How to limit query after with() method in laravel - php

Question

i have 2 models. PostModel and CategoriesModel.
class PostModel extends Model
{
protected $table='posts';
protected $primaryKey = 'id';
protected $guarded=['id'];
public function categories()
{
return $this->belongsTo(CategoriesModel::class);
}
}
class CategoriesModelextends Model
{
protected $table='categories';
protected $primaryKey = 'id';
protected $guarded=['id'];
public function posts()
{
return $this->hasMany(PostModel::class);
}
}
I want to get 6 categories with 10 posts.
I used this code in my controller
$categories = CategoriesModel::with(['pages' => function($query) {
$query->limit('10');
}])->take("6")->get();
but this code is wrong. it applies to all records. But the truth is that this query applies per one categories. please help me.thanks

Answer 1

there is a laravel package specialized in this called Eloquent Eager Limit:
after installing it:
composer require staudenmeir/eloquent-eager-limit:"^1.0"
you should use it inside the models that would apply limited eager loading:
class PostModel extends Model
{
use \Staudenmeir\EloquentEagerLimit\HasEagerLimit;
// ........
}
class CategoriesModel
extends Model
{
use \Staudenmeir\EloquentEagerLimit\HasEagerLimit;
// ........
}
now this query will get the result you want:
$categories = CategoriesModel::with(['pages' => function($query) {
$query->limit('10');
}])->take("6")->get();

Answer 2

For eager loading you can do like this with map operation :
$categories = CategoriesModel::with('pages')->take(6)->get()
->map(function($q)
{ $q->pages = $q->pages->take(10); // take only 10 query
return $q;
}
);
The reason the above approach is necessary is because the constrained eager loading query roughly translates to SQL like:
Query to select Categories:
select * from `categories`
limit 6;
Query to fetch relation
select * from `categories`
inner join `posts` on `categories`.`id` = `posts`.`category_id`
where `posts`.`category_id` in (id's from categories query)
limit 10;

Answer 3

First of all your relation name is wrong in your controller. Update your category model by the following code:
public function ten_posts()
{
return $this->hasMany(PostModel::class)->take(10);
}
then update your controller with the following code:
$categories = CategoriesModel::with('ten_posts')->take(6)->get();

Answer 4

Try like this -
$categories = CategoriesModel::with(['pages' => function($query) {
$query->take('10');
}])->take("6")->get();