凌乱的雄辩连接查询 - Laravel 4, messy Eloquent join query

我正在做一个乱七八糟的项目，其中数据库的结构是:

Object
id, title, description, url ... [and some more columns]
ObjectMeta
object_id, variable, value

那么我们给你:

Object: 1, 'Cool Book', 'This cool book is just for you!', ...
Object Meta:
1, 'author_name', 'John Doe'
1, 'released', 2014
1, 'price', 23.22
1, 'url', 'http://amazon.com/coolbook'
1, 'genre', 3

所以我需要执行查询，它将:

拉出所有类型为3的对象，然后按发布日期对这些对象进行排序。

$objs = static::Active()
->where('object', '=', $object)
->where('category','=',$category)
->whereIn('site_id', array(self::$site_id, 0))
->leftJoin('object_meta', function($join)
{
  $join->on('object.id','=', 'object_meta.content_id');
})
->where('object_meta.variable', 'genre')
->where('object_meta.value', 3);
->where('object_meta.variable', 'released');
->orderBy('object_meta.value', 'desc');
->groupBy('object.id')
->paginate(20);

这个查询有0个结果，即使那里有很多这样的书。我知道第二个object_meta。变量where在这里是有罪的。我怎么写这个查询使它工作?

非常感谢你的帮助。

——编辑

我已经创建了一个解决方案，但它是非常非常糟糕的解决方案(有趣的是，我发誓上面的查询工作了一个月左右)。

$objs = static::Active()
->where('object', '=', $object)
->where('category','=',$category)
->whereIn('site_id', array(self::$site_id, 0))
->leftJoin('object_meta', function($join)
{
  $join->on('object.id','=', 'object_meta.content_id');
})
->where('object_meta.variable', 'genre')
->where('object_meta.value', 3);
->groupBy('object.id')
->get();
foreach($objs as $obj)
{
  $obj->id = $obj->object_id;
    $objs_meta = ObjectMeta::where('object_id',$obj->object_id)->get();
    foreach($objs_meta as $obj_meta)
    {
      $variable = $obj_meta->var;
      $obj->$variable = $obj_meta->value;
    }
}
$objs = $objs->sortBy(function($role){
  return $role->released;
});
$objs = Paginator::make($objs->toArray(), sizeof($objs), $limit);

您需要内连接(join())而不是leftJoin()，并且您需要两次:

$objs = static::Active()
 ->where('object', '=', $object)
 ->where('category','=',$category)
 ->whereIn('site_id', array(self::$site_id, 0))
 ->join('object_meta as genre', function ($join) {
   $join->on('object.id', '=', 'genre.content_id')
      ->where('genre.variable', '=', 'genre')
      ->where('genre.value', '=', 3);
 })
 ->join('object_meta as released', function ($join) {
   $join->on('object.id', '=', 'released.content_id')
      ->where('released.variable', '=', 'released');
 })
 ->orderBy('released.value', 'desc');
 ->select('object.*', 'released.value as released')
 ->distinct()
 // or group by, doesn't matter in your case
 // ->groupBy('object.id')
 ->paginate(20);

那么你的对象将有额外的属性released与适当的值。

根据注释:

如果你想动态添加连接，那么我建议像下面这样的作用域:

public function scopeGenre($query, $value)
{
   $query->join('object_meta as genre', function ($join) use ($value) {
       $join->on('object.id', '=', 'genre.content_id')
          ->where('genre.variable', '=', 'genre')
          ->where('genre.value', '=', $value);
     });
}

$query->where(..)->genre(3)->...