Laravel pivot with multiple columns - laravel

Question

Hi I have a problem with Laravel`s pivot table.
I have the following tables: students, courses and lessons.
The table lessons is connected with courses through a foreign key courses_id, and the tables students and courses are connected through a pivot courses_students.
So I can access the information through students like this:
//Students model
public function courses()
{
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->with('lessons');
}
//Courses model
public function lessons()
{
return $this->hasMany(Lesson::class);
}
This works completely fine for this kind of relationship, but I want to add a third column in the pivot with name lesson_id for the lessons table.
I am doing this because, sometimes I need to get a specific set of lessons from each course for each user.
I succeeded in doing so, by using a model courseStudent for the pivot table.
Using the model for pivot my calls became like this.
Student->with('courseStudent.courses')
->with('courseStudent.lessons')
->get();
This partially does what I need it to do, but I want to maintain the relation ship between courses and students.
Is there a way to achieve that?

Answer 1

Example from docs(go through Many To Many):
return $this->belongsToMany('App\Role')->withPivot('column1', 'column2');
Pivot table is meant to use belongsToMany relationship on both entities.
So your students and courses should have it defined if you want pivot table between that is using eloquent default capacity.
As a side note pay attention on naming convention because that way you will reduce issues on minimum: pivot table should be tableanamesingular_tablebnamesingular where order is set by alphabetical order of tables' names (i.e. post_user Yes, user_post No).
Id fields in pivot table should be tablenamesingular_id.
You can set names however you want but this way you will have less unepected behavior in future using eloquent. All of this you have in documentation page and I recommend you go through it thoroughly.
Other way is to use dynamic properties for getting certain values. Example from docs:
$user = App\User::find(1);
foreach ($user->roles as $role) {
echo $role->pivot->created_at;
}
If you would like to manually change values in pivot table, you should create separate model for it that would be connected with that entity/table (pay attention that pivot model extends Pivot as in example from docs rather than Model):
<?php
namespace App;
use Illuminate\Database\Eloquent\Relations\Pivot;
class PostUser extends Pivot
{
// other definitions related
}

Answer 2

You can use join for third relation:
public function courses(){
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->withPivot('lesson_id')
->join('lessons','lesson_id','=','lessons.id')
->select('lessons.id','lessons.title', ...);
}

Answer 3

If you are going to use the same pivot table for courses and lessons, you can to do something like this:
//Students model
public function courses()
{
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->whereNotNull('course_id');
}
public function lessons()
{
return $this->belongsToMany(Lessons::class,'courses_students','student_id', 'lesson_id')
->whereNotNull('lesson_id');
}
Then just use it:
$courses = $student->courses;
$lessons = $student->lessons;