TokenMismatchException in VerifyCsrfToken.php line 67 using Route::post() - php

Question

I understand that this is a common issue with Laravel 5.x, but my particular run-in with the problem is not through submitting a form.
Instead, I am using postman to send data to a URL endpoint to test if data is successfully received. I'm working with Laravel 5.2 and I'm very much new to it!
Here is my routes.php file (related content)
Route::group(['middleware' => 'web'], function () {
Route::post('/cart', 'CartController#buildcart');
});
Here is my CartController.php (entire file)
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Requests;
class CartController extends Controller
{
public function buildcart(){
echo 'hello';
}
}
As simple as that is, when I use postman to send random data to the /cart URL, I get
TokenMismatchException in VerifyCsrfToken.php line 67:
Can anyone help me understand why this is failing? I don't see how using
{{ csrf_token() }}
is the solution for this case since the data is coming from an external source.
Running list of things I've tried
Removing the route from Route::group(['middleware' => 'web'], function () {
using Route::group(array('before' => 'csrf', ['middleware' => 'web']), function () {

Answer 1

try add the route to this route group
Route::group(array('before' => 'csrf', ['middleware' => 'web']), function () {
Route::post('/cart', 'CartController#buildcart');
});
EDIT : try to comment this line in app\kernel.php
protected $middlewareGroups = [
'web' => [
\App\Http\Middleware\EncryptCookies::class,
\Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
\Illuminate\Session\Middleware\StartSession::class,
\Illuminate\View\Middleware\ShareErrorsFromSession::class,
// \App\Http\Middleware\VerifyCsrfToken::class,
],
'api' => [
'throttle:60,1',
],
];

Answer 2

Try changing the middleware in the routes.php file. I think, you are getting the error as you are not authorized to use the route. Try this:
Route::group(['middleware' => 'guest'], function () {
Route::post('/cart', 'CartController#buildcart');
});