Eloquent - Having problems using eager loading on nested relationships - php

Question

I'm trying to eager load nested relationships, but I'm having trouble returning the correct results.
Here are the models:
User.php
class User extends Model
{
public function universities()
{
return $this->hasMany('\StudentApp\Models\UserUniversity');
}
}
UserUniversity.php
class UserUniversity extends Model
{
protected $fillable = [ 'user_id', 'university_id', 'choice' ];
public function university()
{
return $this->hasOne('\StudentApp\Models\University');
}
}
University.php
class University extends Model
{
protected $table = 'university';
}
What I want to do is get a user by ID, fetch the users universities from the UserUniversity pivot table, and then fetch the name of that university from the University table.
I've tried the following to test if it works:
$user = User::with('universities')->find($this->jwtObject->uid);
return $response->withJson($user->universities[0]->university);
But I get the following error:
Column not found: 1054 Unknown column 'university.user_university_id' in 'where clause' (SQL: select * from `university` where `university`.`user_university_id` = 10 and `university`.`user_university_id` is not null limit 1) [] {"uid":"28c5a97"}
user.user_university_id is incorrect. That column doesn't exist and I'm not sure why it's trying to use that column.
What it should be using is user.university_id
How can I do this?

Answer 1

You should add foreign key and primary key in relation:
public function universities()
{
return $this->hasMany('\StudentApp\Models\University', 'university_id', 'id');
}

Answer 2

Correct nested eager loading syntax is:
User::with('universities.university')
Also, make sure you've using the correct foreign key in the university table:
user_university_id
Or define another key in the relationship:
public function university()
{
return $this->hasOne('\StudentApp\Models\University', 'another_foreign_key');
}