Laravel 5.4 Take json array of id's

i have two tables

1.Categories [id(int),photo_id(int),name(string),created_ad(datetime),updated_at(datetime)]

2.Items [id(int),category_id(int),photo_id(int),name(string),description(text),created_ad(datetime),updated_at(datetime)]

my Category model

    class Category extends Model
   {

    protected $fillable = ['name', 'photo_id'];


    public function photo()
    {

        return $this->belongsTo('App\Photo');

    }
}

my Items model

   class Items extends Model
{
    //

    protected $fillable = [
        'name', 'category_id', 'photo_id', 'description'
    ];


    public function category()
    {

        return $this->belongsTo('App\Category');

    }


    public function photo()
    {

        return $this->belongsTo('App\Photo');

    }
} 

i just want to give items more then one id of category if its only one id i know how to display this

$item->category->name (give me the name of category from category table)

but, if i want more than one how can i do this ?

1. i trying to take collumn category_id and make it to string type than take all ids in json , its work but than how i display this in view ?

2.i cant make in database column type json this is mariaDB.

ty for helper :)

via Chebli Mohamed