code: public function actionCreate()
      {
          $model = new Post();
          $model->time = date("Y-m-d H:i:s");	
          $model->author_id = Yii::$app->user->id;
          $model->isdel = 0;
  
          if (Yii::$app->request->post())        
          {
  			$post = Yii::$app->request->post();									
  			$category = [];						
  			if (isset($post['Post']['category']))
  			{
  				$category = $post['Post']['category'];
  			}		
  			
  			if (is_array($post['Post']['tags']))
  			{
  				$post['Post']['tags'] = implode(",",$post['Post']['tags']);
  			}		
  				
  			$model->load($post);
  			
  			$transaction = Yii::$app->db->beginTransaction();
  			try {				
  				
  				if ($model->save()) {
  					
  					$cs = BlogCatPos::deleteAll("post_id = :id",["id"=>$model->id]);
  					
  					foreach ($category as $d)
  					{
  						$c = new BlogCatPos();						
  						$c->post_id = $model->id;
  						$c->category_id = $d;
  						$c->isdel = 0;					
  						$c->save();								
  					}
  									
  					$transaction->commit();                                    				
  					return $this->redirect(['view', 'id' => $model->id]);            
  				}				
  				else
  				{
  					$model->id = array_merge($category,[]);	
  					$transaction->rollBack();					
  				}				
  			} catch (Exception $e) {
  				$transaction->rollBack();				
  			}   						
  		}	
          
          return $this->render('create', [
  			'model' => $model,
  		]);
      }
docs: Creates a new Post model.
  If creation is successful, the browser will be redirected to the 'view' page.
  @return mixed