Eager loading relationship returns empty using SELECT in WITH clause - laravel

Question

Using Laravel 5.4, I have a query that correctly returns a relationship. Using the "with" clause in the query, I am attempting to return only selected columns from the relationship in my controller.
When I add the select to the with clause, relationship returns an empty array. Oddly enough, if I add a different parameter, such as a groupBy or join the query DOES return results. So something about my setup dislikes the select on the query.
Thus far I have tried:
using selectRaw
using select(DB::raw)
tried defining this as a separate relationship on my model.
Nothing has worked this far. Sql log looks good when I dump it.
Here is my model:
// MODEL
namespace App;
use Illuminate\Database\Eloquent\Model;
use DB;
class ClassBlocks extends Model
{
public $timestamps = false;
public function schedule(){
return $this->hasMany('App\ClassSchedules', 'class_block_id', 'id');
}
}
And here is my controller:
//CONTROLLER
use App;
use DateTime;
use Illuminate\Http\Request;
class ProgramsController extends Controller
{
public function filterClass(Request $request, App\ClassBlocks $block)
{
$block = $block->newQuery();
// Attempt to eager load relationship
// Returns results when "select" disabled
$block->with([
'schedule' => function($query){
$query->select('time_start');
$query->groupBy('day');
},
]);
return $block->get();
}
}
Here is a sample result with select enabled (schedule returns empty):
[
{
"id": 13,
"program_id": "1",
"class_group_id": "1",
"schedule": [
]
}
]
And here is a result with select disabled (returns relationship when select disabled):
[
{
"id": 13,
"program_id": "1",
"class_group_id": "1",
"schedule": [
{
"id": 338,
"class_group_id": "1",
"program_id": "1",
"class_block_id": "13",
"date": "06/13/2017",
"day": "Tuesday",
"instructor_id": "1",
"time_start": "6:30am",
"time_end": "6:30am"
},
{
"id": 339,
"class_group_id": "1",
"program_id": "1",
"class_block_id": "13",
"date": "06/14/2017",
"day": "Wednesday",
"instructor_id": "2",
"time_start": "6:30am",
"time_end": "6:30am"
}
]
},
]
Any insight would be greatly appreciated.

Answer 1

The problem here is:
$query->select('time_start');
Laravel need to have column that is connection between 2 records. In this case you should probably use:
$query->select('time_start', 'class_block_id');
to make it work.
Obviously you will have class_block_id in response this way. If you really don't want it, probably you should create some transformer that will return exactly you want in response.