[置顶] 让我爱恨的ThinkPHP Relation

     还记得第一次用ThinkPHP的relation,做了一个关联查询，觉得特别好用。有那么一天尝试着用关联插入，怎么插，都插不进，我插，我擦！

     后来在龙哥的指点下算是成功的实践了一次，后来怎么用都不顺，后来变远离了 relation,便觉得这是TP 本身的问题，却不知是自己没有找到问题的症结，还是编程届

的那句谚语说的好，你没有了解出现问题的真正原因，就不算解决了BUG。

     最近公司做接口，两张表一对多的关系， 正常查询的话（select tag.*, evaluate.* from tbl_tag as tag,tbl_evaluate as evaluate where(tag.tag_id = evaluate.tag_id)）是多条记录，而需要返回如下的JSON数据：

{
    "ret": "0",
    "msg": "ok",
    "data": [
         {
            "tag_id": "1226",
            "name": "软件故障类",
            "type": "1",
            "Icon": "/style/images/sortImgs/small/",
            "created_at": "1373383665",
            "status": "1",
            "explain": "暂无",
            "changed_at": "1373383665",
            "evaluate_count": "5",
            "contents_type": "1",
            "process_id": null,
            "evaluate": [
                {
                    "evaluate_id": "4",
                    "tag_id": "1226",
                    "name": "任务创建时间",
                    "limit_time": "0",
                    "alert_time": "0",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                },
                {
                    "evaluate_id": "5",
                    "tag_id": "1226",
                    "name": "任务分配时间",
                    "limit_time": "10",
                    "alert_time": "5",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                },
                {
                    "evaluate_id": "6",
                    "tag_id": "1226",
                    "name": "任务领取时间",
                    "limit_time": "15",
                    "alert_time": "3",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                },
                {
                    "evaluate_id": "7",
                    "tag_id": "1226",
                    "name": "任务开始时间",
                    "limit_time": "60",
                    "alert_time": "20",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                },
                {
                    "evaluate_id": "8",
                    "tag_id": "1226",
                    "name": "任务结束时间",
                    "limit_time": "240",
                    "alert_time": "30",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                }
            ]
        },
        {
            "tag_id": "1229",
            "name": "改进后的任务我22",
            "type": "1",
            "Icon": "/style/images/sortImgs/small/",
            "created_at": "1373700085",
            "status": "1",
            "explain": null,
            "changed_at": "1373700979",
            "evaluate_count": "5",
            "contents_type": "1",
            "process_id": null,
            "evaluate": [
                {
                    "evaluate_id": "10",
                    "tag_id": "1229",
                    "name": "时间1",
                    "limit_time": "11",
                    "alert_time": "6",
                    "position": "1",
                    "description": null,
                    "isfixed": null,
                    "status": null,
                    "remark": null
                }
            ]
        },
        {
            "tag_id": "1230",
            "name": "维修任务修改2",
            "type": "1",
            "Icon": "/style/images/sortImgs/small/",
            "created_at": "1373714061",
            "status": "1",
            "explain": null,
            "changed_at": "1373715337",
            "evaluate_count": "2",
            "contents_type": "1",
            "process_id": null,
            "evaluate": [
                {
                    "evaluate_id": "11",
                    "tag_id": "1230",
                    "name": "执行时间1",
                    "limit_time": "4",
                    "alert_time": "3",
                    "position": "1",
                    "description": null,
                    "isfixed": "1",
                    "status": "1",
                    "remark": null
                },
                {
                    "evaluate_id": "12",
                    "tag_id": "1230",
                    "name": "执行时间1",
                    "limit_time": "5",
                    "alert_time": "4",
                    "position": "2",
                    "description": null,
                    "isfixed": "1",
                    "status": "1",
                    "remark": null
                }
            ]
        }
   ]
}

阅读别人的代码的时候，发现TP的  relation能返回这样的数据，好了，躲不掉的Relation

马上我就又凌乱了，之前的TP直接继承RelationModel,关联查询  so  easy, 关键是公司继承了BaseModel,各种研究，各种陌生

/**
 * 通过id查询标签
 */

public function show(){
	
		//自动校验
		$dr_tag=D('Tag');
		$condition=$dr_tag->create($_GET);
		if( false === $condition) exit(RS::jsonReturn($dr_tag->getError()));
	
		$dr_process = D('Process');
		$dr_process = $dr_process->switchModel ( 'Relation' );
		$linklist = ProcessModel::get_link ( 'this' );
		$dr_process->setProperty ( '_link', $linklist );
	
		$field = TagModel::getObjFields ( 'this' );
	
		$tags_id=$condition['tags_id'];
		$name=$condition['name'];
		$explain=$condition['explain'];
		if(empty($tags_id) && empty($name) && empty($explain)) exit(RS::jsonReturn("20001"));
	
		//查询条件
		if (!empty ( $tags_id)) $where ['tbl_tag.tag_id'] = array ('eq', $condition['tags_id'] );
		if (!empty ( $condition ['name'] )) $where ['tbl_tag.name'] = array ('eq', $name );
		if (!empty ( $condition ['explain'] )) $where ['tbl_tag.explain'] = array ('like','%'.$explain.'%');
		$where['tbl_tag.tag_id'][]=array('neq',999);
		$field[] = 'tbl_tag.tag_id';
		$field[] = 'tbl_tag.name';
		$field[] = 'tbl_tag.type';
		$field[] = 'tbl_tag.status';
		$field[] = 'tbl_tag.Icon';
		$field[] = 'tbl_tag.created_at';
		$field[] = 'tbl_tag.changed_at';
		$field[] = 'tbl_tag.explain';
		$field[] = 'tbl_tag.contents_type';
		$field[] = 'tbl_tag.process_id';
		$field[] = 'tbl_process.process_count';
		
		$data = $dr_process->field ( $field )
		->join ( 'right join tbl_tag ON tbl_tag.process_id = tbl_process.process_id' )
		->where ( $where )
		->relation ( true )
		->find();
	
		//返回数据
		if(empty($data)) exit(RS::jsonReturn("20000"));
		echo RS::jsonReturn("0",$data,"ok");
	
	}

照猫画虎，自己来一个，尽管搞不明白：

$linklist = ProcessModel::get_link ( 'this' );
$dr_process->setProperty ( '_link', $linklist );

//关联,显示所有任务类型和指标详情
protected function tagsShow_link(){
return array(
'evaluate'=>array(
'mapping_type' => HAS_MANY,
'class_name'=>'Evaluate',
'foreign_key'=>'tag_id',
//'mapping_name' =>'indexs',
'mapping_fields_name' =>'this'
),
);

}

/* 返回字段 */
public static function tagsShowObjFields(){
$ObjFields = self::$allObjFields;
foreach ($ObjFields as $key=>$val){
if('notifications_enabled' === $val) unset($ObjFields[$key]);
}
return $ObjFields;
}

结果就是出不来结果，Relation不出来，出来的就是关联的是false  

源于不明白这个get_link和  setProperty总是以为是这里出了批漏，各种查，各种对比，各种纠结，一个人，在周六

$linklist = ProcessModel::get_link ( 'this' );
$dr_process->setProperty ( '_link', $linklist );

找到了一条靠谱的解决方法，是改RelationModel下面的M 方法为D （ http://lhdeyx.blog.163.com/blog/static/318196972010112351516763/），我打开一看，晕死了，就是D；

之前都是在物理上实现外键约束的，现在是在逻辑上实现，以为Relation关联不上错在这里，实际上是无关的

无奈了，最后，想SQL语句，一开始就想到了，下面的，觉得可行，就是效率太低，PASS

$tag = D('Tag');
		$evaluate = D('Evaluate');
		$tag_ids = $tag->getField('tag_id,name');
		if(isset($_GET['since_at']) && !empty($_GET['since_at'])){
			$since_at = $_GET['since_at'];
			$condition['changed_at'] = array('gt',$since_at);
		}
		//echo $tag->getLastSQl();die();
		foreach($tag_ids as $key=>$val){
			$map['tag_id'] = array('eq',$key);
			$condition['tag_id'] = array('eq',$key);
			$result = $tag->where($condition)->find();
			$res = $evaluate->where($map)->select();
			$result['indexs'] = $res;
			$data[] = $result;
		}
		//返回数据
		if(empty($data)) exit(RS::jsonReturn("20000"));
		echo RS::jsonReturn("0",$data,"ok");

后来就google大神，论坛，以至于差点用起了行列转换

--行列转换模型
select name 姓名,
max(case subject when '语文' then result else 0 end) 语文,
max(case subject when '数学' then result else 0 end) 数学,
max(case subject when '物理' then result else 0 end) 物理
from tb
group by name

纠结在继续，

在sql搞不定之后，回到了Relation,还是搞不定，夜很静了，我只能简单粗暴了，一开始的sql.

…………

方姐，来了，观察了一下情况，该有的都有了，于是

$data = $dr_tag->relation(true)->select();
$evaluate = D('Evaluate');
 echo $evaluate->getLastSql();die('dd');

我一下就反映过来了，告诉TA是limit_time,后来改了Model中的字段

sudo rm -rf  *,TA迷人的样子让我折服，轻轻的在我耳边说，该了Model要删缓存，Ta 说的那么轻描淡写，我觉永远记住了

我之前也

echo $dr_tag->getLastSql();die('dd');提示的错误让人更纠结。回想Ta 解决BUG缜密思路，我…………

提示你false, 我永远都不知道用被关联的表evaluate实例化后输出，直到Ta 展示给我

爱上了Relation,  爱上……