ];
+            protected $datamap = [
+                'new_kid_in_the_block' => 'id',
+            ];
+        };
+
+        $testModel = new class () extends Model {
+            protected $table         = 'empty';
+            protected $allowedFields = [
+                'name',
+            ];
+            protected $returnType = 'object';
+        };
+
+        $entity->name = 'New';
+        $this->assertTrue($testModel->save($entity));
+        $this->seeInDatabase('empty', ['id' => 1, 'name' => 'New']);
+
+        $entity->new_kid_in_the_block = 1;
+        $entity->name                 = 'Updated';
+        $this->assertTrue($testModel->save($entity));
+
+        $this->seeInDatabase('empty', ['id' => 1, 'name' => 'Updated']);
+        $testModel->truncate();
+    }
 }

user_guide_src/source/changelogs/v4.5.6.rst

@@ -38,10 +38,10 @@ Bugs Fixed
 - **DownloadResponse:** Fixed a bug that prevented setting custom cache headers. We can now also use the ``setCache()`` method.
 - **DownloadResponse:** Fixed a bug involving sending a custom "Expires-Disposition" header.
 - **Routing:** Fixed a TypeError in `str_replace()` when `Routing::$translateURIDashes` is set to `true` and a route is defined using a closure.
-
 - **Validation:** Fixed a bug where complex language strings were not properly handled.
 - **CURLRequest:** Added support for handling proxy responses using HTTP versions other than 1.1.
 - **Database:** Fixed a bug that caused ``Postgre\Connection::reconnect()`` method to throw an error when the connection had not yet been established.
+- **Model** Fixed a bug that caused the ``Model::getIdValue()`` method to not correctly recognize the primary key in the ``Entity`` object if a data mapping for the primary key was used.
 
 See the repo's
 `CHANGELOG.md <https://github.com/codeigniter4/CodeIgniter4/blob/develop/CHANGELOG.md>`_