Making it possible to append additional links to a belongsToMany, this

assumes that joint information is present

Cake/ORM/Association/BelongsToMany.php

@@ -346,15 +346,14 @@ protected function _saveLinks(Entity $sourceEntity, $targetEntities, $options) {
 		$source = $this->source();
 		$entityClass = $pivot->entityClass();
 		$belongsTo = $pivot->association($target->alias());
-		$property = $belongsTo->property();
 		$foreignKey = (array)$this->foreignKey();
 		$assocForeignKey = (array)$belongsTo->foreignKey();
 		$targetPrimaryKey = (array)$target->primaryKey();
 		$sourcePrimaryKey = (array)$source->primaryKey();
 		$jointProperty = $target->association($pivot->alias())->property();
 
 		foreach ($targetEntities as $k => $e) {
-			$joint = $e->get($property);
+			$joint = $e->get($jointProperty);
 			if (!$joint) {
 				$joint = new $entityClass;
 				$joint->isNew(true);
@@ -372,6 +371,7 @@ protected function _saveLinks(Entity $sourceEntity, $targetEntities, $options) {
 			}
 
 			$e->set($jointProperty, $joint);
+			$e->dirty($jointProperty, false);
 		}
 
 		return true;

Cake/Test/TestCase/ORM/TableTest.php

@@ -2434,4 +2434,32 @@ public function testSaveCleanEntity() {
 		$this->assertSame($entity, $table->save($entity));
 	}
 
+/**
+ * Integration test to show how to append a new tag to an article
+ *
+ * @group save
+ * @return void
+ */
+	public function testBelongsToManyIntegration() {
+		$table = TableRegistry::get('articles');
+		$table->belongsToMany('tags');
+		$article = $table->find('all')->where(['id' => 1])->contain(['tags'])->first();
+		$tags = $article->tags;
+		$this->assertNotEmpty($tags);
+		$tags[] = new \TestApp\Model\Entity\Tag([
+			'name' => 'Something New'
+		]);
+		$article->tags = $tags;
+		$this->assertSame($article, $table->save($article));
+		$tags = $article->tags;
+		$this->assertCount(3, $tags);
+		$this->assertFalse($tags[2]->isNew());
+		$this->assertEquals(4, $tags[2]->id);
+		$this->assertEquals(1, $tags[2]->extraInfo->article_id);
+		$this->assertEquals(4, $tags[2]->extraInfo->tag_id);
+
+		$article = $table->find('all')->where(['id' => 1])->contain(['tags'])->first();
+		$this->assertEquals($tags, $article->tags);
+	}
+
 }