Avoiding a repeated call to same API in AngularJS from 2 controllers during page load

Question

I have a single page app built using AngularJS. When the page first loads, there are two controllers that execute and these are 'Controller1' and 'Controller2'.

Each of them needs to make a call to the same WebAPI in order to meet its logic requirements.
Also, 'Controller1' code executes first, but due to the async nature of the code, 'Conroller2' code starts to execute before the Controller1 call to WebAPI has returned successfully.

Question: How can I make sure that only Controller1 makes the call to WebAPI, so that Controller2 simply uses the call in Controller1 rather than making a repeated call?

Controller1

dashboardDataService.getAllDashboards().then(onDashboardListReceived)

Controller2

dashboardDataService.getAllDashboards().then(onDashboardListReceived)

Mathew Berg · Accepted Answer · 2015-05-16 12:29:11Z

5

.service('dashboardDataService', function($http){
    var dashboardDataServiceScope = this;

    var allDashboardsPromise = false;

    dashboardDataServiceScope.getAllDashboards = function(){
        if(!allDashboardsPromise){
            allDashboardsPromise = $http.post(...);
        }
        return allDashboardsPromise;
    };
});

What this will do will create a promise the first time, and then every time something else calls it will just return the same promise. So you can have multiple hooked into one.

edited May 16, 2015 at 12:29

answered May 15, 2015 at 15:58

Mathew Berg

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2 Comments

Sunil Over a year ago

Shouldn't ' return allDashboardsDeferred.promise' be just ' return allDashboardsDeferred', since allDashboardsDeferred becomes a promise when used with $http.post(...).then(...)?

Mathew Berg Over a year ago

You're right, I had initially wired it up with $q :)

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