Slim Framework middleware array json manipulation

Question

I am trying to implement a simple middleware in Slim Framework that adds an array element in the response body. Without the middleware I am getting correct result as {"mytest":"running"}. What I really want is to have the middle ware merge another element and make it as {"mytest":"running","MODE":"development"}. Instead, I am getting this result {"0":"{\"mytest\"","1":"\"running\"}","MODE":"development"} .

I am definitely missing something very simple. Please have a look below for the code I am using. I guess I am not able to convert the body to an array.

This is what I am doing:

index.php

require 'Vendor/Slim/Slim.php';
\Slim\Slim::registerAutoloader();

$app = new \Slim\Slim();

//Middleware
$app->add(new \Slim\Middleware\TestMiddleware());

 // Middleware Test
    $app->get( 
        '/mid',
        function () use ($app) {
          $response = $app->response();
          $response->body(json_encode(array(
                'mytest'=>'running'
                )));

        }
    );

TestMiddleware.php

namespace Slim\Middleware;

//Appends mode to the response bpoy
class TestMiddleware extends \Slim\Middleware
{
    public function call()
    {
        $app=$this->app;

        $this->next->call();

        $res=$app->response;
        $body=$res->getBody();
        $res->setBody(
            json_encode(
                     array_merge(
                       explode(":",$body),array(
                'MODE'=>'development'
            )))
        );

    }

}

Answer 1

Instead of explode try to decode your json before to merge arrays:

json_encode(
    array_merge(
        json_decode($body,true),
        array('MODE'=>'development')
    )
)

DEMO