How to Use hasManyThrough in Eloquent Laravel

In Laravel Eloquent, use hasManyThrough to define a relationship that accesses distant related models through an intermediate model. It allows you to retrieve records from a final model by going through a middle model, like getting all posts for a country through users. Define it in the parent model with hasManyThrough(FinalModel::class, IntermediateModel::class).

Syntax

The hasManyThrough method defines a relationship from a parent model to a distant model through an intermediate model.

• FinalModel::class: The model you want to access.
• IntermediateModel::class: The model that connects the parent and final models.
• Optional keys can be passed to specify foreign and local keys if they don't follow conventions.

php

public function finalModels()
{
    return $this->hasManyThrough(FinalModel::class, IntermediateModel::class,
        'foreign_key_on_intermediate', // Foreign key on intermediate model
        'foreign_key_on_final',        // Foreign key on final model
        'local_key_on_parent',         // Local key on parent model
        'local_key_on_intermediate'    // Local key on intermediate model
    );
}

Example

This example shows how to get all Posts for a Country through Users. Each country has many users, and each user has many posts.

php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Country extends Model
{
    public function posts()
    {
        return $this->hasManyThrough(Post::class, User::class);
    }
}

class User extends Model
{
    public function posts()
    {
        return $this->hasMany(Post::class);
    }
}

class Post extends Model
{
    // Post belongs to User
    public function user()
    {
        return $this->belongsTo(User::class);
    }
}

// Usage example:
$country = Country::find(1);
$posts = $country->posts; // Gets all posts from users in this country

foreach ($posts as $post) {
    echo $post->title . "\n";
}

Output

Post titles printed line by line for all posts by users in country with ID 1

Common Pitfalls

• Not matching foreign and local keys correctly causes empty results.
• Assuming default key names when your database uses different column names.
• Using hasManyThrough when a direct hasMany or belongsToMany is more appropriate.

Always verify your database keys and specify them explicitly if needed.

php

<?php
// Wrong: missing keys when table columns differ
public function posts()
{
    return $this->hasManyThrough(Post::class, User::class);
}

// Right: specify keys explicitly
public function posts()
{
    return $this->hasManyThrough(
        Post::class,
        User::class,
        'country_id', // Foreign key on users table
        'user_id',    // Foreign key on posts table
        'id',         // Local key on countries table
        'id'          // Local key on users table
    );
}

Quick Reference

Parameter	Description
FinalModel::class	The model you want to access through the intermediate model.
IntermediateModel::class	The model that connects the parent and final models.
foreign_key_on_intermediate	Foreign key on the intermediate model linking to the parent model.
foreign_key_on_final	Foreign key on the final model linking to the intermediate model.
local_key_on_parent	Primary key on the parent model.
local_key_on_intermediate	Primary key on the intermediate model.

Key Takeaways

Use hasManyThrough to access distant related models through an intermediate model in Laravel Eloquent.

Always verify and specify foreign and local keys if your database columns don't follow Laravel conventions.

hasManyThrough is ideal for relationships like Country -> Users -> Posts to get all posts for a country.

Avoid hasManyThrough if a direct relationship or belongsToMany fits better.

Test your relationship queries to ensure they return expected results.