How to Join Three Tables in Laravel Using Eloquent Relationships?

Joining Three Tables Using Laravel Eloquent Model

Introduction

In Laravel, retrieving relational data is simplified with Eloquent models. This article demonstrates how to join three tables using Eloquent to retrieve data from the Articles, Categories, and Users tables.

Database Schema

Consider the following database schema:

Articles Table	Categories Table	User Table
id	id	id
title	category_name	user_name
body		user_type
categories_id
user_id

Objective

The goal is to retrieve articles along with their corresponding category name instead of the category_id, and user name instead of the user_id.

Eloquent Implementation

Define the relationships between the models based on the database schema:

Article.php:

namespace App\Models;

use Eloquent;

class Article extends Eloquent
{
    protected $table = 'articles';

    public function user()
    {
        return $this->belongsTo('App\Models\User');
    }

    public function category()
    {
        return $this->belongsTo('App\Models\Category');
    }
}

Category.php:

namespace App\Models;

use Eloquent;

class Category extends Eloquent
{
    protected $table = "categories";

    public function articles()
    {
        return $this->hasMany('App\Models\Article');
    }
}

User.php:

namespace App\Models;

use Eloquent;

class User extends Eloquent
{
    protected $table = 'users';

    public function articles()
    {
        return $this->hasMany('App\Models\Article');
    }
}

Data Retrieval

To retrieve articles with related data:

$articles = \App\Models\Article::with(['user','category'])->get();

Usage

Access the related data as follows:

// Retrieve user name
$article->user->user_name

// Retrieve category name
$article->category->category_name

Retrieval with Specific Relations

To retrieve articles within a category or by a specific user:

$categories = \App\Models\Category::with('articles')->get();
$users = \App\Models\Category::with('users')->get();

Conclusion

Laravel's Eloquent models greatly simplify the task of retrieving relational data. By understanding the relationships between models and setting them up in your code, you can easily access the necessary data and perform more complex queries efficiently.

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