CODEWITHSUNDEEP
javascriptangularjs
user3127896
user3127896

Reputation: 6593

angular promise then issue

Playing around with angular resource i cant figure out why it works this way. I have following code (let's assume that query function works fine):

$scope.getSomething = function (someObject) {
    var result;
    Factory.getSomething.query({ id: someObject.id }).$promise.then(function (success) {
        alert('success');
        result = 'success';
    },
    function(error) {
        alert('error');
        result = 'error';
    });
    alert(result);
};

When i execute this method i get following: 1) Alert with undefined 2) Alert with 'success'

Why undefined is first? As I understand $promise right, then 

alert('success');
result = 'success';

should work first if succeed (when asynchronous is executed). Then should be invoked last alert with result value. But seems like it works not like i am expecting.

Any suggestions? Thanks in advance.

Upvotes: 1

Views: 83

Answers (3)

Jesse Carter
Jesse Carter

Reputation: 21207

Unless there's a particular reason that you need to deal with the raw $promise returned by $resource I find it a lot easier to just use the built in success/failure handlers.

Factory.getSomething.query({id: someObject.id}, function(data) {
    // this will be asynchronously called when the API call returns with success. data is your payload
}, function(error) {
    // this will be asynchronously called when the API call returns with error
});

Upvotes: 0

Stu
Stu

Reputation: 2446

The promise means that while it's processing it allows other code to run. Therefore while your getSomething request is being processed on the server your browser is running the rest of the code, in this case the alert(result).

At that point result hasn't yet been assigned so it's undefined. Then your web service returns, and the success code runs with runs the "success" alert which is the second alert message you're getting.

Upvotes: 2

Chrillewoodz
Chrillewoodz

Reputation: 28368

You are alerting result before it's defined, therefore you get an alert with undefined. result only gets a value after the async operation has been completed, either in your then or error.

Upvotes: 0

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