$q promises for async calls

[pspeter3]

Looking through the code, I'm trying to understand how difficult it would be to wrap the async calls to facebook with $q and tie in the events to the angular event system. Thoughts?

[pc035860]

Hello @pspeter3, thank you for asking!

After looking through the code, you'll find out that the current callback function's angular context application($rootScope.$apply) is actually determined by the user.

The wrapped $FB APIs try to extract the arguments from your input, find out any is function argument, then $apply the angular context to it.

angular.forEach(args, function (arg, i) {
  /**
   * Wrap API function arg with angularjs context
   */
  if (angular.isFunction(arg)) {
    var func = arg;
    args[i] = function () {
      var funcArgs = Array.prototype.slice.call(arguments);

      if ($rootScope.$$phase) {
        // already in angularjs context
        func.apply(null, funcArgs);
      }
      else {
        // not in angularjs context
        $rootScope.$apply(function () {
          func.apply(null, funcArgs);
        });
      }
    };
  }
});

So the difficulty for returning $q promise is

If there's no callback function presented, wrapper function wouln't know where to $apply angular context, hence failing to resolve the $q promise

And I come up with a solution for that - always present the original callback function with an angular.noop(empty function) or a null value. Here's an example how it will look like after implementation:

/**
 * Modified API demo
 */
$FB.getLoginStatus(null)
.then(function (res) {
  $scope.loginStatus = res;

  return $FB.api('/me', null);
})
.then(function (res) {
  $scope.apiMe = res;
});

/**
 * Combined with $q.all
 */
$q.all([
  $FB.api('/me', null),
  $FB.getLoginStatus(null, true),
  $FB.ui(options, null)
])
.then(function (rsvList) {

  var apiMeRes = rsvList[0],
      loginStatusRes = rsvList[1],
      uiRes = rsvList[2];

});

Otherwise, I'll have to specify which argument in each method is the callback function in reference to Facebook JavaScript SDK doc.

[pspeter3]

Fair enough, do you think it's worth specifying it?

[pc035860]

Sure. I'll try to implement the feature this weekend.

[pspeter3]

Thanks!

[pc035860]

Hi @pspeter3 ,

I just pushed the version supports $q promise to develop branch,
please try it and let me know whether it works well or not.
And I'll merge it to master if it does work well, thanks!!

Here's an new version of demo for $q promise version
http://plnkr.co/edit/UMUtFc?p=preview

The develop version of includable scripts are available at

• http://pc035860.github.io/angular-easyfb/angular-easyfb.dev.js
• http://pc035860.github.io/angular-easyfb/angular-easyfb.dev.min.js

[pspeter3]

That looks awesome. Thank you!