Allow afterFind() to fully remove an associated record.

By returnning array() or unsetting the 0'th result an afterFind
callback should be able to fully remove data from the results.

Fixes #3541

lib/Cake/Model/Datasource/DboSource.php

@@ -1153,10 +1153,12 @@ class DboSource extends DataSource {
 			}
 			$linkedModel = $model->{$className};
 			$filtering[] = $className;
-			foreach ($results as &$result) {
+			foreach ($results as $key => &$result) {
 				$data = $linkedModel->afterFind(array(array($className => $result[$className])), false);
 				if (isset($data[0][$className])) {
 					$result[$className] = $data[0][$className];
+				} else {
+					unset($results[$key]);
 				}
 			}
 		}

lib/Cake/Test/Case/Model/ModelReadTest.php

@@ -3007,6 +3007,30 @@ class ModelReadTest extends BaseModelTest {
 	}
 
 /**
+ * Test that afterFind can completely unset data.
+ *
+ * @return void
+ */
+	public function testAfterFindUnset() {
+		$this->loadFixtures('Article', 'Comment', 'User');
+		$model = new CustomArticle();
+		$model->bindModel(array(
+			'hasMany' => array(
+				'ModifiedComment' => array(
+					'className' => 'ModifiedComment',
+					'foreignKey' => 'article_id',
+				)
+			)
+		));
+		$model->ModifiedComment->remove = true;
+		$result = $model->find('all');
+		$this->assertTrue(
+			empty($result[0]['ModifiedComment']),
+			'Zeroith row should be removed by afterFind'
+		);
+	}
+
+/**
  * testFindThreadedNoParent method
  *
  * @return void

lib/Cake/Test/Case/Model/models.php

@@ -552,6 +552,13 @@ class ModifiedComment extends CakeTestModel {
 	public $useTable = 'comments';
 
 /**
+ * Property used to toggle filtering of results
+ *
+ * @var boolean
+ */
+	public $remove = false;
+
+/**
  * belongsTo property
  *
  * @var array
@@ -567,6 +574,9 @@ class ModifiedComment extends CakeTestModel {
 		if (isset($results[0])) {
 			$results[0]['Comment']['callback'] = 'Fire';
 		}
+		if ($this->remove) {
+			return array();
+		}
 		return $results;
 	}