how to deal with jsonp request in php using the Slim Framework?

Question

when i send a jsonp GET request with jQuery, it usually sends something like:

http://website.com/test?callback=jQuery20309569547907449305_1386221743664&id=9&limit=10&_=1386221743665

in Zend Framework i will handle this like:

$request  = $this->getRequest();
$callback = $request->getParam('callback');
$id       = $request->getParam('id');
$limit    = $request->getParam('limit');

// set $response var to something

$this->getResponse()->setBody($callback . '(' . json_encode($response) . ');');

in Slim Framework i have:

$callback = isset($_GET['callback']) ? $_GET['callback'] : '';
$app->get(
    '/test',
    function () {
        $resp = array('This is a TEST route');
    }
);
$app->response->setBody($callback . '(' . json_encode($resp) . ');');

but the route returns 404

any ideas how can i have this working?

Answer 1

For Slim 3.x Just add the middleware in the response chain

$app->add(function ($request, $response, $next) { // jsonp
    $callback = $_GET['callback'] ?? false;

    if($callback) $response->getBody()->write($callback."(");
    $response = $next($request, $response);
    if($callback) $response->getBody()->write(")");

    return $response;
});

Answer 2

Have you worked with zend before? I'm not quite sure if you know how zend works. You don't have any get() functions with callbacks, but rather you've got an controller (in your case: test ) and this controller has several actions.

an example for your text-controller with an example action could look something like this:

class TestController extends Zend_Controller_Action
{

    public function init()
    {
        //you might want to use here a contextSwitch 
    }

    public function fooAction()
    {
        //get params
        $limit = $this->_getParam('limit', 0);
        [...]

        //do stuff here
        [...]

        $this->_helper->json($response);
    }
}

Your calls to this action now might look like this:

http://website.com/test/foo/limit/10

Note that there is no need for ugly ?param=value in zend. simply append it to you URI with param/value

Note (important): There are several ways in zend to output json , therefore $this->_helper->json($response) might not be the best solution for you. Using a contextSwitch inside your init() function might be better.

Answer 3

There are several things wrong here. First, you should not be getting a 404, you should be getting an error complaining that $resp is not defined.

I think you are probably missing a .htaccess (or web.config if you are on IIS) that is routing all requests to your front controller file (where you define your Slim object and routes). To see if this is the problem, try http://website.com/index.php/test?callback=whatever , where index.php is the name of your front controller file.

This is the .htaccess that I use:

RewriteEngine On

#Slim PHP routing
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !^/index.php
RewriteRule ^ index.php [QSA,NC,L]

As for trying to achieve what you want to achieve, you need something like this:

$app = new Slim\Slim();

$app->get('/test', function () use($app) {

    //Request processing begins here...

    //Get callback from query string
    $callback = $app->request()->get('callback');

    //Check for null here...

    //Set content type to javascript
    header('Content-type: text/javascript');

    //Generate our JSONP output
    echo "$callback(" . json_encode(array('This is a test.')) . ");";

    //Request processing ends here...

});

$app->run();

I'm not 100% familiar with Zend, but I think it uses a more traditional MVC implementation where you have a Controller class that you extend and implement actions as methods. Slim is much more basic than that, instead you define routes on your app objects and map these to closures, which are executed when their route is hit.

In my example above, I define a closure for the route '/test'. Closures in PHP have no access by default to other variables in their scope. In order to access a variable outside of the closure scope we must explicitly specific the variables we want via the "use" keyword. In the example, I "use" the $app object, so that we can use the app object inside our closure. This is the basis for the majority of the functionality Slim provides. The $app object is the IOC object, the core where everything lives and should be used to expose service objects, etc. In this case, we are using the request() method that returns us a wrapper around the request related superglobals ($_GET, $_POST, etc).

Once we have our callback parameter, we can validate, and then generate and send our JSONP. Slim does not abstract (as far as I know) send data back down the response, you should just use echo as in vanilla PHP. You should also set the header type to javascript since that is what we are sending. Hope this helps.

Answer 4

I came across this answer while attempting to support JSONP responses in Slim v3.

The answer by @cardeol didn't quite support my needs as some of my earlier middleware calls made use of the "$response->withJson($data, $code);"

This call destroys and recreates the body object. Flushing any "BEFORE" writes.

class JSONPResponseMiddleware {
/**
 * Wrap response with callback query parameter
 *
 * @param  \Psr\Http\Message\ServerRequestInterface $request  PSR7 request
 * @param  \Psr\Http\Message\ResponseInterface      $response PSR7 response
 * @param  callable                                 $next     Next middleware
 *
 * @return \Psr\Http\Message\ResponseInterface
 */
public function __invoke(\Psr\Http\Message\ServerRequestInterface $request, \Psr\Http\Message\ResponseInterface $response, $next){
    if(!$callback = $request->getQueryParam("callback", false)){
        return $next($request, $response);
    }

    $response = $next($request, $response);
    $data = $response->getBody();

    // upstream controllers use "withJSON" which purges the existing body object.
    $body = new Body(fopen('php://temp', 'r+'));
    $body->write("{$callback}(");
    $body->write($data);
    $body->write(")");
    $response = $response->withBody($body)->withHeader('Content-type', 'application/javascript');
    return $response;
}

}

Then installed with: $app->add(new JSONPResponseMiddleware());