Angular promise did not assign a value to a variable

Question

Angular promise did not assign a value to a variable

Can someone assist me with a problem I'm facing? After the first callback, the variable doesn't seem to change as expected. Below is my code snippet:

    this.handlerLocalDef = function(defer) {
        var hash = {};

        defer.then(
               function(response) {
                   hash = response;
               },
               function(err) {
                   showPopup(err);
               }
        );

        return hash;
    };

    var initialized = function()  {
        var localRegDef = Localization.getLocalizedDefer('regularform'),
            localPaymDef = Localization.getLocalizedDefer('payment');

            localizeRegForm = self.handlerLocalDef(localRegDef);

            $timeout(function() {
                console.log("localizeRegForm", localizeRegForm);
            }, 5000);
   }();

Upon checking the console log, it shows `localizeRegForm: {}`

javascript angularjs

Answer 1

Answer №1

Simply assigning hash = response only changes the reference of the local variable, not the original object itself. To properly update the original object with the values from response, you can use angular.extend(hash,response);. This will effectively copy all members of response into the hash object, ensuring that the receiver sees these changes.

Note: Be aware that this method may not work for primitive values (strings, numbers, booleans, etc.) or arrays.

Here is a fiddle showcasing the suggested approach: http://jsfiddle.net/sVRCg/3/

If you have concerns about how to verify that hash has been extended with response, using polling like setTimeout is not ideal. Consider returning a promise instead to accurately track when the response is ready.

Alternatively, explore implementations similar to how ngResource handles this process, although it may involve more complexity in the code structure.

Answer 2

Simply assigning hash = response only changes the reference of the local variable, not the original object itself. To properly update the original object with the values from response, you can use angular.extend(hash,response);. This will effectively copy all members of response into the hash object, ensuring that the receiver sees these changes.

Note: Be aware that this method may not work for primitive values (strings, numbers, booleans, etc.) or arrays.

Here is a fiddle showcasing the suggested approach: http://jsfiddle.net/sVRCg/3/

If you have concerns about how to verify that hash has been extended with response, using polling like setTimeout is not ideal. Consider returning a promise instead to accurately track when the response is ready.

Alternatively, explore implementations similar to how ngResource handles this process, although it may involve more complexity in the code structure.

Answer 3

Answer №2

Async programming should not involve setting arbitrary timeouts and hoping for data at a specific point in time. It's important to use deferred objects as intended and utilize callbacks for more reliable functionality. Here is a suggestion on how you can restructure your code to ensure it works properly, although effectiveness may vary based on your unique circumstances:


    this.handlerLocalDef = function(defer,callback) {

        defer.then(
               function(response) {
                   callback.apply(this,[response])
               },

               function(err) {
                   showPopup(err);
               }
        );

    };



    var initialized = function()  {
        var localRegDef = Localization.getLocalizedDefer('regularform'),
            localPaymDef = Localization.getLocalizedDefer('payment');


            self.handlerLocalDef(localRegDef,function(response) {
                console.log(response);
            });
   }();

Answer 4

Async programming should not involve setting arbitrary timeouts and hoping for data at a specific point in time. It's important to use deferred objects as intended and utilize callbacks for more reliable functionality. Here is a suggestion on how you can restructure your code to ensure it works properly, although effectiveness may vary based on your unique circumstances:


    this.handlerLocalDef = function(defer,callback) {

        defer.then(
               function(response) {
                   callback.apply(this,[response])
               },

               function(err) {
                   showPopup(err);
               }
        );

    };



    var initialized = function()  {
        var localRegDef = Localization.getLocalizedDefer('regularform'),
            localPaymDef = Localization.getLocalizedDefer('payment');


            self.handlerLocalDef(localRegDef,function(response) {
                console.log(response);
            });
   }();

Angular promise did not assign a value to a variable

Answer №1

Answer №2

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