How To Create a One To Many Relationship in Laravel 10?

Hi friends,

Today I explain how to create a one-to-many relationship in Laravel 10. so now in this tutorial, I will show you Laravel 10 one to many eloquent relationships. When one table refers to many rows in another table that is called a one-to-many relationship. A one-to-many relationship is a very basic type of database relationship in Laravel 10.

Using one-to-many relationships, you can perform crud (create, read, update, delete) operations with the eloquent model from the database table in Laravel 10.

So let's start following example:

Step 1: Download Laravel

Let us begin the tutorial by installing a new Laravel application. if you have already created the project, then skip the following step.

composer create-project laravel/laravel example-app

Step 2: Add Migrations

Now we have to create a migration of the "posts" and "comments" tables. we will also add a foreign key to the posts table. so let's create like as below:

php artisan make:migration create_posts_table

database\migrations\2014_10_12_000000_create_posts_table

<?php
  
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
  
return new class extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->string("name");
            $table->timestamps();
        });
    }
  
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('posts');
    }
};

comments table migration:

php artisan make:migration create_comments_table

database\migrations\2014_10_12_000000_create_comments_table

<?php
  
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
  
return new class extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('comments', function (Blueprint $table) {
            $table->id();
            $table->foreignId('post_id')->constrained('posts');
            $table->string("comment");
            $table->timestamps();
        });
    }
  
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('comments');
    }
};

Step 3: Add Models

Here, we will create Post and Comment table model. we will also use "hasMany()" and "belongsTo()" for relationship of both model.

php artisan make:model Post

app/Models/Post.php

<?php
  
namespace App\Models;
  
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
  
class Post extends Model
{
    use HasFactory;
 
    /**
     * Get the comments for the blog post.
     *   
     * Syntax: return $this->hasMany(Comment::class, 'foreign_key', 'local_key');
     *
     * Example: return $this->hasMany(Comment::class, 'post_id', 'id');
     * 
     */
    public function comments()
    {
        return $this->hasMany(Comment::class);
    }
}

Comment Model:

php artisan make:model Comment

app/Models/Comment.php

<?php
  
namespace App\Models;
  
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
  
class Comment extends Model
{
    use HasFactory;
  
    /**
     * Get the post that owns the comment.
     *  
     * Syntax: return $this->belongsTo(Post::class, 'foreign_key', 'owner_key');
     *
     * Example: return $this->belongsTo(Post::class, 'post_id', 'id');
     * 
     */
    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

Step 4: Retrieve Records:

php artisan make:controller PostController

app/Http/Controllers/PostController.php

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\Post;
  
class PostController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $comments = Post::find(1)->comments;
  
        dd($comments);
    }
}

app/Http/Controllers/PostController.php

<?php
 
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\Comment;
  
class PostController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $post = Comment::find(1)->post;
  
        dd($post);
    }
}

Step 5: Add Records:

app/Http/Controllers/PostController.php

<?php
  
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\Post;
use App\Models\Comment;
  
class PostController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $post = Post::find(1);
   
        $comment = new Comment;
        $comment->comment = "Hi ItSolutionStuff.com";
           
        $post = $post->comments()->save($comment);
    }
}

app/Http/Controllers/PostController.php

<?php
  
namespace App\Http\Controllers;
   
use Illuminate\Http\Request;
use App\Models\Post;
use App\Models\Comment;
  
class PostController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $post = Post::find(1);
   
        $comment1 = new Comment;
        $comment1->comment = "Hi ItSolutionStuff.com Comment 1";
           
        $comment2 = new Comment;
        $comment2->comment = "Hi ItSolutionStuff.com Comment 2";
           
        $post = $post->comments()->saveMany([$comment1, $comment2]);
    }
}

app/Http/Controllers/PostController.php

<?php
   
namespace App\Http\Controllers;
  
use Illuminate\Http\Request;
use App\Models\Post;
use App\Models\Comment;
  
class PostController extends Controller
{
    /**
     * Write code on Method
     *
     * @return response()
     */
    public function index(Request $request)
    {
        $comment = Comment::find(1);
        $post = Post::find(2);
           
        $comment->post()->associate($post)->save();
    }
}

I hope it will help you..