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Laravel Many-to-Many Relationship with Example

August 18, 2024   Laravel

Maintaining relationships between instances in a Laravel network is an important part of database management. Many-to-many relationships are especially useful when more than one entry in one table is linked to multiple accounts in any other table. In this guide we will cover what Laravel multi-multi-courting is and how to implement it using a concrete example:

1. What is Laravel Relationship Many and Many?

Laravel allows for more to more scheduling when a file in one table can be linked to more than one article in any other table, and vice versa, for example: scholars can list two mentors and many students can register in one way. This time frame is generally used in situations where various factors are closely related.

2. Establishing many-to-many relationships in Laravel

To define a many-to-many relationship in Laravel, you need to fashion and create a pivot desk that connects the two tables. Recall the Student and Learning models.

First, create styles and their corresponding migrations:

php artisan make:model Student -m
php artisan make:model Course -m

Next, create a migration for the pivot table that links students to courses:

php artisan make:migration create_course_student_table --create=course_student

In the migration file for the pivot table:

Schema::create('course_student', function (Blueprint $table) {
    $table->id();
    $table->unsignedBigInteger('student_id');
    $table->unsignedBigInteger('course_id');
    $table->timestamps();

    $table->foreign('student_id')->references('id')->on('students')->onDelete('cascade');
    $table->foreign('course_id')->references('id')->on('courses')->onDelete('cascade');
});

php artisan migrate

use App\Models\Course;

class Student extends Model
{
    public function courses()
    {
        return $this->belongsToMany(Course::class);
    }
}

use App\Models\Student;

class Course extends Model
{
    public function students()
    {
        return $this->belongsToMany(Student::class);
    }
}

$student = Student::find(1);
$student->courses()->attach(2); // Attach course with ID 2 to student with ID 1

$student->courses()->detach(2); // Detach course with ID 2 from student with ID 1

$student->courses()->sync([1, 2, 3]); // Sync courses with IDs 1, 2, 3 for the student

$student = Student::find(1);
$courses = $student->courses;

$students = Student::with('courses')->get();