How to make composite/multiple primary key in Laravel >= 5.6? - php

Question

I have a many-to-many relationship created between USERS and COURSES. The models and migrations are made as follows.
User Model:
public function courses()
{
return $this->belongsToMany(Course::class)->withTimestamps();
}
Course Model:
public function users()
{
return $this->belongsToMany(User::class, 'course_user', 'course_id', 'user_id')->withTimeStamps();
}
The problem is I cannot find a way to implement a composite primary key into my migration file or pivot table in Laravel like this,
Schema::create('course_user', function (Blueprint $table) {
$table->increments('id');
$table->timestamps();
$table->integer('course_id')->unsigned()->index()->primary();
$table->foreign('course_id')->references('id')->on('courses');
$table->integer('user_id')->unsigned()->index()->primary();
$table->foreign('user_id')->references('id')->on('users');
});
After coding the above, when I call php artisan migrate:refresh an error appears showing multiple primary keys performed in the linked table. So I did a research on this matter and found out that ELOQUENT does not support composite primary keys as stated in this forum: link to the forum
Is there any other way I can go around this?
I have somehow managed to write a piece of code to detect a existing entries in the pivot table or the many-to-many relationship, inside the controller and avoid new duplicate entries.

Answer 1

To counter attack this problem I wrote a piece code in the controller to detect an existing tuple in the pivot table as follows. NOTE: I have used Resources to retrieve data, you can avoid the Resource functions and use the normal method also.
The userId and courseId are passed as parameters in the request:
public function index(Request $request) {
$target = new AcademicPaymentResource(User::with('courses')->findOrFail($request['userId']));
if ($target != null)
{
foreach ($target as $query){
// search for existing tuples
foreach ($query->courses as $subQuery => $key){
// Check if courseId in existing tuple is equal to the courseId of request
if ( $query->courses[$subQuery]->pivot->course_id == $request['courseId']){
// Do anything here..
// display data to test if it works
return $query->courses[$subQuery];
}
}
// update the pivot table if the tuple doesnt exist
$user = User::findOrFail($request['userId']);
$user->courses()->attach($request['courseId']);
// read tuple data again to display if it works
$target = new AcademicPaymentResource(User::with('courses')->findOrFail($request['userId']));
return $target;
}
}
}
This method actually works fine, since I have used it flawlessly so far.
But if there is any other proper method please don't hesitate to answer..