Sharing data between AngularJS services

Question

Is there a way to share data between services in AngularJS?

Use case: data aggregation from different services
For example I want a service1 that loads some data from a REST Service. Then another service2 adds additional data to the service1 data from another REST API to create a data aggregation service.

I basically want to separate the services based on the APIs that they use, but still have a service that holds all the data in the end.

Answer 1

Create a third service that uses the $q deferred library to combine the promises from the 2 API REST calls using $q.all().

Then pass this third service to your controller as a dependency and use $q.then() to combine the results:

var app = angular.module('angularjs-starter');
app.factory('API_1',function($http){ 
 return $http.get('dataSource-1.json'); 
})
app.factory('API_2',function($http){ 
 return $http.get('dataSource-2.json'); 
});
app.factory('API_3',function($q,API_1,API_2){ 
 return $q.all([API_1,API_2]);
})
/* add "$q" and "API_3" as dependencies in controller*/
app.controller('MainCtrl', function($scope,$q,API_3) {
 $q.when(API_3).then(function(results) {
 /* combine the 2 API results arrays*/
 $scope.combinedData=[results[0].data,results[1].data]; 
 }); 
});

DEMO: Plunker Demo

Answer 2

Since a service can depend on another service, this will work:

myApp.factory('myService1', function() {});
myApp.factory('myService2', function(myService1) {});

Note that they can't both depend on each other, or you'll get a Circular dependency error.