How to multi-callback a promise in AngularJs with $q? - angularjs

Question

I'm using the code below in order to simplify the backend requests but I didn't catch how to call either a success method or an error method.
How can I reach the expected behavior commented in the code?
app.factory('REST', function ($http, $q, sweetAlert) {
return {
load: function (module, action, data) {
var deferred = $q.defer();
var promise = deferred.promise;
$http
.post('/api/'+module+'.php?action='+action, data)
.success(function (data) {
if(data.error)
{
sweetAlert.swal({
title: "Error",
text: data.error,
type: "warning"
});
//HERE I WANT TO CALL .error(details)
}
else
deferred.resolve(data.result);
}).error(function () {
//HERE I WANT TO CALL .error(details)
});
promise.success = function(fn) {
promise.then(fn);
return promise;
}
return promise;
}
};
});
This is the code which uses the code above:
$scope.login = function () {
$scope.loading = true;
var payload = {'credentials': $scope.logindata};
REST.load('access', 'login', payload).success(function(data) {
if(data.redirect)
$state.go(data.redirect);
$scope.loading = false;
}).error(function(data) { //THIS SHOULD BE CALLED
$scope.loading = false;
});
}

Answer 1

First of all, I strongly discourage you from attaching .success to the promise you are returning. This is not Promises/A-compliant, and its subtle difference from .then (as is implemented by $http) causes a lot of confusion. Just return a pure promise.
Other than that, a few things to note:
1) you don't need another $q.defer and deferred.resolve() - just chain to the original promise of $http and return the resulting promise. (see deferred anti-pattern)
2) to reject a promise - that is, to cause the .catch (not .error - see above about the subtle difference) to fire - you should return $q.reject().
All of the above produces the following:
app.factory('REST', function($http, $q, sweetAlert){
return {
load: function(module, action, data) {
// this "return" returns the promise of $http.then
return $http.post('/api/' + module + '.php?action=' + action, data)
.then(function(response) {
var data = response.data; // .then gets a response, unlike $http.success
if (data.error) {
sweetAlert.swal({
title: "Error",
text: data.error,
type: "warning"
});
//HERE I WANT TO CALL .error(details)
return $q.reject(data.error);
}
return data.result; // what you would have "resolved"
});
}
};
})
Then, as I said above, use the .then/.catch as you would with promises:
$scope.login = function () {
$scope.loading = true;
var payload = {'credentials': $scope.logindata};
REST.load('access', 'login', payload)
.then(function(data) {
if(data.redirect)
$state.go(data.redirect);
$scope.loading = false;
})
.catch(function(error) {
$scope.loading = false;
});
}

Answer 2

Update yr code as below
app.factory('REST', function ($http, $q, sweetAlert) {
return {
load: function (module, action, data) {
var deferred = $q.defer();
$http.post('/api/'+module+'.php?action='+action, data)
.success(function (data) {
if(data.error)
{
sweetAlert.swal({
title: "Error",
text: data.error,
type: "warning"
});
//HERE I WANT TO CALL .error(details)
deferred.reject(data.error);
}
else{
deferred.resolve(data.result);
}
})
.error(function (error) {
//HERE I WANT TO CALL .error(details)
deferred.reject(error);
});
return defferred.promise;
}
};
});
for yr controller
$scope.login = function () {
$scope.loading = true;
var payload = {'credentials': $scope.logindata};
REST.load('access', 'login', payload).then(
function(data) {
if(data.redirect)
$state.go(data.redirect);
$scope.loading = false;
},
function(error) {
$scope.loading = false;
});
}