CDataProvider,顾名思义,数据提供者,它提供了三个抽象方法(fetchData,、fetchKeys 和 calculateTotalItemCount),分别为调用不同数据结构的数据提供了获取数据、获取键值、获取数量的,接口,在YII框架中,CActiveDataProvider、CArrayDataProvider、CSqlDataProvider是它的子类,除了提供数据之外,他还提供分页和排序功能。下面以获取数据fetchData()为例
CActiveDataProvider通过CActiveRecord的子类和CDbCriteria对象
/** * Fetches the data from the persistent data storage. * @return array list of data items */ protected function fetchData() { $criteria=clone $this->getCriteria(); if(($pagination=$this->getPagination())!==false) { $pagination->setItemCount($this->getTotalItemCount()); $pagination->applyLimit($criteria); } $baseCriteria=$this->model->getDbCriteria(false); if(($sort=$this->getSort())!==false) { // set model criteria so that CSort can use its table alias setting if($baseCriteria!==null) { $c=clone $baseCriteria; $c->mergeWith($criteria); $this->model->setDbCriteria($c); } else $this->model->setDbCriteria($criteria); $sort->applyOrder($criteria); } $this->model->setDbCriteria($baseCriteria!==null ? clone $baseCriteria : null); $data=$this->model->findAll($criteria); $this->model->setDbCriteria($baseCriteria); // restore original criteria return $data; }CArrayDataProvider通过传人的原生数据来获取数据
/** * Fetches the data from the persistent data storage. * @return array list of data items */ protected function fetchData() { if(($sort=$this->getSort())!==false && ($order=$sort->getOrderBy())!='') $this->sortData($this->getSortDirections($order)); if(($pagination=$this->getPagination())!==false) { $pagination->setItemCount($this->getTotalItemCount()); return array_slice($this->rawData, $pagination->getOffset(), $pagination->getLimit()); } else return $this->rawData; }CSqlDataProvider通过传人的sql,经过db执行获取数据
/** * Fetches the data from the persistent data storage. * @return array list of data items */ protected function fetchData() { $sql=$this->sql; $db=$this->db===null ? Yii::app()->db : $this->db; $db->active=true; if(($sort=$this->getSort())!==false) { $order=$sort->getOrderBy(); if(!empty($order)) { if(preg_match('/\s+order\s+by\s+[\w\s,]+$/i',$sql)) $sql.=', '.$order; else $sql.=' ORDER BY '.$order; } } if(($pagination=$this->getPagination())!==false) { $pagination->setItemCount($this->getTotalItemCount()); $limit=$pagination->getLimit(); $offset=$pagination->getOffset(); $sql=$db->getCommandBuilder()->applyLimit($sql,$limit,$offset); } $command=$db->createCommand($sql); foreach($this->params as $name=>$value) $command->bindValue($name,$value); return $command->queryAll(); }