How to Add Foreign Key in Laravel Migration?

his tutorial shows you how to add foreign key in laravel migration. if you want to see example of laravel migration add foreign key constraint then you are a right place. i would like to show you laravel migration create table with foreign key. you will learn create table foreign key laravel. So, let’s follow few step to create example of laravel migration create table with foreign key.

I will give you very simple example of how to create table with foreign key constraint using laravel migration. you can easily use this example with laravel 6, laravel 7, laravel 8 and laravel 9 version.

in this example, we will create “posts” and “comments” table. in comments table we will add two foreign key constraint one with posts and another with users table. so let’s simple create migration and let’s see:

Example 1:

Create Migration Command:

php artisan make:migration create_posts_table

database/migrations/2021_04_01_040458_create_posts_table.php

<?php
  
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
  
class CreatePostsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->text('body');
            $table->timestamps();
        });
  
        Schema::create('comments', function (Blueprint $table) {
            $table->id();
            $table->unsignedBigInteger('user_id');
            $table->unsignedBigInteger('post_id');
            $table->text('comment');
            $table->timestamps();
   
            $table->foreign('user_id')->references('id')->on('users');
            $table->foreign('post_id')->references('id')->on('posts');
        });
    }
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('comments');
        Schema::dropIfExists('posts');
    }
}

run migration

php artisan migrate

Output:

Example 2:

Schema::create('comments', function (Blueprint $table) {
    $table->id();
    $table->foreignId('user_id')->constrained();
    $table->foreignId('post_id')->constrained();
    $table->text('comment');
    $table->timestamps();
});

I hope it can help you…