Challenge with delayed function execution in AngularJS

Question

Challenge with delayed function execution in AngularJS

In my Angular application, I am encountering a problem in the following scenario.

There are three crucial files:

MainCtrl.js

Upon loading the application, the init() function in MainCtrl.js is triggered, which then calls the flowService as shown below:

flowService.configureSteps();

This call to the flowService initiates a server request to fetch data.

FlowService.js

function configureSteps() {
    salesService.getSalesOrder().then(function(response) {
            salesService.setSalesOrder(response);
    });
}

The response received from the server is stored in the salesOrder variable within the service for later retrieval.

SubCtrl.js

Within the initialization of SubCtrl, an attempt is made to access the saved salesOrder from the service.

function init() {
   salesService.getSalesOrder();
}

Issue

When accessing the URL like this:

http://www.myapp.com/review#/subpage

MainCtrl is invoked
The service is called for data and a server request is initiated
Due to the asynchronous nature of the call, control passes to SubCtrl before the data is retrieved
As a result, an attempt to retrieve the salesOrder that hasn't been fetched yet leads to an issue

How can this process be made synchronous?

javascript angularjs ajax asynchronous

Answer 1

Answer №1

Utilize events to notify the subCtrl.js that the data has been received. While it's still running within the $digest cycle, you can easily manage the user interface of subCtrl.js. Make sure to inject $rootScope into both the controller and service.

flowService.js

function configureSteps() {
    salesService.getSalesOrder().then(function(response) {
            salesService.setSalesOrder(response);
            $rootScope.$emit('order-recieved');
    });
}

subCtrl.js

function init() {
   $rootScope.$on('order-recieved',function(){
      salesService.getSalesOrder();
   })
}

Answer 2

Utilize events to notify the subCtrl.js that the data has been received. While it's still running within the $digest cycle, you can easily manage the user interface of subCtrl.js. Make sure to inject $rootScope into both the controller and service.

flowService.js

function configureSteps() {
    salesService.getSalesOrder().then(function(response) {
            salesService.setSalesOrder(response);
            $rootScope.$emit('order-recieved');
    });
}

subCtrl.js

function init() {
   $rootScope.$on('order-recieved',function(){
      salesService.getSalesOrder();
   })
}

Answer 3

Answer №2

If you want to optimize your code, consider moving the mainCtrl.js flowService.configureSteps() call to one of the following locations:

the resolve state function (UI-Router)
$routeChangeStart event callback (NgRoute)

By utilizing a resolve function in UI-Router state, you can perform tasks prior to accessing the specified state, allowing for synchronous operations before the controller is instantiated.

In this scenario, ensure that you execute your flowService.configureSteps() before entering the mainCtrl, and run salesService.getSalesOrder() prior to accessing the subCtrl (after saving the previous order).

Alternatively, with ngRoute, define a routeChange callback as follows:

$rootScope.$on("$routeChangeStart", function (event, currentRoute, previousRoute) {
    //
});

Within this callback, perform any necessary logic prior to route activation, ensuring all required data is available upon page load.

Feel free to share your route/state configuration if you require further assistance.

Answer 4

If you want to optimize your code, consider moving the mainCtrl.js flowService.configureSteps() call to one of the following locations:

the resolve state function (UI-Router)
$routeChangeStart event callback (NgRoute)

By utilizing a resolve function in UI-Router state, you can perform tasks prior to accessing the specified state, allowing for synchronous operations before the controller is instantiated.

In this scenario, ensure that you execute your flowService.configureSteps() before entering the mainCtrl, and run salesService.getSalesOrder() prior to accessing the subCtrl (after saving the previous order).

Alternatively, with ngRoute, define a routeChange callback as follows:

$rootScope.$on("$routeChangeStart", function (event, currentRoute, previousRoute) {
    //
});

Within this callback, perform any necessary logic prior to route activation, ensuring all required data is available upon page load.

Feel free to share your route/state configuration if you require further assistance.

Answer 5

Answer №3

I have utilized promises in my implementation.

progressService.js

 function establishProgress() {
        var progressPromise = progressService.getProgressStatus().then(function(response) {
                progressService.updateProgress(response);
        });
        return progressPromise ;
    }

salesService.setPromise(establishProgress()); // Assigns the promise to a service

subCtrl.js

function initialize() {
 salesService.getPromise().then(function() {
       progressService.fetchProgressStatus(); // This will only happen upon successful resolution of the promise.
    });

}

Implement the setPromise and getPromise functions in the service.

Answer 6

I have utilized promises in my implementation.

progressService.js

 function establishProgress() {
        var progressPromise = progressService.getProgressStatus().then(function(response) {
                progressService.updateProgress(response);
        });
        return progressPromise ;
    }

salesService.setPromise(establishProgress()); // Assigns the promise to a service

subCtrl.js

function initialize() {
 salesService.getPromise().then(function() {
       progressService.fetchProgressStatus(); // This will only happen upon successful resolution of the promise.
    });

}

Implement the setPromise and getPromise functions in the service.

Challenge with delayed function execution in AngularJS

Answer №1

Answer №2

Answer №3

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