How to use eager loading for related models in Laravel - php

Question

I have the following models:
Appointment [ belongsTo Timeslot | belongsTo User ]
Timeslot [ hasMany Appointment ]
User [ hasOne Appointment | HasOne Details ]
Details [ belongsTo User ]
I am trying to eager load the Details data starting from the Appointment model ( Appointment has a user, which has a Details record) using the following query:
$apps = Appointment::with('timeslot')->with('user')->with('user.details')->get();
This throws the following error in Builder.php
Call to a member function addEagerConstraints() on a non-object
Why am I calling on a non-object here and why is my query not working?
EDIT:
This is the relation on my User model:
public function details() {
dd($this->role_id);
switch($this->role_id) {
case 3:
return $this->hasOne('App\CandidateDetails', 'user_id');
break;
case 2:
return $this->hasOne('App\EmployerDetails', 'user_id');
break;
}
}
i'm aware that this would be better implemented using a pivot table, it's been a learning process. the dd() returns a null when called by my query, yet it works fine in other calls. What's going on here?

Answer 1

Make sure you have return in all your relation methods. It seems that one of them is not returning a Relation definition.
You can't use $this in relation definitions - attributes of the model will be uninitiated when query is built, so $this->role_id will give null and no relation will be returned.
In order to make it work you should define 2 separate relations:
// User.php
public function candidateDetails() {
return $this->hasOne('App\CandidateDetails', 'user_id');
}
public function cemployerDetails() {
return $this->hasOne('App\EmployerDetails', 'user_id');
}
public function getDetailsAttribute() {
switch($this->role_id) {
case 3:
return $this->candidateDetails;
case 2:
return $this->employerDetails;
}
}
// ...and then...
$user = User::with('candidateDetails', 'employerDetails')->findOrFail($userId);
// depending on user's role you'll get either candidate or employer details here
$details = $user->details;