get rid of controllers in angular 1.5.x start using component directives
TRANSCRIPT
Get rid of controllers in AngularJS 1.5.x
Start using component directives
Fakiolas Marios - [email protected] / @fakiolinhoFrontend Developer at mist.io, creator of angularjs-recipes.com
What are component directives in AngularJS 1.5 ?
As of AngularJS 1.5.x release a new type of directives was introduced. These are component directives.
A component directive is a component with directives flavor.
This is a huge step which brings us closer to components logic even in AngularJS 1.5.x
We can now build an AngularJS 1.5.x application by replacing controllers with components.
So we can prepare even better our old applications for their upgrade to Angular 2 and its components ways.
Let’s create a simple component directive
// Create it
angular
.module('myApp')
.component('userGreeting', {
bindings: {
user: '='
},
controller: function() {
var self = this;
self.welcome = 'Welcome ' + self.user.name + '!';
},
template: '<h1>{{$ctrl.welcome}}</h1>'
});
// Use it
<user-greeting user="{name: 'John Doe'}"></user-greeting>
<user-greeting user="{name: 'Jane Doe'}"></user-greeting>
Analyze a simple component directive
name
This is the name of the component and the only required option. We should pick wisely a camel-case name to register our component and then call it into action using this. Be careful because it always maps to a dash-case component:
angular
.module('myApp')
.component('userGreeting', {
...
});
<user-greeting user="{name: 'John Doe'}"></user-greeting>
Analyze a simple component directive
bindings
This an optional parameter and it is the way to define DOM attribute binding to component properties. Component properties are always bound to the component controller.
angular
.module('myApp')
.component('userGreeting', {
bindings: {
user: '='
},
...
});
<user-greeting user="{name: 'John Doe'}"></user-greeting>
Analyze a simple component directive
controller
This is an optional parameter and by default an empty function is registered. Here we can use all attributes passed with bindings and run some logic.
angular
.module('myApp')
.component('userGreeting', {
bindings: {
user: '='
},
controller: function() {
var self = this;
self.welcome = 'Welcome ' + self.user.name + '!';
}
...
});
Analyze a simple component directive
template
This is an optional parameter which returns an empty string by default. We can register with it a html template as the content of our component. Check out offered $ctrl as a controller’s alias.
angular
.module('myApp')
.component('userGreeting', {
bindings: {
user: '='
},
controller: function() {
var self = this;
self.welcome = 'Welcome ' + self.user.name + '!';
},
template: '<h1>{{$ctrl.welcome}}</h1>'
});
Analyze a simple component directive
templateUrl
We could use this to call into action an external html file as our component’s template.
angular
.module('myApp')
.component('userGreeting', {
bindings: {
user: '='
},
controller: function() {
var self = this;
self.welcome = 'Welcome ' + self.user.name + '!';
},
templateUrl: 'greeting.html'
});
Are you still ok?
Let’s create a simple Blog application with component directives
https://github.com/Athens-AngularJS-Meetup/blog
Routing with component directives
// Routing using components instead of controllers
angular
.module('myApp')
.config(['$routeProvider', function($routeProvider) {
$routeProvider
.when('/', {
resolve: {
posts: function(Post) {
return Post.all();
}
},
template: '<posts posts="$resolve.posts"></posts>'
})
...
Declaring posts component
// Posts list component
angular
.module('myApp')
.component('posts', {
templateUrl: 'app/templates/posts.html',
bindings: {
posts: '='
},
controller: function() {
var self = this;
self.posts = self.posts.slice(0, 5);
}
});
Declaring posts list and post-item templates
// Posts list template
<section id="posts">
<post-item post="post" ng-repeat="post in $ctrl.posts"></post-item>
</section>
// Post list item template
<div class="post-item card">
<img ng-src="{{$ctrl.img}}" alt="{{$ctrl.post.title}}" />
<div class="card-body">
<h4>{{$ctrl.post.title}}</h4>
<hr>
<p>{{$ctrl.post.body}}</p>
<a ng-href="#/posts/{{$ctrl.post.id}}" class="btn">Read
More</a>
</div>
</div>
Declaring post-item component
// Post item component
angular
.module('myApp')
.component('postItem', {
templateUrl: 'app/templates/post-item.html',
bindings: {
post: '<'
},
controller: function() {
var self = this;
self.img = 'http://lorempixel.com/600/300/city/';
}
});
Declaring Post factory
// Posts factory
angular
.module('myApp')
.factory('Post', ['$http', function($http) {
var service = {
all: all,
get: get
};
return service;
function all() {
return $http
.get('http://jsonplaceholder.typicode.com/posts')
.then(function(data) {
return data.data;
});
}
...
Create even more componentslike social-icons
// Declare the component
angular
.module('myApp')
.component('socialIcons', {
templateUrl: 'app/templates/social-icons.html'
});
// Declare its template
<ul class="social-icons">
<li>
<a href="#"><i class="fa fa-twitter"></i></a>
</li>
...
</ul>
// Use the component
<social-icons></social-icons>
Components data bindings overview
Components bindings type does matter a lot
bindings: {
// Two way data-bindings (avoid usage)
posts: '=',
// One way data-bindings
// Preferable for Objects (highly proposed)
post: '<',
// Preferable for simple Strings
name: '@',
// Outputs data-bindings
onEdit: '&'
}
Components bindings type does matter a lot
Ideally, the whole application should be a tree of components that implement clearly defined inputs and outputs, and minimize two-way data binding. That way, it's easier to predict when data changes and what the state of a component is.
Inputs should be using < and @ bindings. The < symbol denotes one-way bindings (available since 1.5). The difference to = is that the bound properties in the component scope are not watched, which means if you assign a new value to the property in the component scope, it will not update the parent scope.
Components bindings type does matter a lot
Note however, that both parent and component scope reference the same object, so if you are changing object properties or array elements in the component, the parent will still reflect that change. The general rule should therefore be to never change an object or array property in the component scope.
Components cooperation
Of course components have outputs too. These are also declared in bindings and we use them to inform a parent component regarding an edit / delete / update action we want to execute.
Data flow always from parents to children and children never edit their inputs but emit the right callback events backwards to their parents requesting an action.
Outputs are realized with & bindings, which function as callbacks to component events.That way, the parent component can decide what to do with the event (e.g. delete an item or update the properties)
Components cooperation example
// Child's input / output bindings
bindings: {
task: '<',
onDelete: '&'
}
// Child's template
<p>{{$ctrl.post.title}}</p>
<button ng-click="$ctrl.onDelete({post: $ctrl.post})">Delete</button>
//Parent's template
<section id="posts">
<post-item post="post" on-delete="$ctrl.deletePost(post)" ng-repeat="post
in $ctrl.posts"></post-item>
</section>
// Parent's controller
ctrl.deletePost(post) {
...
}
