I'm new in AngularJS so if the question is not 'intelligent' for you, please don't rate it in negative. If someone ask a question, for he isn't stupid.
So..
I would like to use data from an ajax request, like this:
encryptApp.factory('getData', function($http, $rootScope) {
var getData = {};
getData.tot_of = function() {
return $http.get('/path/to').then(function(result) {
return result.data;
});
}
getData.get_info = function() {
return $http.get('/path/to').then(function(result) {
return result.data;
});
}
return getData;
});
In controller I use this:
getData.get_info().then(function(get_info) {
$scope.get_info = get_info;
});
// HERE THE $scope.get_info is UNDEFINED
I'm new in AngularJS and I don't know why does this. So, is there a method that I can use the json data outside the " then function ".
Thanks and please don't rate this question negative. Sorry if my english is not good.
$http.get returns a promise.
By essence, a promise is as Javascript saying:
"Hey ! I let you make the request, but please, I don't want to wait for you, so when you finished, please execute the callback I'm just passing you, since now, I will forget you since I have more code to execute while you're doing your job".
In other words, a promise's callback isn't executed immediately, since the goal is to not block the Javascript "thread" (Javascript is like single-threaded).
So your current code is acting like this:
getData.get_info().then(function(get_info) { //the function inside this "then" IS the callback
$scope.get_info = get_info;
});
// Hey !! The request might not finish ! So don't expect $scope to have the value you expect here !
So the simple example to illustrate would be to imagine that your ajax request takes 100ms to execute.
Within those 100ms, your next Javascript scope is very very very likely to be already reached, having $scope.get_info not initialized yet.
Without promise, your next code, outside of the callback, that should not depend of $scope.get_info, would have to wait 100ms to start, wasting time.
So, is there a method that I can use the json data outside the " then
function ".
There is a way, using broadcasting/emit ($rootScope.$broadcast/$rootScope.$emit) to trigger a corresponding event, but it's often more "anti-KISS" for a simple case.
I advise you to put all your depending code in the promise callback.
To clean your code, merely call a private function that you define outside the callback.
Related
I'm having a hard time understanding how unit testing with Karma+Jasmine works exactly
I'm trying to setup some Unit Tests for my AngularJS app but I'm running into a problem where the Tests don't seem to run a function properly.
I have a function that reads a json file through a $http.get request and populates an array, but when I set up in my unit test to expect the length of the array expect(array.length).toBe(10), it always fails, yet that is the length of the array when I run the App normally. Actually if I print the length in the console.log on the unit test it seems to always be stuck at 1.
But for example if I check some of the variables I declare manually then the expect function works properly.
Can anyone tell me what exactly am I missing here? It's seems i'm missing some of the fundamentals on how unit testing with Karma/Jasmine works.
Any help would be greatly appreciated. Thanks!
Your problem is that $http.get is an asynchronous method. Unless you sepcifically tell angularjs that it needs to flush that response, it will not. The method will exit and the callback of $http.get will not happen in time for your it method to utilize its $scope transformations.
You can achieve this by expecting the call to happen with the $httpBackend API https://docs.angularjs.org/api/ngMockE2E/service/$httpBackend
You can then do
$httpBackend.expectGET('../json/apps.json').respond(200, {mock: 'api response');
$scope.getAllApps();
$httpBackend.flush();
expect(scope.allApps.length).toBe(10);
In your unit tests you should never rely on the actual response of http calls. To ensure you are testing only the method you should always mock the response of what your API is supposed to return.
ERRONEOUS
$scope.getAllApps = function(){
$scope.isLoading = true;
$http.get('../json/apps.json').then(function (data){
// ...
});
$scope.isLoading = false;
};
BETTER
$scope.getAllApps = function(){
$scope.isLoading = true;
$http.get('../json/apps.json').then(function (data){
// ...
}).finally(function() {
$scope.isLoading = false;
});
};
Because the $http service in non-blocking and asynchronous, it immediately returns a promise. It does not wait for data to return from the server. The isLoading flag needs to wait for the promise to resolve before setting the flag false.
I had an issue with and angular-meteor project flickering every time a state using the campaigns subscription, would load. By flickering, I mean the data was there, then it would go away and come back a half second later.
I added this to the resolve property of the state (using ui-router):
campaigns: ($q) => {
var deferred = $q.defer();
Meteor.subscribe('campaigns', {
onReady: deferred.resolve,
onStop: deferred.reject
});
return deferred.promise;
}
The flickering stopped, but I don't really understand this code. Can someone who understand angular break this resolve/defer situation down?
Just not sure why it worked. thanks.
$q is angular's implementation of promises.
in a very itty bitty nutshell, a promise has two callbacks that resolve when data is returned; a resolve function if the call succeeds and a reject if the call fails. whatever data it gets will be passed into these functions (essentially doing deferred.resolve(data) or deferred.reject(error)) . $q.defer() allows us to assign the resolution/rejections later.
meteor's subscribe function takes a few arguments. the string name of the collection, a function that returns an array of arguments to be passed to the collection, and an object/function. the object part of the final argument expects an "onReady" and "onStop" functions, and will execute those functions and pass along any data it gets. we pass in our callbacks here.
finally, we return the promise. resolve.campaigns will be a promise, which we can get the values from using the .then(successCallback, failureCallback) call. meteor handles this behind the scenes.
I have a function in my controller that calls an api to retrieve some values:
$scope.Refresh= function(){
$http.get('/get/value')
.success(function(data) {
//some actions
})
.error(function(data) {
//some actions
});
} ;
I want to refresh the values occasionally, so I've done:
setInterval($scope.Refresh, 100000);
I will do in a better way, but now I want to solve this.
but there is a problem:
If, in the controller, I say: $scope.Refresh (to execute the function first time), the controller does nothing.
If I write the same function + setInterval (to test and run it) it works first time (outside the function), but never refresh next times (code function inside), to explain, that execute the function but neither .success nor .error is called.
I have seen the headers with a 304 status (not modified) but the values are modified!!
I tried to disable cache but that did not fix the problem.
I tried to give a random value to the route like: /get/value/(randomNuber) but I get nothing
Where is the problem?
Just running:
$scope.Refresh();
should definitely run the function at least once. If it doesn't something is wrong with your code or with your server route. But you should be getting a console error if that's the case.
For setInterval, you should be using the $interval service that ensures your code is run within the angular loop.
Also, per the documentation, you should explicitly cancel this interval when your controller is destroyed.
var httpInterval = $interval($scope.Refresh, 100000);
$scope.$on('$destroy', function() {
$interval.cancel(httpInterval);
});
I've only had intermittent luck with .success and .error, and I'd like to think that part of it was caching the request. I have very consistent, successful results using .then, as shown:
$scope.Refresh= function(){
var myGet = $http.get('/get/value');
myGet.then(function(data){
//do success things here
}, function(data){
//do error things here
});
};
Other than that, follow the advice that #theJoeBiz gave regarding $interval and you should be fine.
i'm using angularJS and SLIM PHP restful server, the PHP service is working and actually i have already used $http.get() with no problems in this application ...
But now a strange thing is happening, i created a new function in the same way that the others, and it get .success(function(data)) with no problems, i actually can console.log(data) and it shows the right results, but when .success() finish and return, i recieve a undefined result.
ps: there is no error in browser console.
var markerOptions = [];
loadMarkers();
console.log(markerOptions);
function loadMarkers() {
$http.get('http://localhost/rest/getMarkers').success(function(response){
console.log(response);
markerOptions = response;
});
}
Console.log() inside success() return the right data
Console.log() after loadMarkers() return undefined
#MarcKline's comments are correct. Anyways, following what I think you're trying to achive by this piece of code of yours, you can assign the returned data from the ajax response to a scope variable (assuming you're using $scope), e.g $scope.markerOptions = response. You can declare markOptions as a scope variable by var $scope.markOptions = [] (...and, of course, log it by console.log($scope.markOptions) accordingly). Also, define $scope.loadMarkers = function() {...} and call it by $scope.loadMarkers()
The scope will be updated as soon as the client-side gets its ajax response.
Hope it helps your current needs in addition to a better understanding of javasciprt's async approach that some of its principles were explained to you by the comments.
I need to execute a function which is defined in controller in load-time, in order to gain json data from another place right after page is loaded.
I've tried to call the func immediately within controller, now i feel it was bad idea.
When something bad is happen and exception is raised - the controller stops working.
Well, not big surprise, but at the moment i don't have idea how work it out.
Ofcourse, i can wrap possible dangerous code in try-catch, but that's definetely not best solution imho.Here's the sample code:
app.controller("ServerStatusCtrl",
function($scope) {
$scope.reloadFunc = function()
{
throw "dat bad exception";
}
$scope.reloadFunc(); // Let's pretend that it's needed 2 call this function in load-time.
});
And example on jsfiddle
I advice you to use $q's way of notifying that something happen: return promise and reject it after something wrong happen.
This is the way how exception handling is done in async/promise way.
General idea is:
Instead of returning result, function should return promise
When you have your data ready (loaded from server) you resolve promise
If something bad happen you reject it.
function someFunc() {
var d = $q.defer();
do.somethingAsync(function(result) {
if (somethingWrong) d.reject(result);
else d.resolve(result);
});
return d.promise;
}
And in controller:
$scope.myData = someFunc().then(function ok(result) { return ok.data; }, function faled() { handle...});
This gives a good control on error handling/recovery.
Found easier solution for this.
Just discovered a ngInit directive which solved the whole problem.
Also, i think that module.run(fn) would be also applicable for this kind of tasks.