Laravel 4：选择多对多关系

Question

I work on a blog project, which have relation many to many between "posts" and "cats" tables (with pivote table)

posts:
    id
    title
    topic

cats:
    id
    name

cat_post:
    post_id
    cat_id

I prepare models correctly, so, how to select all posts in specific category? I tried:

Cat::with('post')->where('id', '=', '3')->get();

and

Post::with('cat')->whereId('3')->get();

but nothing yet,

Answer 1

This is better/shorter:

$cats = Cat::with('post')->find(3);

Update:

$cats = Cat::with(array('post' => function($q) { // make sure posts not post
    $q->orderBy('id', 'desc'); // order the posts
}))->find(3); // No need to order a single model

Answer 2

just found the answer

$cats = Cat::with('post')->whereId(3)->first();

then retrive it in blade:

@foreach($cats->post as $post)
    {{$post->title}}
@endforeach

thanks,