Angularjs: Store $resource data in service to share across controllers

Question

Short question: Is it possible to store the data from $resource in a service, so as to query once and use it in different controllers?

I tried query().$promise.then, but still resource is returning an empty reference. What is the correct syntax to resolve and store the $resource data in a service, such that subsequent calls can make use of it?

factory('DataService', function($resource) {
    var resource = $resource("/api/data", {}, {
        query: { isArray: false }
    });

    var data;
    return {
        get: function (args) {
            if (!data) {
                resource.query().$promise.then(
                    function(result) {
                        data = result.message;  
                        return data;
                    }
                );  
            }
            return data;
        }
    }; 

Answer 1

Is it possible to store the data from $resource in a service, so as to query once and use it in different controllers?

Yes, but I'd have it store the promise so then you've got a consistent API. For example

.factory('DataService', function($resource) {
    // $resource definition here

    var promise;

    return {
        get: function() {
            if (!promise) {
                promise = resource.query().$promise.then(function(result) {
                    return result.message;
                });
            }
            return promise;
        }
    };
})

Then everything else can use

DataService.get().then(function(message) {
    // do stuff with message
})

and it will only be retrieved once.

You can create a new promise chain (using then) from the original promise as many times as you want and it will always resolve with the same, original result.message value