php - Passing array in many to many relationship to the controller- laravel -

i have many many relationship between category , posts tables this:

category class:

class category extends model { public function posts()     {     //return $this->hasmany('app\posts','category_id');     return $this->belongstomany('app\posts', 'categories_post', 'category_id', 'post_id')     ->withtimestamps();     } } 

posts class:

class posts extends model {    public function category()    {     //return $this->belongsto('app\category','category_id');     return $this->belongstomany('app\category', 'categories_post', 'post_id', 'category_id')     ->withtimestamps();    } } 

when need access 1 category's posts in controller:

    public function cat($category_id) { $posts= $category_id->posts()->paginate(7); return view('cat')->with('posts',$posts); } 

edit

to make work, added in "routeserviceprovider.php" file:

    public function boot(router $router) {     parent::boot($router);     $router->model('categories','app\category'); } 

and works perfectly. problem is, i have controller should posts multiple categories :

    public function index() {     $title = 'news';     $categories= [1, 2, 10, 11];     // here problem:     $posts= $categories->posts()->paginate(7);     return view('news')->with('posts',$posts)->with('title',$title); } 

this gives me error: call member function posts() on non-object

i know there wrong calling array, don't know how solve it. can 1 me please :)

---

the solution

after thomas van der veen said in answer , came controller working perfectly:

    public function index() {     $title = 'news';     $category_ids = [1, 2, 10, 11];     $posts = posts::wherehas('category', function($query) use ($category_ids) { $query->wherein('id', $category_ids);     })->get();     return view('news')->with('posts',$posts)->with('title',$title); } 

you like:

$category_ids = [1, 2, 10, 11];  $posts = post::wherehas('categories', function($query) use ($category_ids) {      $query->wherein('id', $category_ids);  }); 

see this.