In replied to Mulia Nasution as response to my work partner Syaifudin Latief.

ResourceController.php

<?php

namespace App\Http\Controllers\Cart;

use Illuminate\Support\Facades\View;
use App\Http\Requests\Cart\StoreRequest;
use Illuminate\Support\Facades\Redirect;
use App\Http\Requests\Cart\UpdateRequest;
use App\Cart\Persistances\Cart as Persistant;
use App\Cart\Repositories\Cart as Repository;

/**
 * In replied to Mulia Nasution <https://www.facebook.com/groups/laravel/permalink/639129009558792>
 * as response to my work partner Syaifudin Latief. Ini hanya gambaran kasar aja,
 * dan GAK akan langsung works di coding-an kalian, dengan kata lain, ini semacam
 * pseudo code.
 *
 * @author Krisan Alfa Timur <krisan47[at]gm*il[dot]c*m>
 *
 * @see https://laravel.com/docs/5.2/facades Facades
 * @see https://laravel.com/docs/5.2/validation#form-request-validation Form Request Validation
 */
class ResourceController
{
    /**
     * Fungsi dari object ini untuk fetch data aja dari database. Sifatnya read only.
     *
     * @var \App\Cart\Repositories\Cart
     */
    protected $repository;

    /**
     * Fungsi dari object ini untuk menulis data ke database. Sifatnya read and write.
     *
     * @var \App\Cart\Persistances\Cart
     */
    protected $persistant;

    /**
     * Class constructor. Inject semua kebutuhan controller di sini.
     *
     * @param \App\Cart\Repositories\Cart $repository Fetch data (Read only).
     * @param \App\Cart\Persistances\Cart $persistant Persistant data (Read and write).
     */
    public function __construct(Repository $repository, Persistant $persistant)
    {
        $this->repository = $repository;

        $this->persistant = $persistant;
    }

    /**
     * Tampilin single resource. Untuk mencari cart yang mau kita tampilin,
     * kita bisa menggunakan method 'get' di class 'Repository'.
     *
     * @param int $id ID cart di database
     *
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        $cart = $this->repository->get($id);

        return View::make('cart.show', compact('cart'));
    }

    /**
     * Tampilin list cart yang ada. Untuk mencari daftar cart yang mau kita
     * tampilin, kita bisa menggunakan method 'all' di class 'Repository'.
     *
     * @return \Illuminate\Http\Response
     */
    public function search()
    {
        $carts = $this->repository->all();

        return View::make('cart.list', compact('carts'));
    }

    /**
     * Tambah cart baru.
     *
     * @return \Illuminate\Http\Response
     */
    public function add()
    {
        return View::make('cart.add');
    }

    /**
     * Simpen cart baru ke database melalui 'Persistant' class.
     *
     * @param \App\Http\Requests\Cart\StoreRequest $request Untuk validasi input dan allowing request.
     *
     * @return \Illuminate\Http\Response
     */
    public function store(StoreRequest $request)
    {
        $this->persistant->store($request->only([
            'foo', // nama field
            'bar', // nama field
            'baz', // nama field
        ]));

        return Redirect::to('/cart/list');
    }

    /**
     * Tampilin form untuk edit cart. Untuk mencari cart yang mau kita edit,
     * kita bisa menggunakan method 'get' di class 'Repository'.
     *
     * @param int $id ID cart di database.
     *
     * @return \Illuminate\Http\Response
     */
    public function edit($id)
    {
        $cart = $this->repository->get($id);

        return View::make('cart.edit', compact('cart'));
    }

    /**
     * Update cart ke dalam database melalui 'Persistant' class.
     *
     * @param int                                   $id      ID cart di database.
     * @param \App\Http\Requests\Cart\UpdateRequest $request Untuk validasi input dan allowing request.
     *
     * @return \Illuminate\Http\Response
     */
    public function update($id, UpdateRequest $request)
    {
        $this->persistant->update($id, $request->only([
            'foo', // nama field
            'bar', // nama field
            'baz', // nama field
        ]));

        return Redirect::to('/cart/list');
    }

    /**
     * Delete cart di database melalui 'Persistant' class.
     *
     * @param int $id ID cart di database.
     *
     * @return \Illuminate\Http\Response
     */
    public function delete($id)
    {
        $this->persistant->delete($id);

        return Redirect::to('/cart/list');
    }
}