Sorting by eloquent relationship in Laravel using DataTables - php

Question

I'm trying to use DataTables to display list of Application model.
Application model has operations:
public function operations(){
return $this->hasMany('\App\Operation', 'application_id', 'id');
}
Operations model has state:
public function state(){
return $this->belongsTo('App\State', 'status_id', 'id');
}
and operation author (user):
public function user(){
return $this->hasOne('App\User', 'id', 'user_id');
}
To enable datatable i'm using this code:
$(function() {
$('#applications-table').DataTable({
language: {
"url": "/js/Polish.json"
},
processing: true,
serverSide: true,
ajax: '{!! route('applications.data') !!}',
columns: [
{ data: 'number', name: 'number', className: "vertical_middle", searchable: true},
{ data: 'operations.0.correspondence', name: 'operations.correspondence', className: "vertical_middle", orderable: false, searchable: false},
{ data: 'operations.0.comment', name: 'operations.comment', className: "vertical_middle", orderable: false, searchable: true},
{ data: 'operations.0.prognosed', name: 'operations.prognosed', className: "vertical_middle", searchable: false},
{ data: 'operations.0.state.name', name: 'operations.state.name', className: "vertical_middle", searchable: false},
{ data: 'operations.0.created_at', name: 'operations.created_at', className: "vertical_middle", type: "date", searchable: true},
]
});
});
ApplicationController is serving data using this code
$model = Application::with(array(
'operations' => function ($query) {
$query->orderByDesc('operations.created_at')->with('state')->with('user');
}
));
return Datatables::of($model)->make(true);
And finally a problem - table is rendering properly, but when I try to sort by another column than the first one I receive warning:
DataTables warning: table id=applications-table - Requested unknown parameter 'operations.0.correspondence' for row 0.
Honestly, I have no idea how to make it work.
Thank you in advance.

Answer 1

Fixed by using DB::table
$applications = DB::table('applications as a')
->join('operations as o', function($join){
$join->on('o.application_id', '=', 'a.id')
->on('o.id', '=', DB::raw("(SELECT max(id) from operations WHERE operations.application_id = a.id)"));
})
->join('users as u', 'o.user_id', '=', 'u.id')
->join('states as s', 'o.status_id', '=', 's.id')
->select(['a.id as a_id','a.number','o.*', 'u.name as u_name', 'u.surname as u_surname', 's.name as s_name']);
return Datatables::of($applications)->make(true);