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Reuse Services without circular dependencies

I have one service that is globally storing all my data used through out my app.
GlobalDataService (GDS)
angular
.module('app.core')
.service('GlobalDataService', GlobalDataService);
GlobalDataService.$inject = ['$http', 'LineStatusService'];
function GlobalDataService($http, LineStatusService) {
var gds = this;
gds.data = {
//all my data
}
gds.data.lines = LineStatusService.getLineStatus().then...
}
And a simple crud service that handles the Status of my data.
StatusDataService (SDS)
angular
.module('app.core')
.service('LineStatusService', LineStatusService);
LineStatusService.$inject = ['$http', 'GlobalDataService'];
function LineStatusService($http, GlobalDataService) {
var service = {
getLineStatus: getLineStatus,
saveLineStatus: saveLineStatus,
...
};
function saveLineStatus (line, status, user) {
var data = {
status: {
status_id: status.status_id,
status_desc: status.status_desc
},
updated_by: user
}
return $http.post('/api/euauto/v1/delivery-status/linestatus', data)
.then(function successCallback(response) {
GlobalDataService.data[id].status = status;
return response.data;
}).catch(function errorCallback(response) {
});
}
return service;
}
The GDS has to request all Status's when the app first loads, then the Status Service handles any other data requests.
Now I understand you can't have circular dependencies, therefore my plan was to have my Controller handle the save and update using SDS and ALSO update the GDS.
Potential Solution
angular
.module('core')
.controller('MyController', MyController);
MyController.$inject = ['GlobalDataService', 'LineStatusService'];
function MyController(GlobalDataService, LineStatusService) {
function changeStatus(line, status, user) {
//do a thing
//and another
LineStatusService.saveLineStatus(line, status, user);
GlobalDataService.data.line[id] = status;
GlobalDataService.updateAllOtherData();
//etc...
}
}
The Problem
My question is, now I want to develop a new Controller which contains the exact same functionality I will now have to remember to copy the same code and business logic from my original Controller to reuse both Services.
Also, if the GDS doesn't depend on SDS it won't be able to getLineStatus() on load and each Controller in the app will have to remember to getLineStatus() on load.
Ideally all the logic and requests should be contained in one place, preferably my SDS. My GDS data should be consistent across the whole Application.

If GlobalDataService is supposed to be initialized with data when the app starts, then you could initialize it in a .run() block instead of in the service constructor. That way the GDS does not need to have the other services injected at all. The other data services can then have GDS injected without circular dependency issues.
angular
.module('app.core')
.run(function(GlobalDataService, LineStatusService) {
GlobalDataService.data.lines = LineStatusService.getLineStatus().then...
});

How to persist data in a service on refresh in AngularJS?

I'm creating a new multi-use website for a new brand my company is launching in a few weeks. We use a WordPress backend and via the WP REST API, are now able to uncouple the system and use NodeJS/Express/AngularJS for our front end and middleware applications.
Currently, when I load the landing page, an HTTP GET Request is made to WordPress for all of the relevant posts for our front page. This data is then passed to a service to be used across controllers.
So, the initial set up is this:
landingController
angular
.module('glossy')
.controller('LandingController', LandingController)
LandingController.$inject = ['featuredService', 'sharedPostsService'];
function LandingController(featuredService, sharedPostsService){
// Set up view model (vm) variables
var vm = this;
vm.featured = [];
// Call this function on state 'home' load
activate();
// Calls getFeatured function and prints to console
function activate(){
return getFeatured()
.then(function(){
console.log('GET Featured Posts');
});
}
// Calls the featuredService then stores response clientside for rendering
function getFeatured(){
return featuredService.getFeatured()
.then(function(data){
vm.featured = data;
sharedPostsService.setPosts(data);
return vm.featured;
});
}
}
Factory for HTTP Request
angular
.module('glossy')
.factory('featuredService', featuredService)
featuredService.$inject = ['$http'];
function featuredService($http){
return {
getFeatured: getFeatured
};
// Performs HTTP request then calls success or error functions
function getFeatured(){
return $http.get('/api/posts')
.then(getFeaturedComplete)
.catch(getFeaturedFailed);
// Returns response data
function getFeaturedComplete(response){
return response.data;
}
// Prints error to console
function getFeaturedFailed(error) {
console.log('HTTP Request Failed for getFeatured: ' + error.data);
}
}
}
Service that holds data from factory
angular
.module('glossy')
.factory('sharedPostsService', sharedPostsService)
function sharedPostsService(){
var listPosts = [];
return {
setPosts: function(posts){
listPosts = posts;
},
getPosts: function(){
return listPosts;
}
};
}
Now, when a user clicks on a post on the landing page, she is taken to a page that displays on the article that she clicked on, which works. However, if she refreshes this page, all the data is gone. Calling the service results in an empty object.
Post controller
angular
.module('glossy')
.controller('PostController', PostController)
PostController.$inject = ['$window', '$filter', '$stateParams', 'sharedPostsService'];
function PostController($window, $filter, $stateParams, sharedPostsService){
var vm = this;
vm.postsList = sharedPostsService.getPosts();
vm.postTitle = $stateParams.title;
vm.thisPost = filterPosts();
function filterPosts() {
return $filter('filter')(vm.postsList, vm.postTitle);
};
}
How do I set this up to ensure that the data persists through refresh? I looked into using localStorage but everything I found said it involved stringifying data and storing it in key value pairs?
Any help is appreciated.

You cannot use a service to persist data on a page refresh.
If the data is large use a database, else use sessionStorage or localStorage.
Storing the data:
window.localStorage['data'] = JSON.stringify(data);
Retrieving the data:
return angular.fromJson(window.localStorage['data']);

Angularjs: load data in service then load it to controllers

I've checked several solutions on the web but I don't quite understand how to stop the controllers from loading. So, I've created a plunkr to highlight what I want to do.
Basically: I want to load all data in a service and then pass around that data from that service to each controller. When the app first loads, because it's Async, the controllers are loaded first.
I could have just used the factory in each controller, but I want to hold that data in the "allProducts" property of the service. I don't see the need to call the factory function each time a view loads.
In the example, I've also tried with the $q service, but seems to me it has the same behaviour just like the http from the factory and still needs to call the http request on each view load...
So, could somebody help me with this example and implement an elegant solution?
app.factory('productsFactory', ['$http', '$q',
function($http, $q) {
var cachedData; //here we hold the data after the first api call
function getData(callback) {
if (cachedData) {
callback(cachedData);
} else {
$http.get('http://api.bestbuy.com/v1/products(longDescription=iPhone*|sku=7619002)?show=sku,name&pageSize=15&page=5&apiKey=bqs7a4gwmnuj9tq6bmyysndv&format=json')
.success(function(data) {
cachedData = data; //caching the data in a local variable
callback(data);
});
}
}
return {
getProds: getData
}
}
])
app.service('appService', ['productsFactory', '$q',
function(productsFactory, $q) {
var _this = this;
productsFactory.getProds(function(data) {
_this.allProducts = data; //wait for data to load before loading the controllers
})
}
])
app.controller('productsCtrl', ['$scope', 'appService',
function($scope, appService) {
$scope.myProducts = appService.allProducts;
}
]);
plunkr here: http://plnkr.co/edit/ZvtYwXHSasC3fCAZKkDF?p=preview

I didn't actually test it, but looks like you need to create and return a promise in order to have the data returned when it's available.
app.factory('productsFactory', ['$http', '$q',
function($http, $q) {
var cachedData; //here we hold the data after the first api call
function getData(callback) {
var d = $q.defer();
if (cachedData) {
d.resolve(callback(cachedData));
} else {
$http.get('http://api.bestbuy.com/v1/products(longDescription=iPhone*|sku=7619002)?show=sku,name&pageSize=15&page=5&apiKey=bqs7a4gwmnuj9tq6bmyysndv&format=json')
.success(function(data) {
cachedData = data; //caching the data in a local variable
d.resolve(callback(cachedData));
});
}
return d.promise;
}
return {
getProds: getData
}
}
])
app.service('appService', ['productsFactory', '$q',
function(productsFactory, $q) {
var _this = this;
productsFactory.getProds(function(data) {
_this.allProducts = data; //wait for data to load before loading the controllers
})
}
])
app.controller('productsCtrl', ['$scope', 'appService',
function($scope, appService) {
$scope.myProducts = appService.allProducts;
}
]);

Check this: http://plnkr.co/edit/ey0na3l2lyT0tUdbDyrf?p=preview
Changes:
- a main app controller that wraps all your app.
In this controller we prevent route change if the boot hasn't finished all its jobs. When boot is finished, we change location to the main/default route.
- in our run block we set the bootStatus var to false and wait until products are fetch.
Also, I've stored the result from service to $rootScope so you can use that data in all your controllers without injecting the service over and over again.

FINALLY!!! I Managed to do what I was looking for.
Note, this is not necessarily a best practice, but it was a problem that was bugging me and wanted to know how it's done.
The way I did it was to create a global variable, where I use a main resolve function to wait for the factory to do the http get and then pass it to the service. Then, I use resolve on every state where I need that data and reference that function.
UPDATE: Realized that I was calling the same factory function each time the state was changins, so I decided to go with a variable - a property in the appService which turns to true when the http get was called once: appService.retrieved and changed the main resolve function a bit.
var mainResolve = ['$q', 'appService', 'productsFactory', function($q, appService, productsFactory) {
var defer = $q.defer();
if(appService.retrieved) {
defer.resolve();
} else {
productsFactory.getProds(function(data) {
appService.allProducts = data;
defer.resolve();
})
appService.retrieved = true;
}
return defer.promise;
}]
And in the state
.state('home', {
url: "/home",
templateUrl: "home.html",
controller: 'homeCtrl',
resolve: {
waitingFor: mainResolve
}
})
You can find the plnkr with the working solution, here: http://plnkr.co/edit/ZvtYwXHSasC3fCAZKkDF?p=preview
Again, the factory could be refactored some more and eliminate some code like the caching data. This way, we only go once to the factory function.

Angular - Best practice for retrieving data from a Factory method

I'm looking for some information on the best way to retrieve data from a local JSON file and handle the response. After browsing through Stack Overflow, I have some mixed thoughts as I've seen multiple ways of doing the same thing (although no explanation on why one may or may not be preferred).
Essentially, I have an Angular app that is utilising a factory to retrieve data from a JSON file; I'm then waiting for the response to resolve in my controller before using it in my html file, similar to the below:
Option 1
Factory:
comparison.factory('Info', ['$http', function($http) {
var retrievalFile = 'retrievalFile.json';
return {
retrieveInfo: function() {
return $http.get(retrievalFile);
}
}
}]);
Controller:
comparison.controller('comparisonController', ['$scope', 'Info', function($scope, Info) {
Info.retrieveInfo().then(function(response) {
$scope.info = response.data;
});
}]);
My main point of contention is figuring out when it's best to wait for the response to resolve, or if it even matters. I'm toying with the idea of having the factory return the fulfilled promise, and wait for the controller to retrieve the data also. In my view, it's best to abstract all data retrieval out of the controller and into the factory, but I'm not sure if this extends to waiting for the actual data to be returned within the factory itself. With this in mind, I'm confused about whether to opt for option 1 or option 2 and would really appreciate some feedback from more experienced/qualified developers!
Option 2
Factory:
comparison.factory('Info', ['$http', function($http) {
var retrievalFile = 'retrievalFile.json';
return {
retrieveInfo: function() {
return $http.get(retrievalFile).then(function(response) {
return response.data;
});
}
}
}]);
Controller:
comparison.controller('comparisonController', ['$scope', 'Info', function($scope, Info) {
Info.retrieveInfo().then(function(response) {
$scope.info = response;
});
}]);
Thank you for any input/suggestions in advance!

It depends on what your controller is expecting and how you set up your application. Generally, I always go with the second option. Its because I usually have global error or success handlers in all api requests and I have a shared api service. Something like below.
var app = angular.module('app', []);
app.service('ApiService', ['$http', function($http) {
var get = function(url, params) {
$http.get(url, { params: params })
.then(handleSuccess, handleError);
};
// handle your global errors here
// implementation will vary based upon how you handle error
var handleError = function(response) {
return $q.reject(response);
};
// handle your success here
// you can return response.data or response based upon what you want
var handleSuccess = function(response) {
return response.data;
};
}]);
app.service('InfoService', ['ApiService', function(ApiService) {
var retrieveInfo = function() {
return ApiService.get(retrievalFile);
/**
// or return custom object that your controller is expecting
return ApiService.get.then(function(data) {
return new Person(data);
});
**//
};
// I prefer returning public functions this way
// as I can just scroll down to the bottom of service
// to see all public functions at one place rather than
// to scroll through the large file
return { retrieveInfo: retrieveInfo };
}]);
app.controller('InfoController', ['InfoService', function(InfoService) {
InfoService.retrieveInfo().then(function(info) {
$scope.info = info;
});
}])
Or if you are using router you can resolve the data into the controller. Both ngRouter and uiRouter support resolves:
$stateProvider.state({
name: 'info',
url: '/info',
controller: 'InfoController',
template: 'some template',
resolve: {
// this injects a variable called info in your controller
// with a resolved promise that you return here
info: ['InfoService', function(InfoService) {
return InfoService.retrieveInfo();
}]
}
});
// and your controller will be like
// much cleaner right
app.controller('InfoController', ['info', function(info) {
$scope.info = info;
}]);

It's really just preference. I like to think of it in terms of API. What is the API you want to expose? Do you want your controller to receive the entire response or do you want your controller to just have the data the response wraps? If you're only ever going to use response.data then option 2 works great as you never have to deal with anything but the data you're interested in.
A good example is the app we just wrote where I work. We have two apps: a back-end API and our front-end Angular application. We created an API wrapper service in the front-end application. In the service itself we place a .catch for any of the API endpoints that have documented error codes (we used Swagger to document and define our API). In that .catch we handle those error codes and return a proper error. When our controllers/directives consume the service they get back a much stricter set of data. If an error occurs then the UI is usually safe to just display the error message sent from the wrapper service and won't have to worry about looking at error codes.
Likewise for successful responses we do much of what you're doing in option 2. In many cases we refine the data down to what is minimally useful in the actual app. In this way we keep a lot of the data churning and formatting in the service and the rest of the app has a lot less to do. For instance, if we need to create an object based on that data we'll just do that in return the object to the promise chain so that controllers aren't doing that all over the place.

I would choose option two, as it your options are really mostly the same. But let see when we add a model structure like a Person suppose.
comparison.factory('Info', ['$http', function($http) {
var retrievalFile = 'retrievalFile.json';
return {
retrieveInfo: function() {
return $http.get(retrievalFile).then(function(response) {
//we will return a Person...
var data = response.data;
return new Person(data.name, data.age, data.gender);
});
}
}
}]);
This is really simple, but if you have to map more complex data into object models (you retrieve a list of people with their own items... etc), that's when things get more complicated, you will probably want to add a service to handle the mapping between data and models. Well you have another service DataMapper(example), if you choose your first option you will have to inject DataMapper into your controller and you will have to make your request through your factory, and map the response with the injected service. And then you probably say, Should I have all this code here? ... Well probably no.
That is an hypothetical case, something that count a lot is how you feel structuring your code, won't architecture it in a way you won't understand. And at the end take a look at this: https://en.wikipedia.org/wiki/SOLID_(object-oriented_design) and research more information about this principles but focused to javascript.

Good question. A couple of points:
Controllers should be view centric versus data centric therefore you
want remove data logic from the controller and rather have it focus
on business logic.
Models (M in MVC) are a data representation of your application and
will house the data logic. In Angular case this would be a service
or factory class as you rightfully pointed out. Why is that well for
example:
2.1 AccountsController (might have multiple data models injected)
2.1.1 UserModel
2.1.2 AuthModel
2.1.3 SubscriptionModel
2.1.4 SettingsModel
There are numerous ways to approach the data model approach, but I would say your service class should be the data REST model i.e. getting, storing, caching, validating, etc. I've included a basic example, but suggest you investigate JavaScript OOP as that will help point you in the right direction as to how to build data models, collections, etc.
Below is an example of service class to manage your data.Note I have not tested this code but it should give you a start.
EXAMPLE:
(function () {
'use strict';
ArticleController.$inject = ['$scope', 'Article'];
function ArticleController($scope, Article) {
var vm = this,
getArticles = function () {
return Article.getArticles()
.then(function (result) {
if (result) {
return vm.articles = result;
}
});
};
vm.getArticles = getArticles;
vm.articles = {};
// OR replace vm.articles with $scope if you prefer e.g.
$scope.articles = {};
$scope.userNgClickToInit = function () {
vm.getArticles();
};
// OR an init on document ready
// BUT to honest I would put all init logic in service class so all in calling is init in ctrl and model does the rest
function initArticles() {
vm.getArticles();
// OR chain
vm.getArticles()
.then(getCategories); // doesn't here, just an example
}
initArticles();
}
ArticleModel.$inject = ['$scope', '$http', '$q'];
function ArticleModel($scope, $http, $q) {
var model = this,
URLS = {
FETCH: 'data/articles.json'
},
articles;
function extract(result) {
return result.data;
}
function cacheArticles(result) {
articles = extract(result);
return articles;
}
function findArticle(id) {
return _.find(articles, function (article) {
return article.id === parseInt(id, 10);
})
}
model.getArticles = function () {
return (articles) ? $q.when(articles) : $http.get(URLS.FETCH).then(cacheArticles);
};
model.getArticleById = function (id) {
var deferred = $q.defer();
if (articles) {
deferred.resolve(findArticle(id))
} else {
model.getBookmarks().then(function () {
deferred.resolve(findArticle(id))
})
}
return deferred.promise;
};
model.createArticle = function (article) {
article.id = articles.length;
articles.push(article);
};
model.updateArticle = function (bookmark) {
var index = _.findIndex(articles, function (a) {
return a.id == article.id
});
articles[index] = article;
};
model.deleteArticle = function (article) {
_.remove(articles, function (a) {
return a.id == article.id;
});
};
}
angular.module('app.article.model', [])
.controller('ArticleController', ArticleController)
.service('Article', ArticleModel);
})()

Using angularJS smart table

I would like to use AngularJS smart table for my site. I have gone through the documentation(smart table). Having hard time to understand how does the app.factory works here. I want to know how to implement createRandomItem function for the data I have in the database(mongodb).
app.factory('Resource', ['$q', '$filter', '$timeout', function ($q, $filter, $timeout) {
//this would be the service to call your server, a standard bridge between your model an $http
// the database (normally on your server)
var randomsItems = [];
function createRandomItem(id) {
var heroes = ['Batman', 'Superman', 'Robin', 'Thor', 'Hulk', 'Niki Larson', 'Stark', 'Bob Leponge'];
return {
id: id,
name: heroes[Math.floor(Math.random() * 7)],
age: Math.floor(Math.random() * 1000),
saved: Math.floor(Math.random() * 10000)
};
}
for (var i = 0; i < 1000; i++) {
randomsItems.push(createRandomItem(i));
}
//fake call to the server, normally this service would serialize table state to send it to the server (with query parameters for example) and parse the response
//in our case, it actually performs the logic which would happened in the server
function getPage(start, number, params) {
var deferred = $q.defer();
var filtered = params.search.predicateObject ? $filter('filter')(randomsItems, params.search.predicateObject) : randomsItems;
if (params.sort.predicate) {
filtered = $filter('orderBy')(filtered, params.sort.predicate, params.sort.reverse);
}
var result = filtered.slice(start, start + number);
$timeout(function () {
//note, the server passes the information about the data set size
deferred.resolve({
data: result,
numberOfPages: Math.ceil(filtered.length / number)
});
}, 1500);
return deferred.promise;
}
return {
getPage: getPage
};
}]);

Ok... My Time to Shine.. :D.... Just kidding.. you answer is bellow..
Well this a fairly straight forward example, if you are familiar with angular factory.
when you use a factory service it executes the code inside the factory's definition and return whatever you would just like calling a function.
So what the above code is doing is when you use this factory service simply generates a list of random items(Avengers) into the array randomItems that step is fairly simple. if you look at the createRandomItem(id) and the for loop after it.
the trick however is in getPage() and what the Resource factory is returning. So lets go on a journey.
in the code where Resource factory is used when you call Resourse.getPage() it'll return a promise object on which you can call other JS functions. and inside getPage() as you can see it has set a timeout to call resolve with an object that has variables data and numberOfPages in it, on the deffered object which triggers doneCallback on the promise of that deffered object.
so when you service like
Resourse.getPage(1,2,3) // please see the use of these arguments inside the getPage function
.done(function(result){
result.data; //the fake server data from the factory
result.numberOfPages; //this is computed in factory as well
});
When 1500ms pass the function/callback passed to done gets trigerred.
Summary and Answer
Note: Please read above first it took me hell of a time to write that.
Now to address your problem. what you can do is modify this
app.factory('Resource', ['$q', '$filter', '$timeout', function ($q, $filter, $timeout)
to
app.factory('Resource', ['$http', '$q', '$filter', '$timeout', function ($http, $q, $filter, $timeout)
an use $http to retrieve data from the server or mongodb and fill in an array with your data from server.
$http.get(server_url).success(function(response){
//....do something with the response from the server like filtering etc..
//finally..
deferred.resolve({
data: response
});
});
an finally when using service
Resourse.getPage(1,2,3) //what ever you want to pass its not necessory to pass the same as above
.done(function(response){
//do what ever you want to do with response from your factory.. PHEW...
});
P.S.0. its the longest answer I've provided to date.. PHEW :P
P.S.1. Please feel free to ask any question in the comments