Use primary key instead of binding key in case of BelongsToMany association

src/Listener/RelatedModelsListener.php

@@ -6,6 +6,7 @@
 use Cake\Datasource\EntityInterface;
 use Cake\Event\EventInterface;
 use Cake\ORM\Association;
+use Cake\ORM\Association\BelongsToMany;
 use Cake\Utility\Inflector;
 use RuntimeException;
 
@@ -118,6 +119,12 @@ public function publishRelatedModels(?string $action = null, ?EntityInterface $e
      */
     protected function _findOptions(Association $association): array
     {
+        if ($association instanceof BelongsToMany) {
+            return [
+                'keyField' => $association->getPrimaryKey(),
+            ];
+        }
+
         return [
             'keyField' => $association->getBindingKey(),
         ];

tests/Fixture/BlogsFixture.php

@@ -10,14 +10,15 @@ class BlogsFixture extends TestFixture
         'is_active' => ['type' => 'boolean', 'default' => true, 'null' => false],
         'name' => ['type' => 'string', 'length' => 255, 'null' => false],
         'body' => ['type' => 'text', 'null' => false],
+        'user_id' => ['type' => 'uuid', 'null' => false],
         '_constraints' => ['primary' => ['type' => 'primary', 'columns' => ['id']]],
     ];
 
     public $records = [
-        ['name' => '1st post', 'body' => '1st post body'],
-        ['name' => '2nd post', 'body' => '2nd post body'],
-        ['name' => '3rd post', 'body' => '3rd post body'],
-        ['name' => '4th post', 'body' => '4th post body'],
-        ['name' => '5th post', 'body' => '5th post body'],
+        ['name' => '1st post', 'body' => '1st post body', 'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd'],
+        ['name' => '2nd post', 'body' => '2nd post body', 'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd'],
+        ['name' => '3rd post', 'body' => '3rd post body', 'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd'],
+        ['name' => '4th post', 'body' => '4th post body', 'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd'],
+        ['name' => '5th post', 'body' => '5th post body', 'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd'],
     ];
 }

tests/TestCase/Action/AddActionTest.php

@@ -19,7 +19,7 @@ class AddActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Table class to mock on
@@ -111,6 +111,7 @@ function ($event) {
         $this->post('/blogs/add', [
             'name' => 'Hello World',
             'body' => 'Pretty hot body',
+            'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd',
         ]);
 
         $this->assertEvents(['beforeSave', 'afterSave', 'setFlash', 'beforeRedirect']);
@@ -157,6 +158,7 @@ function ($event) {
             'name' => 'Hello World',
             'body' => 'Pretty hot body',
             '_add' => 1,
+            'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd',
         ]);
 
         $this->assertEvents(['beforeSave', 'afterSave', 'setFlash', 'beforeRedirect']);
@@ -202,6 +204,7 @@ function ($event) {
             'name' => 'Hello World',
             'body' => 'Pretty hot body',
             '_edit' => 1,
+            'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd',
         ]);
 
         $this->assertEvents(['beforeSave', 'afterSave', 'setFlash', 'beforeRedirect']);
@@ -404,6 +407,7 @@ function ($event) {
         $this->{$method}('/blogs/add.json', [
             'name' => '6th blog post',
             'body' => 'Amazing blog post',
+            'user_id' => '0acad6f2-b47e-4fc1-9086-cbc906dc45fd',
         ]);
         $this->assertTrue($this->_subject->success);
         $this->assertTrue($this->_subject->created);

tests/TestCase/Action/DeleteActionTest.php

@@ -17,7 +17,7 @@ class DeleteActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Table class to mock on

tests/TestCase/Action/EditActionTest.php

@@ -18,7 +18,7 @@ class EditActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Table class to mock on

tests/TestCase/Action/IndexActionTest.php

@@ -16,7 +16,7 @@ class IndexActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Data provider with all HTTP verbs

tests/TestCase/Action/LookupActionTest.php

@@ -16,7 +16,7 @@ class LookupActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Test with no extra options

tests/TestCase/Action/ViewActionTest.php

@@ -16,7 +16,7 @@ class ViewActionTest extends IntegrationTestCase
      *
      * @var array
      */
-    protected $fixtures = ['plugin.Crud.Blogs'];
+    protected $fixtures = ['plugin.Crud.Blogs', 'plugin.Crud.Users'];
 
     /**
      * Data provider with all HTTP verbs

tests/test_app/src/Model/Table/BlogsTable.php

@@ -10,6 +10,13 @@ class BlogsTable extends Table
 {
     public $customOptions;
 
+    public function initialize(array $config): void
+    {
+        parent::initialize($config);
+
+        $this->belongsTo('Users');
+    }
+
     /**
      * findWithCustomOptions
      *