Laravel 4，凌乱的口才连接查询

Question

I'm working on somehow messy project where structure of db is:

Object
id, title, description, url ... [and some more columns]

ObjectMeta
object_id, variable, value

So let's give you:

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

So I need to perform query which will:

Pull all Objects that has genre 3, then sort those Objects by their released date.

$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);

This query has 0 results even if there are plenty of those books out there. I know that the second object_meta.variable where is guilty here. How can I write this query to make it work?

Really appreciating your help.

-- Edit

I've created workaround but it's really, really bad workaround (funny thing is that I swear the query above was working for month or so).

$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);

Answer 1

You need inner join ( join() ) not leftJoin() , and you need it twice:

$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);

Then your objects will have additional property released with appropriate value.

---

According to the comments:

If you want to dynamically add the joins, then I suggest scopes like below:

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);
     });
}

then:

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