eloquent 获得所有类别的 4 个帖子

Question

i have some categories and many posts in each category i want to get all categories with its last 4 posts

my code with eloquent is:

$allcats = Category::whereHas('posts')->with(['posts' => function($q){
            $q->take(4);
}])->get();

but the problem is: this query will take just and just 4 post (4 post from all of the categories)

can do this with eloquent? or can id do this with query builder??

Answer 1

From the Laravel docs on Constraining Eager Loads

[!] The limit and take query builder methods may not be used when constraining eager loads.

So you would have to create another relationship method on your class Category like this

public function lastPosts()
{
  return $this->hasMany('App\Post')->take(4);
}

then use it instead

$allcats = Category::whereHas('posts')->with('lastPosts')->get();

Or use a raw query

$allcats = Category::whereHas('posts')->with(['posts' => function($q){
            $q->orderBy('created_at')->selectRaw('max(4)');
}])->get();

Hope this helps