Question

I am trying to serve up my user repository via zend_json_server. The problem is the service is returning empty objects. What have i missed?
server side:

$repo = App_User_Repository::getInstance();

  $server = new Zend_Json_Server();
  $server->setClass($repo);

  if ('GET' == $_SERVER['REQUEST_METHOD']) {
      $server->setTarget('/service/json-rpc.php')
             ->setEnvelope(Zend_Json_Server_Smd::ENV_JSONRPC_2);
      $smd = $server->getServiceMap();

      // Set Dojo compatibility:
      $smd->setDojoCompatible(true);
      header('Content-Type: application/json');
      echo $smd;
      return;
  }

  $server->handle();

client side:

    var object = new dojo.rpc.JsonService('/service/json-rpc.php');
    var deferred = object.getById(1);
    deferred.addBoth(function(result) {console.log(result)});

Firebug console output:

 Object {}

This should be a User object

Answer 1

When doing the actual RPC with the “getById()” method, an dojo.deferred object is returned. At this point, a asynchronous request is running. By using the deferred object, you can define callbacks and error handlers in advance whilst waiting for the response to be returned.

Check if the actual response object isn’t empty as well. Remember, you still have to use the return keyword in your attached classes to return results back to Zend_Json_Server. Zend_Json_Server will then serialize and send back the returned value automatically. A response from Zend_Json_Server is always a serialized object in JSON, containing an id (which increments automatically with each request), an string indicating what jsonrpc version is being used (ie. 2.0) and of course a result containing the returned data from the attached class.

The setClass() method should not be a object instance, but a string containing the className of the class you want to attach. Zend_Json_Server handles the creation of the object instance by itself, as well as generating the SMD (Service Method/Mapper Description). Remember to document each public method with docblocks, as Zend_Json_Server uses those docblocks to determine the SMD.

Furthermore, it is much more handy to use a fluent-like interface with the then() method like so:

var myService = new dojo.rpc.JsonService('/service/json-rpc.php?');
var deferredObj = myService.doThis('myArgument');
deferredObj.then(callback, errorHandler).then(afterCallback).then(cleanUp);

In above example, the variables callback, errorHandler, afterCallback and cleanUp, are actually references to functions. The first then() method you call, automatically passes the rpc result to the callback function. If you throw an exception from within the attached rpc class, the errorHandler method (second optional argument of the first then() method call) will be called instead.

More information: http://www.sitepen.com/blog/2010/05/03/robust-promises-with-dojo-deferred-1-5/