How to make a then function work?

Question

I'm trying to create a delete service with angular.

Here is my controller :

app.controller('VoirMessagesController', function($scope, $rootScope, $routeParams, $location,$translate, userService, dataRefreshServices){
    $scope.messageToWatch = dataRefreshServices.getMessageToWatch();


    this.DeleteAMessage = function(){
        dataRefreshServices.SupprimerMessage($scope.messageToWatch).then(function(){
            $location.path('/messages'); // The problem is here
        });
    };


});

and the service called :

$this.SupprimerMessage = function(message){
        var retour = true;
        if(message != undefined)
        {
            $translate(['MESSAGES_MESSAGERIE_SUPPRIMER', 'BUTTON_CANCEL', 'MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TEXTE', 'MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TITRE']).then(function(translations)
            {
                    var modalOptions = {
                closeButtonText: translations.BUTTON_CANCEL,
                actionButtonText: translations.MESSAGES_MESSAGERIE_SUPPRIMER,
                headerText: translations.MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TITRE,
                bodyText: translations.MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TEXTE
                };

                // displaying the modal box
                modalYesNoService.showModal({}, modalOptions).then(function (result) {              

                    var index = _.indexOf(listeMessages, _.find(listeMessages, function (_message) { return _message._id == message._id; }));
                    $this.SupprimerMessageFromServer(message).then(function(promise){
                        listeMessages[index]._id = 0;

                    });
                });
            });
        }
        return retour;
    };

I get the error :

undefined is not a function
    at DeleteAMessage 

I understand that my function doesn't return any promise but I don't know how I could make this work, I just want my redirection with $location.path done only if the user has clicked on yes in my modal windows.

I wanted to add a "then" to wait the answer of the user before doing the redirection.

It looks like I should create a promise but can't figure how I can "create" a promise. When I use $http.get I understand what's in the promise but here I can't (before no data is expected, I just want to know when the user has clicked on yes).

Thank you

Answer 1

You're trying to call .then() on a bool, which of course isn't going to work. The AngularJS documentation includes very easy-to-understand examples on using $q (its flavor of promises).

From the docs:

// for the purpose of this example let's assume that variables `$q` and `okToGreet`
// are available in the current lexical scope (they could have been injected or passed in).

function asyncGreet(name) {
  var deferred = $q.defer();

  setTimeout(function() {
    deferred.notify('About to greet ' + name + '.');

    if (okToGreet(name)) {
      deferred.resolve('Hello, ' + name + '!');
    } else {
      deferred.reject('Greeting ' + name + ' is not allowed.');
    }
  }, 1000);

  return deferred.promise;
}

var promise = asyncGreet('Robin Hood');
promise.then(function(greeting) {
  alert('Success: ' + greeting);
}, function(reason) {
  alert('Failed: ' + reason);
}, function(update) {
  alert('Got notification: ' + update);
});

Answer 2

Here is how you would introduce promise (with $q service) in your script :

$this.SupprimerMessage = function(message){
        //var retour = true;//no more need
        var defer = $q.defer(); //inject $q into your service via dependency injection - here create a promise
        if(message != undefined)
        {
            $translate(['MESSAGES_MESSAGERIE_SUPPRIMER', 'BUTTON_CANCEL', 'MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TEXTE', 'MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TITRE']).then(function(translations)
            {
                    var modalOptions = {
                closeButtonText: translations.BUTTON_CANCEL,
                actionButtonText: translations.MESSAGES_MESSAGERIE_SUPPRIMER,
                headerText: translations.MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TITRE,
                bodyText: translations.MESSAGES_MESSAGERIE_MESSAGE_VALIDATION_SUPPRESSION_TEXTE
                };

                // displaying the modal box
                modalYesNoService.showModal({}, modalOptions).then(function (result) {              

                    var index = _.indexOf(listeMessages, _.find(listeMessages, function (_message) { return _message._id == message._id; }));
                    $this.SupprimerMessageFromServer(message).then(function(promise){
                        listeMessages[index]._id = 0;
                        defer.resolve({message:"Message corectly deleted"});
                    },function(){//this is the error callback if you used $http for SupprimerMessageFromServer
                        defer.reject({error:"Something went wrong while deleting message"});
                    });
                });
            });
        }
        else{
            defer.reject({error:"No message defined"});//this will go to the error callback of the promise
        }
        return defer.promise;//whatever return a promise on which you'll be able to call .then()
    };

Answer 3

Just add a parameter (function type) for callback

$this.SupprimerMessage = function(message, callback){
....
/* user pressed ok */
listeMessages[index]._id = 0;
callback();
....
}

$this.DeleteAMessage = function(){
    dataRefreshServices.SupprimerMessage($scope.messageToWatch, function() {
        $location.path('/messages');        
    });
};