Question

We are creating a gadget for the opensocial API 0.7.
In some functions we have to decide, if the viewer is the owner.

We couldn’t use the usual function for this purpose:
return gadgets.util.getUrlParameters().viewer == gadgets.util.getUrlParameters().owner;
so we had to create a workaround and get the information via a DataRequest.

The DataRequest calls a callback function and has no useable return value.
We tried a quick hack by using global variables to set the corresponding value.

The issue at this point is, that the function does not ‘wait’ for the callback-function to be finished. We know this is no good code/style at all, but we tried to force a timeout for debug reasons.

Handling all the code within the callback-function (as suggested in the examples of the opensocial docs) is not possible.
We are looking for something like a real ‘sleep()’ in JavaScript to wait for the callback-function to complete or another alternative to get the owner information about the viewer.

globalWorkaroundIsOwner = false;  

function show_teaser(){  
  if (current_user_is_owner()){  
    // ...  
  }  
  // ...  
}  

function current_user_is_owner() {  

  var req = opensocial.newDataRequest();  
  req.add(req.newFetchPersonRequest(opensocial.DataRequest.PersonId.VIEWER), 'viewer');  

  // This will set the the correct value  
  req.send( user_is_owner_workaround );  

  // This is an attempt to delay the return of the value.  
  // An alert() at this point delays the return as wanted.  
  window.setTimeout("empty()", 2000);  

  // This return seems to be called too early (the variable is false)  
  return globalWorkaroundIsOwner;  
}  

function user_is_owner_workaround(dataResponse) {  
  var viewer = dataResponse.get('viewer').getData();  

  globalWorkaroundIsOwner = viewer.isOwner();  
  // value is correct at this point  
}

Answer 1

Can you use an additional flag in order to indicate whether the remote query has already returned the required value?

var globalWorkaroundIsOwner = false;
var workaroundStarted = false, workAroundComplete = false;
var checker;

function show_teaser(){
    if (!workaroundStarted) {
        workaroundStarted = true;
        current_user_is_owner();
    }
    if (workaroundComplete) {  
    if (globalWorkaroundIsOwner){  
        // ...  
    }  
    // ...  
      if (checker) {
      clearInterval(checker);
      }
    }
}  

function current_user_is_owner() {  

    var req = opensocial.newDataRequest();  
    req.add(req.newFetchPersonRequest(opensocial.DataRequest.PersonId.VIEWER), 'viewer');  

    checker = setInterval("show_teaser()", 1000);
    // This will set the the correct value  
    req.send( user_is_owner_workaround );  
}  

function user_is_owner_workaround(dataResponse) {  
    var viewer = dataResponse.get('viewer').getData();  

    globalWorkaroundIsOwner = viewer.isOwner();  
    workAroundComplete = true;
    // value is correct at this point  
}