CODEWITHSUNDEEP
laraveleloquent
Amir Sasani
Amir Sasani

Reputation: 327

How to fix laravel eloquent many to many relation insertion error on wrong table

I have a model class with the name CourseSession and it's table is course_session, and I have another model named Student and it's table is student and every session has many students and also every student could be in many sessions. So I have created a third table named student_session with student_id, session_id, presence and laravels timestamp columns.

Creating a session needs to have a list of students and I get them from $request like this: 

$validatedData = $request->validate([
    'students' => 'required',
]);

students is array of students id!

this is my CourseSession model: 

class CourseSession extends Model
{
    protected $table = 'course_sessions';
    protected $guarded = [];

    public function course()
    {
        return $this->belongsTo('App\Course');
    }

    public function students()
    {
        return $this->belongsToMany('App\Student', 'student_session','session_id', 'student_id');
    }
}

and this is my student model: 

class Student extends Model
{
    protected $guarded = [];

    public function courses()
    {
        return $this->belongsToMany('App\Course');
    }

    public function exams()
    {
        return $this->belongsToMany('App\Exam');
    }

    public function sessions()
    {
        return $this->belongsToMany('App\CourseSession', 'student_session', 'student_id', 'session_id');
    }
}

I create a session like this: 

$session = new CourseSession();
$session->course_id = $course->id;
$session->save();

and I save students this way: 

$sessions = $session->students()->create(['session_id' => $session->id, 'student_id' => 1, 'presence' => 1]);

but I get this error: 

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'session_id' in 'field list' (SQL: insert into `students` (`session_id`, `student_id`, `presence`, `updated_at`, `created_at`) values (25, 1, 1, 2019-04-28 14:24:48, 2019-04-28 14:24:48))

according to error, it tries to write data on students table but I want to write them on student_session table!

what is wrong in my codes?

Upvotes: 0

Views: 529

Answers (1)

Rwd
Rwd

Reputation: 35170

For this you want to use attach() instead of create().

$session->students()->attach(1, ['presence' => 1]);

In the above example 1 is the student_id. You don't need to specify the session_id as your calling this from a Session model. The array at the end is any additional data you want to add to the pivot table.

Since you have additional data in your student_session pivot table, it might also be an idea to add this to your belongsToMany relationships e.g.

public function sessions()
{
    return $this->belongsToMany('App\CourseSession', 'student_session', 'student_id', 'session_id')
        ->withPivot('presence')
        ->withTimestamps();
}

This will include the presence and timestamps columns in the pivot data as well (obviously, you don't have to do this if you don't want to though).

Upvotes: 1

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