Laravel 10 One to Many Eloquent Relationship Tutorial

Laravel 10 One to Many Eloquent Relationship Tutorial

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Inside this article we will see the concept i.e Eloquent one-to-many relationship in Laravel 10 Tutorial. Article contains the classified information i.e What is One to Many Relationship and How it works in laravel.

We will see the complete Idea of Best practices for using one-to-many relationships in Laravel 10.

In Laravel, One-to-Many Eloquent Relationship is a type of database relationship in which one model is associated with multiple instances of another model. In this type of relationship, a single record from one table (parent model) has many related records in another table (child model).

For this tutorial we will consider a posts table and a comments table. This means a single post can have multiple comments.

Learn More –

Let’s get started.

Laravel Installation

Open terminal and run this command to create a laravel project.

$ composer create-project laravel/laravel myblog

It will create a project folder with name myblog inside your local system.

To start the development server of laravel – 

$ php artisan serve

URL: http://127.0.0.1:8000

Assuming laravel already installed inside your system.

Create Database & Connect

To create a database, either we can create via Manual tool of PhpMyadmin or by means of a mysql command.

CREATE DATABASE laravel_app;

To connect database with application, Open .env file from application root. Search for DB_ and update your details.

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=laravel_app
DB_USERNAME=root
DB_PASSWORD=root

Create Migrations

We need to create two migration files.

  • Migration file for Posts table
  • Migration file for Comments table

Open project terminal and run these migrations command.

$ php artisan make:migration CreatePostsTable

$ php artisan make:migration CreateCommentsTable

It will create two files 2023_03_06_150722_create_posts_table.php & 2023_03_06_150840_create_comments_table.php inside /database/migrations folder.

Open xxx_create_posts_table.php and write this complete code into it.

<?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("title");
            $table->text("description")->nullable();
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('posts');
    }
};

Next,

Open xxx_create_comments_table.php and write this code into it.

<?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');
    }
};

Run Migrations

Next, we need to migrate migrations.

$ php artisan migrate

This command will create tables inside database.

Create Model & Add Relationships

Next,

We need to create two models. Back to project terminal and run these artisan commands.

$ php artisan make:model Post

$ php artisan make:model Comment

This command will create two files Post.php & Comment.php inside /app/Models folder.

Open Post.php and write this complete code into it.

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\HasMany;
use App\Models\Comment;

class Post extends Model
{
    use HasFactory;

    protected $fillable = [
        "title", 
        "description"
    ];

    /**
     * Get the comments for the blog post.
     */
    public function comments(): HasMany
    {
        return $this->hasMany(Comment::class);
    }
}

$this->hasMany(Comment::class); This means that one Post can have many comments. This is establishing One-To-Many Relationship.

Usage

$comments = Post::find(1)->comments;

Inverse Relationship One-To-Many

Open Comment.php model file and write this complete code into it.

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use App\Models\Post;

class Comment extends Model
{
    use HasFactory;

    protected $fillable = [
        "post_id",
        "comment"
    ];

    /**
     * Get the post that owns the comment.
     */
    public function post(): BelongsTo
    {
        return $this->belongsTo(Post::class);
    }
}

$this->belongsTo(Post::class); This means a comment has a associated post with it. This is establishing Inverse of One-To-Many Relationship.

Usage

$comment = Comment::find(1);

Controller Usage

Now, let’s test with a dummy application controller file.

Open any controller say DataController.php file from /app/Http/Controllers folder.

Here, we have created two methods in which we use model methods as a property.

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Models\Post;
use App\Models\Comment;

class DataController extends Controller
{
    public function getComments($post_id)
    {
        // Passing post id into find()
        return Post::find($post_id)->comments;
    }

    public function getPost($comment_id)
    {
        // Passing comment id into find()
        return Comment::find($comment_id);
    }
}

Few details,

  • Post::find($post_id)->comments; It will find comments detail values by post id. One to Many
  • Comment::find($comment_id)->post; It will find post detail by comment id. Inverse of One to Many / Belongs To

Add Routes

Open web.php from /routes folder and add these routes into it.

//...

use App\Http\Controllers\DataController;

Route::get('get-comments/{id}', [DataController::class, 'getComments']);
Route::get('get-post/{id}', [DataController::class, 'getPost']);

//...

Application Testing

Open project to terminal and type the command to start development server 

$ php artisan serve

URLs

Get Comments – http://127.0.0.1:8000/get-comments/1

Get Post detail– http://127.0.0.1:8000/get-post/1

We hope this article helped you to learn Laravel 10 One to Many Eloquent Relationship Tutorial in a very detailed way.

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