Level 24
Hi @zakaria_tbey ,
Thanks for posting. Could you simplify it by adding a university_id to your students table?
It would simplify your query and I feel you would use this relation in many areas of your app.
Jun 27, 2020
5
Level 1
Laravel Nova BelongsTo field display nested relationship
Hello Guys,
I've been struggling with this problem for the last 48 hours
I would like to add a BelongsTo field to display Universities Drop-down in a Student Resource
Here's my models : Student -> Section -> Course -> Departement -> University
class Student extends Model
{
public function section()
{
return $this->belongsTo('App\Section');
}
}
class Section extends Model
{
public function courses()
{
return $this->belongsTo('App\Course');
}
}
class Course extends Model
{
public function departement()
{
return $this->belongsTo('App\Departement');
}
}
class Departement extends Model
{
public function university()
{
return $this->belongsTo('App\University');
}
}
I was thinking about something like this :
class Student extends Model
{
public function university()
{
return $this->section->courses->departement->university;
}
}
But it doesn't really work
Any solution to properly solve this issue ?
staudenmeir/belongs-to-through package may works but not in my case because i have custom local keys and this package doesn't support custom local keys
Level 1
Hey @richardbishopme ,
Thanks for your reply
I'll need this kind of relationship in many models
I'm using Nova Ajax Select package to load related models
the Admin choose first an University
then he'll choose one of the sections which belongs to the selected university
then he'll choose one of the departments which belongs to the selected university
then he'll choose one of the courses which belongs to the selected department
then he'll choose one of the sections which belongs to the selected course
therefore adding a university_id to the student table is not a solution for me because I'll also need to add department_id and course_id
I believe there's a way to get nested belongsto relationship in laravel, there's a missing piece which i could not figure it out
Level 24
Hi @zakaria_tbey ,
No probs :) In this bit of your code:
class Section extends Model
{
public function courses()
{
return $this->belongsTo('App\Course');
}
}
Should courses by just course?
class Section extends Model
{
public function course()
{
return $this->belongsTo('App\Course');
}
}
Then following this relation should work:
class Student extends Model
{
public function university()
{
return $this->section->course->departement->university;
}
}
Note course not courses
Level 1
Hey @richardbishopme ,
It's note a course or courses problem because this is just an example and returning $this->section->course->department->university doesn't return a relationship object therefore it doesn't serve the cause in Nova
But I've found a work around for this using Eloquent Mutators to trick the Student model that i have an university_id attribute in my student table
Here's my work around for anyone who face the same issue
I'm only using Traits to make the code clean & reusable
<?php
namespace App\Traits;
trait BelongsToUniversity
{
public function initializeAppendAttributeTrait()
{
$this->append('university_id');
}
public function university()
{
return $this->belongsTo('App\University');
}
public function getUniversityIdAttribute()
{
if(empty($this->section)
|| empty($this->section->course)
|| empty($this->section->course->department)
|| empty($this->section->course->department->university)
){
return null;
}
$item = $this->section->course->department->university->toArray();
return isset($item['id']) ? $item['id'] : null;
}
public function setUniversityIdAttribute($attr)
{
$this->university_id = $attr;
}
}
<?php
class Student extends Model
{
use \App\Traits\BelongsToUniversity;
....
Now you can get a belongsTo university relationship by simply calling (new Student())->university()
Level 24
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