Add Pagination to relationship and get the relationship's relationship - Laravel - php

Question

I am building a forum website using Laravel and Vue.
I have three tables: forums, posts, and users.
One forum can have multiple posts, each post has a user who created the post.
When the user clicks on one forum, I want to display the latest 10 posts to this forum with the paginate method.
Forum.php
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class Forum extends Model {
use HasFactory;
protected $table = 'forums';
protected $guarded = [];
/**
* Get the forum posts
* #return \Illuminate\Database\Eloquent\Relations\HasMany
*/
public function posts() {
return $this->hasMany(Post::class)->orderBy('created_at', 'DESC');
}
}
Post.php
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class Post extends Model {
use HasFactory;
protected $table = 'posts';
protected $guarded = [];
/**
* Get the post's user
* #return \Illuminate\Database\Eloquent\Relations\BelongsTo
*/
public function user() {
return $this->belongsTo(User::class);
}
}
User.php
<?php
namespace App\Models;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
class User extends Authenticatable {
use HasFactory, Notifiable;
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password',
'remember_token',
];
/**
* The attributes that should be cast to native types.
*
* #var array
*/
protected $casts = [
'email_verified_at' => 'datetime',
];
/**
* Get the user posts
* #return \Illuminate\Database\Eloquent\Relations\HasMany
*/
public function posts() {
return $this->hasMany(Post::class);
}
}
Here I retrieve the forum posts with the users.
ForumService.php
<?php
namespace App\Services;
use App\Models\Forum;
class ForumService {
public static function getForumPosts($forumId) {
$forum = Forum::with('posts.user')->find($forumId);
dd($forum);
}
}
However, I want to retrieve only 10 posts and get each post's user, so how do I do that in a relationship? The posts are paginated, but how to I get now the posting user? Because the dot syntax is applying to the user, therefore I paginate the user, not the posts.
ForumService.php
<?php
namespace App\Services;
use App\Models\Forum;
class ForumService {
public static function getForumPosts($forumId) {
$forum = Forum::with(
[
'posts' => function ($query) { // How do I get the post user?
return $query->paginate(10);
}
]
)->find($forumId);
dd($forum);
}
}

Answer 1

Just add the with method inside the query scope of the function you have created.
$forum = Forum::with(
[
'posts' => function ($query) {
// returns posts with user
return $query->with('user')->paginate(10);
}
]
)->find($forumId);
Now you can access the first user with $forum->posts[0]->user which will not query to the database but will prefetch the users and populate it in paginator collection.

Answer 2

As you have already the id of the forum you can only retrieve posts which belongs to that Forum and paginate them like this
public static function getForumPosts($forumId) {
return Forum::find($forumId)->posts()->paginate(10);
}
If you want to eager load Post creator you can perform that like this
public static function getForumPosts($forumId) {
return Forum::find($forumId)->posts()->with(['user'])->paginate(10);
}