I'd like to do simple notifications in angular. Here is the code I've written.
http://pastebin.com/zYZtntu8
The question is:
Why if I add a new alert in hasAlerts() method it works, but if I add a new alert in NoteController it doesn't. I've tried something with $scope.$watch but it also doesn't work or I've done something wrong.
How can I do that?
Check out this plnkr I made a while back
http://plnkr.co/edit/ABQsAxz1bNi34ehmPRsF?p=preview
I show a couple of ways controllers can use data from services, in particular the first two show how to do it without a watch which is generally a more efficient way to go:
// Code goes here
angular.module("myApp", []).service("MyService", function($q) {
var serviceDef = {};
//It's important that you use an object or an array here a string or other
//primitive type can't be updated with angular.copy and changes to those
//primitives can't be watched.
serviceDef.someServiceData = {
label: 'aValue'
};
serviceDef.doSomething = function() {
var deferred = $q.defer();
angular.copy({
label: 'an updated value'
}, serviceDef.someServiceData);
deferred.resolve(serviceDef.someServiceData);
return deferred.promise;
}
return serviceDef;
}).controller("MyCtrl", function($scope, MyService) {
//Using a data object from the service that has it's properties updated async
$scope.sharedData = MyService.someServiceData;
}).controller("MyCtrl2", function($scope, MyService) {
//Same as above just has a function to modify the value as well
$scope.sharedData = MyService.someServiceData;
$scope.updateValue = function() {
MyService.doSomething();
}
}).controller("MyCtrl3", function($scope, MyService) {
//Shows using a watch to see if the service data has changed during a digest
//if so updates the local scope
$scope.$watch(function(){ return MyService.someServiceData }, function(newVal){
$scope.sharedData = newVal;
})
$scope.updateValue = function() {
MyService.doSomething();
}
}).controller("MyCtrl4", function($scope, MyService) {
//This option relies on the promise returned from the service to update the local
//scope, also since the properties of the object are being updated not the object
//itself this still stays "in sync" with the other controllers and service since
//really they are all referring to the same object.
MyService.doSomething().then(function(newVal) {
$scope.sharedData = newVal;
});
});
The notable thing here I guess is that I use angular.copy to re-use the same object that's created in the service instead of assigning a new object or array to that property. Since it's the same object if you reference that object from your controllers and use it in any data-binding situation (watches or {{}} interpolation in the view) will see the changes to the object.
Related
I'm using ruby on rails with angularjs one, and testing it with teaspoon-jasmine for the first time and am running into issues. Basically, I have a controller that creates an empty array and upon load calls a factory method to populate that array. The Factory makes an http request and returns the data. Right now, i'm trying to test the controller, and i'm trying to test that 1) the factory method is called upon loading the controller, and 2) that the controller correctly assigns the returned data through it's callback. For a while I was having trouble getting a mocked factory to pass a test, but once I did, I realized I wasn't actually testing my controller anymore, but the code below passes. Any tips on how I can still get it to pass with mock, promises/callbacks, but accurately test my controller functionality. Or should I even test the this at all in my controller since it calls a factory method and just gives it a callback? My 3 files are below. Can anyone help here? It would be greatly appreciated
mainController.js
'use strict';
myApp.controller('mainController', [ 'mainFactory', '$scope', '$resource', function(factory, scope, resource){
//hits the /games server route upon page load via the factory to grab the list of video games
scope.games = [];
factory.populateTable(function(data){
scope.games = data;
});
}]);
mainFactory.js
'use strict';
myApp.factory('mainFactory', ['$http', '$routeParams', '$location', function(http, routeParams, location) {
var factory = {};
factory.populateTable = function(callback) {
http.get('/games')
.then(function(response){
callback(response.data);
})
};
return factory;
}]);
And finally my mainController_spec.js file
'use strict';
describe("mainController", function() {
var scope,
ctrl,
deferred,
mainFactoryMock;
var gamesArray = [
{name: 'Mario World', manufacturer: 'Nintendo'},
{name: 'Sonic', manufacturer: 'Sega'}
];
var ngInject = angular.mock.inject;
var ngModule = angular.mock.module;
var setupController = function() {
ngInject( function($rootScope, $controller, $q) {
deferred = $q.defer();
deferred.resolve(gamesArray);
mainFactoryMock = {
populateTable: function() {}
};
spyOn(mainFactoryMock, 'populateTable').and.returnValue(deferred.promise);
scope = $rootScope.$new();
ctrl = $controller('mainController', {
mainFactory: mainFactoryMock,
$scope: scope
});
})
}
beforeEach(ngModule("angularApp"));
beforeEach(function(){
setupController();
});
it('should start with an empty games array and populate the array upon load via a factory method', function(){
expect(scope.games).toEqual([])
mainFactoryMock.populateTable();
expect(mainFactoryMock.populateTable).toHaveBeenCalled();
mainFactoryMock.populateTable().then(function(d) {
scope.games = d;
});
scope.$apply(); // resolve promise
expect(scope.games).toEqual(gamesArray)
})
});
Your code looks "non-standard" e.g still using scope.
If you are just starting with angular I hardly recommend you to read and follow this:
https://github.com/johnpapa/angular-styleguide/blob/master/a1/README.md
Angular controllers cannot be tested, extract the logic into factories/services and test from there.
I have a Service:
angular.module('cfd')
.service('StudentService', [ '$http',
function ($http) {
// get some data via the $http
var path = 'data/people/students.json';
var students = $http.get(path).then(function (resp) {
return resp.data;
});
//save method create a new student if not already exists
//else update the existing object
this.save = function (student) {
if (student.id == null) {
//if this is new student, add it in students array
$scope.students.push(student);
} else {
//for existing student, find this student using id
//and update it.
for (i in students) {
if (students[i].id == student.id) {
students[i] = student;
}
}
}
};
But when I call save(), I don't have access to the $scope, and get ReferenceError: $scope is not defined. So the logical step (for me), is to provide save() with the $scope, and thus I must also provide/inject it to the service. So if I do that like so:
.service('StudentService', [ '$http', '$scope',
function ($http, $scope) {
I get the following error:
Error: [$injector:unpr] Unknown provider: $scopeProvider <- $scope <-
StudentService
The link in the error (wow that is neat!) lets me know it is injector related, and might have to do with order of declaration of the js files. I have tried reordering them in the index.html, but I think it is something more simple, such as the way I am injecting them.
Using Angular-UI and Angular-UI-Router
The $scope that you see being injected into controllers is not some service (like the rest of the injectable stuff), but is a Scope object. Many scope objects can be created (usually prototypically inheriting from a parent scope). The root of all scopes is the $rootScope and you can create a new child-scope using the $new() method of any scope (including the $rootScope).
The purpose of a Scope is to "glue together" the presentation and the business logic of your app. It does not make much sense to pass a $scope into a service.
Services are singleton objects used (among other things) to share data (e.g. among several controllers) and generally encapsulate reusable pieces of code (since they can be injected and offer their "services" in any part of your app that needs them: controllers, directives, filters, other services etc).
I am sure, various approaches would work for you. One is this:
Since the StudentService is in charge of dealing with student data, you can have the StudentService keep an array of students and let it "share" it with whoever might be interested (e.g. your $scope). This makes even more sense, if there are other views/controllers/filters/services that need to have access to that info (if there aren't any right now, don't be surprised if they start popping up soon).
Every time a new student is added (using the service's save() method), the service's own array of students will be updated and every other object sharing that array will get automatically updated as well.
Based on the approach described above, your code could look like this:
angular.
module('cfd', []).
factory('StudentService', ['$http', '$q', function ($http, $q) {
var path = 'data/people/students.json';
var students = [];
// In the real app, instead of just updating the students array
// (which will be probably already done from the controller)
// this method should send the student data to the server and
// wait for a response.
// This method returns a promise to emulate what would happen
// when actually communicating with the server.
var save = function (student) {
if (student.id === null) {
students.push(student);
} else {
for (var i = 0; i < students.length; i++) {
if (students[i].id === student.id) {
students[i] = student;
break;
}
}
}
return $q.resolve(student);
};
// Populate the students array with students from the server.
$http.get(path).then(function (response) {
response.data.forEach(function (student) {
students.push(student);
});
});
return {
students: students,
save: save
};
}]).
controller('someCtrl', ['$scope', 'StudentService',
function ($scope, StudentService) {
$scope.students = StudentService.students;
$scope.saveStudent = function (student) {
// Do some $scope-specific stuff...
// Do the actual saving using the StudentService.
// Once the operation is completed, the $scope's `students`
// array will be automatically updated, since it references
// the StudentService's `students` array.
StudentService.save(student).then(function () {
// Do some more $scope-specific stuff,
// e.g. show a notification.
}, function (err) {
// Handle the error.
});
};
}
]);
One thing you should be careful about when using this approach is to never re-assign the service's array, because then any other components (e.g. scopes) will be still referencing the original array and your app will break.
E.g. to clear the array in StudentService:
/* DON'T DO THAT */
var clear = function () { students = []; }
/* DO THIS INSTEAD */
var clear = function () { students.splice(0, students.length); }
See, also, this short demo.
LITTLE UPDATE:
A few words to avoid the confusion that may arise while talking about using a service, but not creating it with the service() function.
Quoting the docs on $provide:
An Angular service is a singleton object created by a service factory. These service factories are functions which, in turn, are created by a service provider. The service providers are constructor functions. When instantiated they must contain a property called $get, which holds the service factory function.
[...]
...the $provide service has additional helper methods to register services without specifying a provider:
provider(provider) - registers a service provider with the $injector
constant(obj) - registers a value/object that can be accessed by providers and services.
value(obj) - registers a value/object that can only be accessed by services, not providers.
factory(fn) - registers a service factory function, fn, that will be wrapped in a service provider object, whose $get property will contain the given factory function.
service(class) - registers a constructor function, class that will be wrapped in a service provider object, whose $get property will instantiate a new object using the given constructor function.
Basically, what it says is that every Angular service is registered using $provide.provider(), but there are "shortcut" methods for simpler services (two of which are service() and factory()).
It all "boils down" to a service, so it doesn't make much difference which method you use (as long as the requirements for your service can be covered by that method).
BTW, provider vs service vs factory is one of the most confusing concepts for Angular new-comers, but fortunately there are plenty of resources (here on SO) to make things easier. (Just search around.)
(I hope that clears it up - let me know if it doesn't.)
Instead of trying to modify the $scope within the service, you can implement a $watch within your controller to watch a property on your service for changes and then update a property on the $scope. Here is an example you might try in a controller:
angular.module('cfd')
.controller('MyController', ['$scope', 'StudentService', function ($scope, StudentService) {
$scope.students = null;
(function () {
$scope.$watch(function () {
return StudentService.students;
}, function (newVal, oldVal) {
if ( newValue !== oldValue ) {
$scope.students = newVal;
}
});
}());
}]);
One thing to note is that within your service, in order for the students property to be visible, it needs to be on the Service object or this like so:
this.students = $http.get(path).then(function (resp) {
return resp.data;
});
Well (a long one) ... if you insist to have $scope access inside a service, you can:
Create a getter/setter service
ngapp.factory('Scopes', function (){
var mem = {};
return {
store: function (key, value) { mem[key] = value; },
get: function (key) { return mem[key]; }
};
});
Inject it and store the controller scope in it
ngapp.controller('myCtrl', ['$scope', 'Scopes', function($scope, Scopes) {
Scopes.store('myCtrl', $scope);
}]);
Now, get the scope inside another service
ngapp.factory('getRoute', ['Scopes', '$http', function(Scopes, $http){
// there you are
var $scope = Scopes.get('myCtrl');
}]);
Services are singletons, and it is not logical for a scope to be injected in service (which is case indeed, you cannot inject scope in service). You can pass scope as a parameter, but that is also a bad design choice, because you would have scope being edited in multiple places, making it hard for debugging. Code for dealing with scope variables should go in controller, and service calls go to the service.
You could make your service completely unaware of the scope, but in your controller allow the scope to be updated asynchronously.
The problem you're having is because you're unaware that http calls are made asynchronously, which means you don't get a value immediately as you might. For instance,
var students = $http.get(path).then(function (resp) {
return resp.data;
}); // then() returns a promise object, not resp.data
There's a simple way to get around this and it's to supply a callback function.
.service('StudentService', [ '$http',
function ($http) {
// get some data via the $http
var path = '/students';
//save method create a new student if not already exists
//else update the existing object
this.save = function (student, doneCallback) {
$http.post(
path,
{
params: {
student: student
}
}
)
.then(function (resp) {
doneCallback(resp.data); // when the async http call is done, execute the callback
});
}
.controller('StudentSaveController', ['$scope', 'StudentService', function ($scope, StudentService) {
$scope.saveUser = function (user) {
StudentService.save(user, function (data) {
$scope.message = data; // I'm assuming data is a string error returned from your REST API
})
}
}]);
The form:
<div class="form-message">{{message}}</div>
<div ng-controller="StudentSaveController">
<form novalidate class="simple-form">
Name: <input type="text" ng-model="user.name" /><br />
E-mail: <input type="email" ng-model="user.email" /><br />
Gender: <input type="radio" ng-model="user.gender" value="male" />male
<input type="radio" ng-model="user.gender" value="female" />female<br />
<input type="button" ng-click="reset()" value="Reset" />
<input type="submit" ng-click="saveUser(user)" value="Save" />
</form>
</div>
This removed some of your business logic for brevity and I haven't actually tested the code, but something like this would work. The main concept is passing a callback from the controller to the service which gets called later in the future. If you're familiar with NodeJS this is the same concept.
Got into the same predicament. I ended up with the following. So here I am not injecting the scope object into the factory, but setting the $scope in the controller itself using the concept of promise returned by $http service.
(function () {
getDataFactory = function ($http)
{
return {
callWebApi: function (reqData)
{
var dataTemp = {
Page: 1, Take: 10,
PropName: 'Id', SortOrder: 'Asc'
};
return $http({
method: 'GET',
url: '/api/PatientCategoryApi/PatCat',
params: dataTemp, // Parameters to pass to external service
headers: { 'Content-Type': 'application/Json' }
})
}
}
}
patientCategoryController = function ($scope, getDataFactory) {
alert('Hare');
var promise = getDataFactory.callWebApi('someDataToPass');
promise.then(
function successCallback(response) {
alert(JSON.stringify(response.data));
// Set this response data to scope to use it in UI
$scope.gridOptions.data = response.data.Collection;
}, function errorCallback(response) {
alert('Some problem while fetching data!!');
});
}
patientCategoryController.$inject = ['$scope', 'getDataFactory'];
getDataFactory.$inject = ['$http'];
angular.module('demoApp', []);
angular.module('demoApp').controller('patientCategoryController', patientCategoryController);
angular.module('demoApp').factory('getDataFactory', getDataFactory);
}());
Code for dealing with scope variables should go in controller, and service calls go to the service.
You can inject $rootScope for the purpose of using $rootScope.$broadcast and $rootScope.$on.
Otherwise avoid injecting $rootScope. See
Common Pitfalls: $rootScope exists, but it can be used for evil.
I have an Angular application where in I'm pulling from a model some data which is saved on the load of the app. For simplicity sake, I've explicitly defined the data which is being pulled.
The issue I have is that in one of my controllers I am running a function on load of the controller which modifies the data pulled from the model. The point is that I want that extra data for that page which is using that controller only. I don't want that data to be saved back into the model (which is what's happening).
My model:
'use strict';
(function () {
var PotsMod = function ($log, _) {
return {
pots: [
{"comp" : "comp1"},
{"comp" : "comp2"}
],
getPots: function () {
return this.pots;
},
};
};
angular
.module('picksApp.models')
.factory('PotsMod', PotsMod);
})();
My controller:
(function () {
function AdmCtrl($log, $routeParams, PotsMod) {
var vm = this;
vm.pots = PotsMod.getPots();
vm.init = function() {
// populate pot.competition
_.forEach(vm.pots, function(pot) {
pot.comp = "test";
});
console.log(PotsMod.getPots());
}
vm.init();
}
angular
.module('picksApp.controllers')
.controller('AdmCtrl', AdmCtrl);
})();
The final line in vm.init(), PotsMod.getPots(), returns to me the updated model, with the values of "comp" as test.
So I tried this instead - I put the debug line under vm.pots like so:
var vm = this;
vm.pots = PotsMod.getPots();
console.log(vm.pots);
vm.init = function() {....
This also returns to me the array where the object values are test...
So I tried one final thing and added an extra debug line in the vm.init() function too:
var vm = this;
vm.pots = PotsMod.getPots();
console.log(vm.pots);
vm.init = function() {
// populate pot.competition
_.forEach(vm.pots, function(pot) {
console.log(pot.comp);
pot.comp = "test";
});
console.log(PotsMod.getPots());
}
vm.init();
The result of this confuses me... The output in the console reads:
[{"comp":"test"},{"comp","test"}]
comp1
comp2
[{"comp":"test"},{"comp","test"}]
I must be missing something here because I don't understand how it can be defining a variable using a model's value, printing that variable with the updated values, then using the old values and printing them, then printing the updated values again from the model (even though nothing in this code touches the model).
Any help would be brilliant please, I see to be making a fundamental mistake somewhere. Thank you.
You're referencing the service's pots object in your controller, so your controller code is also modifying the service's code.
I created a Plunker to demonstrate how angular.copy() creates a deep copy of your service's 'pots', and thus your controller's model is no longer referencing the original.
In your case, all you need to change is vm.pots = angular.copy(getPots());
http://plnkr.co/edit/jg5mWIWds1KMJd51e3o5?p=preview
Hitting the ceiling of my Angular knowledge and I have been going around in circles on this.
Basically I have video player and chapter list directives, each with a controller. The controllers use the same model service which looks like this:
.service('VideoPlayerModel', function(){
var model = this;
model.chapters = {
chapterPos: 0,
targetChapter:null,
data: []
},
model.getVideoData = function() {
return model.videoData;
};
model.setVideoData = function(vData){
...
...
...
};
});
In the video player controller as the time of the player updates it finds the needed chapter data and updates the model.chapters data like this:
updateChapter: function(currentTime){
var chapters = VideoPlayerModel.chapters;
var chaptersCtrl = videoPlayerCtrl.chapters;
if (chapters.nextChapter.start <= currentTime) {
chapters.chapterPos = chapters.chapterPos + 1;
chaptersCtrl.setChapter(); //This finds and sets the Target Chapter
}
},
After setChapter runs I call console.log(VideoPlayerModel.chapters) and I can see the data model has updated with a result like this:
Object {chapterPos: 1, targetChapter: Object, data: Array[6], nextChapter: Object}
However the watch in the ChapterListCtrl doesn't fire and any of the onscreen items displaying the ChapterPos still show just the initial val of 0.
The controller looks like this:
.controller("ChapterListCtrl", ['$scope', 'VideoPlayerModel', function($scope, VideoPlayerModel) {
$scope.chapters = VideoPlayerModel.chapters;
$scope.$watch(function() { return VideoPlayerModel.chapters; }, function(newValue, oldValue){
$scope.chapters = newValue;
console.log("A Change"); // Only runs at initialisation.
});
}])
I have tried different ways and ended up with this, not sure if I am in the complete wrong direction now. Can anyone please help?
You don't need to use $watch, $broadcast or $on. This is best solved by regular JavaScript thinking.
Your problem is $scope.chapters = newValue; That is where you break the binding that your controllers use by introducing a new object unrelated to your service.
What you should to instead is to think about your service model.chapters = {..} and say hey! This is THE ONE object that I will use. And if I want to change the data in this object anywhere, I will switch the data inside the object and NOT assign a new object to the reference I use.
To do this I use the following methods:
transferDataList = function (from, to) {
/*
http://stackoverflow.com/questions/1232040/empty-an-array-in-javascript
*/
to.length = 0;
for (var i = 0; i < from.length; i++) { to.push(from[i]); }
};
transferDataMap = function (from, to) {
/*
http://stackoverflow.com/questions/684575/how-to-quickly-clear-a-javascript-object
*/
var member;
for (member in to) { delete to[member]; }
for (member in from) { to[member] = from[member]; }
};
And when I want to change the data in my object I DON'T do:
$scope.chapters = newValue;
Instead I do:
transferDataMap(newValue, $scope.chapters);
Or:
transferDataList(newValue, $scope.chapters);
This way you will keep your binding and your Angular interfaces will always be updated.
You can use $broadcast() and $on() function to achieve your requirement.
$broadcast() will flush an event to all it's child controller. So, you can $broadcast() an event with your new value to all controllers when you set a new value to your shared model.
Add a broadcast method in your shared service.
model.setVideoData = function(vData){
UpdateYourModel();
// Inform that your model is updated
$rootScope.$broadcast('modelUpdated');
}
And now you can add a listener for the event modelUpdated in all your controllers.
$scope.$on('modelUpdated', function () {
$scope.controllerModel = VideoPlayerModel.getVideoData(); // Update your controller model
}
And also, inject $rootScope to your service,
.service("VideoPlayerModel", ["$rootScope", function($rootScope){
// define your service here.
}] );
That's all !!!
I hope this will help you.
Try changing your watcher to:
$scope.$watch('chapters', function(newValue, oldValue){
$scope.chapters = newValue;
console.log("A Change"); // Only runs at initialisation.
});
Alternatively if that doesn't achieve what you want, you can enable a deep watch by passing the third argument:
$scope.$watch('chapters', function(newValue, oldValue){
$scope.chapters = newValue;
console.log("A Change"); // Only runs at initialisation.
}, true);
Your watcher doesn't fire because it always returns the same chapters which Angular considers as not-changed because it checks by reference. Your watcher can also be refactored as:
$scope.$watch(function() { return VideoPlayerModel.chapters.length; }, function(newValue, oldValue){
$scope.chapters = newValue;
console.log("A Change"); // Only runs at initialisation.
});
I'm using a factory to poll a particular web service. This web service is used to update data any the factory. I initiate this factory in the main controller, and populate a scope variable through a factory function. The variable initializes correctly, and I get the right data on the screen, but I'm struggling on getting the data to bind automatically.
Edit for additional notes:
The reason this code is in a Factory is that I plan on using the factory data across multiple views.
Here is what I have so far:
App.factory('metrics', function($http, $q, $timeout){
var service;
var users = [{laps:[]}];
var updateMetrics = function(){
//updates the users array in the factory
};
service.load = function (){
var deferred = $q.defer();
$http.get('http://www.example.com/api/random').success(function(data) {
var temp_array = data.split("\n");
updateMetrics(0, temp_array);
deferred.resolve({status: 'good'});
$timeout(service.load,3000);
});
return deferred.promise;
};
service.lastLapInfo = function(){
var lastlap = [];
for (var i=0; i<users.length;i++)
{
var lap = users[i].laps[users[i].laps.length-1];
lastlap.push(lap);
}
return lastlap;
};
return service;
});
App.controller('mainController', function($scope, metrics) {
metrics.load().then(function(response){
$scope.$watch(function () { return metrics.lastLapInfo() }, function (newVal, oldVal) {
if (newVal !=oldVal)
{
$scope.users=metrics.lastLapInfo();
}
});
});
});
When I try the above, I get an error saying '10 $digest() iterations reached'. I don't see how that's possible, asI'm not calling the watch function multiple times.
Any suggestions (or other means to accomplish what I'm trying to do?)
If you're not 100% set on using $watch, a pattern that I prefer is to bind new instances of (not references to) modules to the current scope and keep the controllers strictly as components used for wiring together the project's views and models. This excludes the use of $watch, even for coordinating data across modules. I prefer to use $rootScope's $broadcast, $emit and $on methods within modules/factories (after passing in $rootScope as a service, which may or may not work for all situations, though it has for all that I've come across) rather than the comparatively sluggish $watch or $watchCollection methods. Using the latter makes me feel dirty inside... But I digress.
Would something like the following work in your situation?
App.factory('metrics', function($http, $q, $timeout){
var service;
service.users = [{laps:[]}];
service.updateMetrics = function(){
// updates the users array in the current instance of `metrics`
// ex:
// this.users = updatedMetrics;
// don't do:
// service.users = updatedMetrics;
};
service.load = function (){
var deferred = $q.defer();
$http.get('http://www.example.com/api/random').success(function(data) {
var temp_array = data.split("\n");
this.updateMetrics(0, temp_array);
deferred.resolve({status: 'good'});
$timeout(service.load,3000);
}.bind(this));
return deferred.promise;
};
service.lastLapInfo = function(){
var lastlap = [];
for (var i=0; i<this.users.length;i++)
{
var lap = this.users[i].laps[this.users[i].laps.length-1];
lastlap.push(lap);
}
return lastlap;
};
return service;
});
App.controller('mainController', function($scope, metrics) {
$scope.metrics = angular.copy(metrics);
$scope.metrics.load();
});
By setting $scope.metrics = angular.copy(metrics), we are creating a new instance of metrics, rather than setting $scope.metrics as a reference to metrics ($scope.metrics = metrics). This has several benefits, including that you can now use multiple instances of the same module in the controller (ie $scope.foo = angular.copy(foo); $scope.bar = angular.copy(foo); since the objects bound to $scope are completely new objects, rather than references to the same module.
Another benefit is that the instance of metrics attached to $scope can be used to call methods on metrics which can allow any changes to metrics to automatically be applied to your controller's views. I frequently faced odd issues when trying to get this to work when not using angular.copy or $.extend, seemingly because changes to the referenced module attached to $scope were not always being registered.