Laravel 4 Cache::remember is never returning a response with a given ID

I am using Laravel 4 in conjunction with the a PHP Shopify connector. I am trying to limit the calls made to retrieve Shopify products by caching the particular product pages when they are first needed.

I made the following simple route in Laravel to test this flow:

Route::get('product/{id}', function($id)
{
    $value = Cache::remember($id, 10, function() use ($id)
    {
        echo('Getting this from Shopify');
        $shopify = new ShopifyLib;
        return $shopify->getShopifyProduct($id);
    });

    var_dump($value);
});

ShopifyLib is a PHP library I wrote to communicate with the Shopify connector. The call returns a product page in JSON format correctly ever time. The problem is that the call is always being made externally to Shopify and not being retrieved from the cache.

I am using database caching with the following entry being saved:

key : laravel172989477
value : eyJpdiI6Imw4aUwzNHN4eExwdElPWFZKXC9hdFpVRjc4ZG5pK1dYMTlJVm44a1doKzlvPSIsInZhbHVlIjoieVJ6N2J6Q1A3SGNsWG1xWFJKTUdVak5FSEtHWDZKQkd2Y2x0ZEI2dHlvcz0iLCJtYWMiOiJhNWU0OGUxOTkyNWE2NTRhNTY1ZTNhMjRlOWNhNzRjNGI1ZDIyY2YzNGM3NTVjOThhMDUyYjllZmI1OTJiZmE1In0=
expiration : 1386616552

The $id never changes so I assume that this entry should be returned every time.

I tried a simpler example using:

Route::get('product/{id}', function($id)
{
    $value = Cache::remember('test', 5, function()
    {
        echo('Not getting this from the cache!');
        return 'example';
    });

    var_dump($value);
});

This worked as expected only calling the non-cache one time with all future calls going to the cache.

It turns out that the response coming back from Shopify was not actually JSON as I initially suspected. It was apparently an Array. By JSON encoding the response, the cache is working as expected.

Route::get('product/{id}', function($id)
{
    $value = Cache::remember("product_$id", 10, function() use ($id)
    {
        echo('Getting this from Shopify');
        $shopify = new ShopifyLib;
        return json_encode($shopify->getShopifyProduct($id));
    });

    var_dump(json_decode($value));
});