AngularJS: Returning a promise from within .then?

Question

I have a users service. I would like to create a method which utilizes another service I have built. There are two methods on this service. getUser() and getCurrentUser(). getCurrentUser() utilizes the injected service which acquires the UID. It uses the returned UID to run the getUser() method. My problem is that I can't get getCurrentUser() to return the second tier promise.

This question is a little bit difficult to explain. Here's the code...

svs.service("usersService", function($rootScope, $http, loginService, alertBoxService) {
  var self = this;
  self.getUser = function(identifier, column) {
    if (typeof(column) === 'undefined') column = "uid";
    return $http.get($rootScope.api + "/getUser/" + identifier + "/" + column);
  }
  self.getCurrentUser = function() {
    var currentUserPromise;
    loginService.getCurrentUid().then(
      function(response) {
        if (response.data === "false") {
          alertBoxService.trigger($rootScope.unexpectedApiResponse);
        } else {
          console.log(self.getUser(response.data));
          currentUserPromise = self.getUser(response.data);
        }
      }, function(response) {
        alertBoxService.trigger($rootScope.asyncFailed);
      }
    );
    return currentUserPromise;
  }
});

Answer 1

Chain the promises but don't forget to chain the rejections too...

self.getCurrentUser = function() {
    return loginService.getCurrentUid().then(function(response) {
        if (response.data === 'false') {
            alertBoxService.trigger($rootScope.unexpectedApiResponse);
            return $q.reject(response); // convert into a rejection
        }
        return self.getUser(response.data); // chain the promise resolution
    }, function(response) {
        alertBoxService.trigger($rootScope.asyncFailed);
        return $q.reject(response); // chain the rejections
    });
}

You'll need to inject the $q service of course.

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As Bergi kindly pointed out, you can also reject the promise by throwing an error instead of using $q.reject, eg

throw response;