Eloquent in Laravel-Datatables, select in select? - laravel

Question

I have 3 tables, the 1st has a FK from the 2nd, and the 2nd has a FK from the 3rd:
Table 1: [admin_demandas]
-------------------------
id_demanda| projec_id
-------------------------
Table 2: [admin_projec]
-------------------------
id_projec | sub_id
-------------------------
Table 3: [admin_sub]
-------------------------
id_sub | name
-------------------------
What I need is to get the 'name' from Table 3 but starting with the Model of the table 1.
I was trying something like this:
$data = AdminDemanda::select([
'id_demanda',
'admin_projec.sub_id AS sub_id',
'admin_sub.name AS name',])
->join('admin_projec', 'admin_demandas.projec_id', '=', 'admin_projec.id_projec')
->join('admin_sub', 'admin_projec.sub_id', '=', 'admin_sub.id_sub')
->get();
return Datatables::of($data)->make(true);
I've done my Datatables with only 1 JOIN (2 tables) but not sure how to do those 2 JOIN (3 tables). I got this error:
[Err] 1054 - Unknown column 'admin_projec.sub_id' in 'on clause'
What should I modify in my query?
Should I need to use query builder instead Eloquent, with a DB::raw() query?

Answer 1

Solved with this:
Inner join between three tables in mysql
it was simple... now in case anyone need it, my Datatable query is:
$datos = AdminDemanda::select([
'id_demanda',
'admin_dis.nombre AS nombre_dist',
'admin_sub.nombre AS nombre_subes',
'mes AS mes_demanda',
'admin_sistemas.nombre AS nombre_sistema',
'admin_demandas.demanda_mwh AS mwh'])
->join('admin_projec', 'admin_demandas.proyeccion_demanda_id', '=', 'admin_projec.id_proyeccion_demanda')
->join('admin_sub', 'admin_projec.subestacion_id', '=', 'admin_sub.id_subestacion')
->join('admin_dis', 'admin_projec.dist_id', '=', 'admin_dis.id_dist')
->join('admin_sistemas', 'admin_projec.sistema_id', '=', 'admin_sistemas.id_sistema')
->get();

Answer 2

You should edit your models
By exemple in AdminSub model
public function projec(){
return $this->hasMany(AdminProjec::class , 'sub_id');
}
You should be able to do
\AdminSub::first()->projec();
And continue by editing your AdminProjec model with the same kind of relationship
public function demandas(){
return $this->hasMany(AdminDemandas::class , 'projec_id');
}
And now you could try
//I do not remember which one will works
\AdminSub::first()->projec()->first()->demandas()->name
//or
\AdminSub::first()->projec()->first()->demandas()->get()->name