Has-many-through in Laravel - Mini Project: Build & Apply

Building a Has-Many-Through Relationship in Laravel

📖 Scenario: You are creating a simple Laravel app to manage countries, their users, and the posts those users write.Each Country has many Users, and each User has many Posts.You want to get all posts written by users from a specific country using Laravel's hasManyThrough relationship.

🎯 Goal: Build a Laravel model relationship using hasManyThrough so you can access all posts of a country through its users.

📋 What You'll Learn

Create a Country model with a hasManyThrough relationship to Post

Create User and Post models with correct foreign keys

Use exact method and variable names as instructed

Follow Laravel conventions for model relationships

💡 Why This Matters

🌍 Real World

This pattern is useful when you want to access related data through an intermediate model, like getting all posts from users of a country without querying users separately.

💼 Career

Understanding hasManyThrough relationships is important for Laravel developers to write clean, efficient code for complex data relations.

1

Create the initial models and database tables

Create three Laravel models: Country, User, and Post. Each model should have the following database columns:

- countries: id (primary key), name (string)
- users: id (primary key), country_id (foreign key), name (string)
- posts: id (primary key), user_id (foreign key), title (string)

Write the Eloquent model classes Country, User, and Post with the correct protected $fillable properties for name and title where applicable.

Laravel

# Create Country, User, and Post models with fillable properties
# Your code here

Need a hint?

Remember to add protected $fillable arrays in each model for mass assignment.

2

Add the hasMany relationship from Country to User

In the Country model, add a public method called users that returns a hasMany relationship to the User model using the foreign key country_id.

Laravel

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Country extends Model
{
    protected $fillable = ['name'];

    // Add the users() method here
    // Your code here
}

class User extends Model
{
    protected $fillable = ['name', 'country_id'];
}

class Post extends Model
{
    protected $fillable = ['title', 'user_id'];
}

Need a hint?

Use hasMany with the foreign key 'country_id' in the users method.

3

Add the hasManyThrough relationship from Country to Post

In the Country model, add a public method called posts that returns a hasManyThrough relationship to the Post model through the User model. Use the foreign keys country_id on User and user_id on Post.

Laravel

hasMany(User::class, 'country_id');
    }

    // Add the posts() method here
    // Your code here
}

class User extends Model
{
    protected $fillable = ['name', 'country_id'];
}

class Post extends Model
{
    protected $fillable = ['title', 'user_id'];
}

Need a hint?

Use hasManyThrough with Post::class, User::class, and the foreign keys 'country_id' and 'user_id'.

4

Use the hasManyThrough relationship in a controller

In a Laravel controller method, write code to find the Country with id 1 and get all its posts using the posts relationship. Assign the posts collection to a variable called $countryPosts.

Laravel

<?php

// In a controller method
// Your code here

Need a hint?

Use Country::find(1) to get the country, then access posts property.