I'm implementing an Angular/RequireJS routing solution based on Dan Wahlin's article.
In the article, Dan makes the following register shortcuts on his app object:
app.register =
{
controller: $controllerProvider.register,
directive: $compileProvider.directive,
filter: $filterProvider.register,
factory: $provide.factory,
service: $provide.service
};
When I use these, I can correctly register and reference my controllers through RequireJS calls, but if I use the traditionall app.controller() or angular.module('myApp').controller() syntax, then Angular can't find them and I get errors from the router.
How is defining controllers, directives, etc. with the above method different, and why does it work with RequireJS where the more traditional method does not?
Any ideas?
Thanks,
-Nate
Since the controllers are being added dynamically things have to change a bit from the "norm" (unfortunately). The main difference is that controllers are being wrapped in RequireJS modules, being downloaded dynamically, and then being registered. The $controllerProvider.register allows for the dynamic registration. It's definitely not the normal technique but what's required in this scenario. That's why "app" (which is the RequireJS module that gets us to the application's AngularJS module) is passed in to all of the controller modules. It exposes the controller property shown above which handles the registration "on the fly".
If you download a controller script dynamically and then use the normal technique (angular.module('..').controller(..)) it won't register it properly - at least that was the case the last time I tried it. It's been several months since I've tried it but I'm assuming the same behavior is still there.
The bottom line is that when controllers (and other items such as services/factories) have scripts that are loaded "on the fly" things change somewhat and the way you access and register these items changes from the normal way that we're all used to seeing.
Related
There are two ways (AFAIK) to associate a controller with a view template/partial: the route specified in $routeProvider and the ngController directive. Especially (but not exclusively) for simple routing, is there any benefit/efficiency of one over the other?
My project currently uses the $routeProvider approach, but I've been given the task of nesting views. This seems simple enough with ngInclude, as long as the partial specifies its ngController.
This question really comes down to design and as such it is a bit opinion based. That in mind, the best guidance I know is:
$routeProvider - Allows you to specify a single controller for a template. Since this is part of the routing it makes it easy to find the controller that goes with the page. I use this to store and load overall page logic rather than element specific logic.
This is also important because it means you can load the exact same template for two different routes but the behavior and data could be different because the controller can be changed. This is not something that is easy to do with the ngController option.
ngController - This scopes the controller to a specific element on the page/template. That can make the code easier to read when you need multiple controllers on a single page and it allows the controller to be more specifically scoped.
So it really comes down to scope and intent. Hopefully these rules will help when deciding which to use.
If you think of a view including all scripts as a self-contained package, developed by a single person or team, then ngController is the way to go, imho.
$routeProvider on the other hand provides you with advanced features like injection of values via the resolve property of the route. That way you can have your AJAX loaded data directly injected into your controller, e.g., instead of the controller having it to get itself. Or have the route change to wait for that data etc.
Btw: If you need routing and nested views you can take a look at angular ui-router
Thanks to the great article from Dan Wahlin, I managed to implement lazy loading of Angular's controllers and services. However, there does not seem to be a clean way to lazy load independent modules.
To better explain my question, assume that I have an app would be structure as below without RequireJS:
// Create independent module 'dataServices' module with 'Pictures' object
angular.module("dataServices", []).factory("Pictures", function (...) {...});
// Create 'webapp' ng-app, with dependency to 'dataServices', defining controllers
angular.module("webapp", ['dataServices'])
.controller("View1Controller", function (...) {...})
.controller("View2Controller", function (...) {...});
Here is the sample app with RequireJS in Plunker:
http://plnkr.co/aiarzVpMJchYPjFRrkwn
The core of the problem is that Angular does not allow adding dependency to ng-app post instantiation. As result, my solution is to use angular.injector to retrieve the instance of Picture object to be used in my View2Controller. See js/scripts/controllers/ctrl2.js file.
This creates 2 problems for me:
The injected services runs outside of angular and therefore all async call must end with $scope.$apply()
Messy code where some object can be injected using standard angular syntax while others require the explicit use of injector.
Have any of you figured out how to lazy load independent module using RequireJS and somehow hook this module in angular so normal angular dependency injection syntax can be used?
Note:
The question is on lazy loading of independent module. One simple solution to this specific example is to create "Pictures" object using cached $providers during ng-app.config but that is not what I am looking for. I am looking for solution that works with 3rd party module such as angular-resource.
I finalized my own implementation called angularAMD and here is the sample site that uses it:
http://marcoslin.github.io/angularAMD/
It handles config functions and out of order module definitions.
Hopefully this can help other looking for something to help them with RequireJS and AngularJS integration.
Take a look at my project in GitHub: angular-require-lazy
This project is intended to demonstrate an idea and motivate discussions. But is does what you want (check expenses-view.js, it loads ng-grid lazily).
I am very interested in comments, ideas etc.
(EDIT) The ng-grid Angular module is lazy loaded as follows:
expenses-view.js is loaded lazily, when the /expenses route is activated
expenses-view.js specifies ng-grid as a dependency, so RequireJs loads ng-grid first
ng-grid is the one that calls angular.module(...)
In order to accomplish this, I replaced (proxied actually) the real angular.module method with my own, that supports laziness. See bootstrap.js and route-config.js (the functions initLazyModules() and callRunBlocks()).
This implementation has its drawbacks that you should be aware of:
Config functions are not implemented (yet). I do not know if it is possible to lazily provide config-time dependencies.
Order matters in definitions. If service A depends on B but A is defined after B in your module, DI wil fail. This is because the lazyAngular proxy executes definitions immediately, unlike real Angular that makes sure dependencies are resolved before executing the definitions.
It looks like the Node.js module ocLazyLoad defines a way of doing this lazy-loading, though I'm not sure how it fares, performance-wise, compared to the methods in the other answers or hard-coding the dependencies. Any info on this would be appreciated. One interesting thing is that the other answers need RequireJS to operate, while ocLazyLoad doesn't.
It looks like ocLazyLoad defines another provider that injects the dependency after the containing module has already been instantiated. It seems to do this by essentially replicating some low-level Angular behavior, like module loading and providing, hence why it looks so complicated. It looks like it adds just about every core Angular module as a dependency: $compileProvider, $q, $injector, ng, and so many more.
I would to dynamically load controller in my partial file so my code is better organized. Through my research, I found that if I want to load controller from partial using the script tag, I need to include JQuery.
However, these approach seem to only work if my controller is declared in the global scope, i.e.
function MainCtrl($scope) {}
If I switch to using module in my controller.js
angular.module ("myApp").controller ("MainCtrl", function ($scope) {});
this no longer work with the error message
"Argument 'MainCtrl' is not a function, got undefined"
Below is a plunker to demonstrate this.
http://plnkr.co/wNv3UD
How could I make this work?
Note
I did not include controller.js in index.html intentionally. I want to load controller from the partial.html, since it would only be used there.
Edit
I was able to achieve what I wanted to to after reading this question: AngularJS Dynamic loading a controller
This seem to be a straightforward approach to support lazy loading. Hopefully the $controllerProvider.register method could be exposed through angular.module.controller in future versions to support lazy loading.
You may want to take a look at [RequireJS][1]
it provides a good and easy way for you to load your .js files on the run.
for the dynamic controller loading part: you should write a provider (a service) which exposes some methods to register your controllers wile the angular app is running (take a look at $controllerProvider in angular docs)
i suggest you take a look at this post as it mentions how to fully customize your application regarding the script loading and controller registeration and stuff like that.
You can achieve this using custom directive and in directive you can load script using jquery getscript or jQuery ajax call, directive will fire when you load the partial
Some of my routes needs functionality from external JS. I don't want to load them all at once since those JS are needed only in certain routes (e.g. /upload needs some JS for photo uploading, /photos needs another JS for lightbox, /funny needs JS for animation stuff, etc).
What's the best practice for lazily loading those external JavaScripts?
Those routes can be accessed multiple times (e.g. user can go to /upload then /photos then /upload again)
In addition to what Alex has stated, if you will be lazy loading AngularJS artefacts such as controllers and directives, you would have to use the relevant provider to register them instead of the module API. Artefacts registered using the module API after the application has been bootstrapped, will not be available to the application. For example, you would define a lazy controller like this...
$controllerProvider.register('SomeLazyController', function($scope)
{
$scope.key = '...';
});
instead of this...
angular.module('app').controller('SomeLazyController', function($scope)
{
$scope.key = '...';
});
I have written a blog post detailing this as well as how to use the 'resolve' method that Alex speaks about, to implement lazy loading in AngularJS. http://ify.io/lazy-loading-in-angularjs/
The only way I know to handle cases like this is using the "resolve" method of a route. This method can be used to define a dependency to be loaded before the route's controller is instantiated. One of the different possible return types of this method is a promise. Thus you might use this to start loading your external JavaScript code asynchronously and return a promise that is resolved as soon as your external scripts are loaded.
The documentation for this can be found here: https://docs.angularjs.org/api/ngRoute/provider/$routeProvider in the "when" section.
#alex3683's answer is probably the correct AngularJS way, but I don't grasp the concept, so instead I make use of jQuery's getScript(). So, in CoffeeScript:
yourModule.factory 'foo', ->
$.getScript 'https://script-to-load', ->
# whatever you want to do once the script is loaded
And just call it from your controller. Since AngularJS services are lazy and singleton, this will only load the script once.
I have been reading a lot of docs, and I'm getting more and more confused.
I basically can't figure out the difference between a
service
directive
module
I see a lot of custom components. Sometimes they're using directives, sometimes services. It always starts with a module. Can someone explain with an example what the difference is between these three types?
From my own personal notes (mostly snippets from the docs, google group posts, and SO posts):
Modules
provide a way to namespace/group services, directives, filters, configuration information and initialization code
help avoid global variables
are used to configure the $injector, allowing the things defined by the module (or the whole module itself) to be injected elsewhere (Dependency Injection stuff)
Angular modules are not related to CommonJS or Require.js. As opposed to AMD or Require.js modules, Angular modules don't try to solve the problem of script load ordering or lazy script fetching. These goals are orthogonal and both module systems can live side by side and fulfill their goals (so the docs claim).
Services
are singletons, so there is only one instance of each service you define. As singletons, they are not affected by scopes, and hence can be accessed by (shared with) multiple views/controllers/directives/other services
You can (and probably should) create custom services when
two or more things need access to the same data (don't use root scope) or you just want to neatly encapsulate your data
you want to encapsulate interactions with, say, a web server (extend $resource or $http in your service)
Built-in services start with '$'.
To use a service, dependency injection is required on the dependent (e.g., on the controller, or another service, or a directive).
Directives (some of the items below say essentially the same thing, but I've found that sometimes a slightly different wording helps a lot)
are responsible for updating the DOM when the state of the model changes
extend HTML vocabulary = teach HTML new tricks. Angular comes with a built in set of directives (e.g., ng-* stuff) which are useful for building web applications but you can add your own such that HTML can be turned into a declarative Domain Specific Language (DSL). E.g., the <tabs> and <pane> elements on the Angular home page demo "Creating Components".
Non-obvious built-in directives (because they don't start with "ng"): a, form, input, script, select, textarea. Under Angular, these all do more than normal!
Directives allow you to "componentize HTML". Directives are often better than ng-include. E.g., when you start writing lots of HTML with mainly data-binding, refactor that HTML into (reusable) directives.
The Angular compiler allows you to attach behavior to any HTML element or attribute and even create new HTML elements or attributes with custom behavior. Angular calls these behavior extensions directives.
When you boil it all down, a directive is just a function which executes when the Angular compiler encounters it in the DOM.
A directive is a behavior or DOM transformation which is triggered by a presence of an attribute, an element name, a class name, or a name in a comment. Directive is a behavior which should be triggered when specific HTML constructs are encountered in the (HTML) compilation process. The directives can be placed in element names, attributes, class names, as well as comments.
Most directives are restricted to attribute only. E.g., DoubleClick only uses custom attribute directives.
see also What is an angularjs directive?
Define and group Angular things (dependency injection stuff) in modules.
Share data and wrap web server interaction in services.
Extend HTML and do DOM manipulation in directives.
And make Controllers as "thin" as possible.
Think of a module as being a place to wire up a number of other things, such as directives, services, constants etc. Modules can be injected into other modules giving you a high level of reuse.
When writing an angular app, you would have a top-level module which is your application code (without templates).
Services are mainly a way to communicate between controllers, but you can inject one service into another. Services are often used as a way to get to your data stores and people will wrap the angular APIs, such as ngResource. This technique is useful since it makes testing (particularly mocking) quite easy. You can have services for doing other things like authentication, logging etc.
Directives are used for creating widgets or wrapping existing things like jquery plugins. Wrapping existing plugins can be a challenge and the reason you would do this is to establish a two-way data binding between the plugins and angular. If you don't need two-way data binding then you don't need to wrap them.
A directive is also a place for doing DOM manipulation, catching DOM-events etc. You should not be doing DOM-related stuff in controllers or services. Creating directives can get pretty complex. IMHO, I recommend first looking at API for something that can do what you are looking for OR ask Angular's Google Group for advice.