Thanks in advance for taking the time to look into this question
I have serverside generated code that renders a directive wrapped around pre-rendered content.
<serverside-demo color="blue">
<p><strong>Content from Server, wrapped in a directive.</strong></p>
<p>I want this color to show: <span ng-style="{color: color}">{{color}}</span></p>
<button ng-click="onClickButtonInDirective()">Click Me</button>
</serverside-demo>
This means that 1.) the directive tag, 2.) the content inside the directive tag, 3.)the ng-click and 4.) The curly braces syntax are all generated by the server.
I want AngularJs to pick up the generated code, recompile the template and deal with the scope.
The problem is that I am having trouble getting it working. I understand that because the ng-click is inside the controller block, it is picked up not by the directive isolated scope, but the parent controllers. Instead I want the opposite... to pick up the onClickButtonInDirective scope function inside the serversideDemo link
I have created a jsfiddle best explaining my problem, which aims to clearly demonstrate the working "traditional" way of loading the template separately (which works) comparing it to the server-side way.
https://jsfiddle.net/stevewbrown/beLccjd2/3/
What is the best way to do this?
Thank you!
There are two major problem in your code
1- directive name and dom element not matched, - missing in dom element
app.directive('serverSideDemo', function() {
use <server-side-demo color="blue"> instead of <serverside-demo color="blue">
2- you need to compile the html code of server-side-demo dom with directive scope in link function
$compile(element.contents())(scope);
Working jsfiddle
Use templateUrl instead of template to fetch the content of directive from server:
app.directive('serverSideDemo', function() {
return {
restrict: 'AE',
scope: {
color: '='
},
templateUrl: 'link/that/returns/html/content',
link: function(scope, element, attrs) {
scope.onClickButtonInDirective = function() {
console.log('You clicked the button in the serverside demo')
scope.color = scope.color === 'blue' ? 'red' : 'blue';
}
}
};
});
Have a look at angular docs for more details
I already know what is the purpose of each item in : compile vs link(pre/post) vs controller
So let's say I have this simple code :
HTML
<body ng-controller="mainController">
{{ message }}
<div otc-dynamic=""></div>
</body>
Controller
app.controller("mainController", function($scope) {
$scope.label = "Please click";
$scope.doSomething = function() {
$scope.message = "Clicked!";
};
});
Directive
app.directive("otcDynamic", function($compile) {
var template = "<button ng-click='doSomething()'>{{label}}</button>";
return {
compile: function(tElement, tAttributes) {
angular.element(tElement).append(template);
for (var i = 0; i < 3; i++) {
angular.element(tElement).append("<br>Repeat " + i + " of {{name}}");
}
return function postLink(scope, element, attrs) {
scope.name = "John";
}
}
}
});
So as we can see , I modify the template (at the compile function - which is where it should be actually)
Result ( plnker):
But
I didn't know that template:... can also take a function.
So I could use the template function instead (plunker) :
app.directive("otcDynamic", function() {
var template1 = "<button ng-click='doSomething()'>{{label}}</button>";
return {
template: function(element, attr) {
element.append(template1);
for (var i = 0; i < 3; i++)
element.append("<br>Repeat " + i + " of {{name}}");
},
link: function(scope, element) {
scope.name = "John";
}
}
});
Question
If so - When should I use the template function vs compile function ?
Let me try to explain what I understood so far.
Directives is a mechanism to work with DOM in Angular. It gives you leverage of playing with DOM element and it's attribute. So it also gives you callbacks to make your work easy.
template , compile and link are those examples. Since your question is specific with compile and template I would like to add about link as well.
A) Template
Like it state, it is a bunch of HTML tags or files to represent it on DOM directly as the face of your directive.
Template can be a file with specific path or inline HTML in code. Like you stated above. template can be wrap in function but the sole use of template is the final set of HTML which will be placed on DOM. Since you have the access to element and its attributes, you can perform as many DOM operation here as well.
B) Compile
Compile is a mechanism in directive which compiles the template HTML or DOM to do certain operation on it and return final set of HTML as template. Like given in Angular DOC
Compiles an HTML string or DOM into a template and produces a template function, which can then be used to link scope and the template together.
Which clearly says that, this is something on top of template. Now like I said above you can achieve similar operations in template as well but when we have methods for its sole purpose, you should use them for the sake of best practice.
You can read more here https://docs.angularjs.org/api/ng/service/$compile
C) Link
Link is used to register listeners like $watch, $apply etc to link your template with Angular scope so that it will get binded with module. When you place any directive inside controller, the flow of scope goes through the link that means the scope is directly accessible in link. Scope is sole of angular app and thus it gives you advantage of working with actual model. Link is also useful in dom manipulations and can be used to work with any DOM element using jQlite
So collecting all above in one
1. Template is the primary source of DOM or HTML to directive. it can be a file or inline HTML.
2. Compile is the wrapper to compile HTML into final template. It is used to gather all the HTML element and attribute to create template for directive.
3. Link is the listener wrapper for various scope and watchers. It binds scope of current controller with html of template and also do manipulation around it.
Hope this helps a bit to understand. Thanks
I have a custom attribute directive (i.e., restrict: "A") and I want to pass two expressions (using {{...}}) into the directive as attributes. I want to pass these attributes into the directive's template, which I use to render two nested div tags -- the outer one containing ng-controller and the inner containing ng-include. The ng-controller will define the controller exclusively used for the template, and the ng-include will render the template's HTML.
An example showing the relevant snippets is below.
HTML:
<div ng-controller="appController">
<custom-directive ctrl="templateController" tmpl="template.html"></custom-directive>
</div>
JS:
function appController($scope) {
// Main application controller
}
function templateController($scope) {
// Controller (separate from main controller) for exclusive use with template
}
app.directive('customDirective', function() {
return {
restrict: 'A',
scope: {
ctrl: '#',
tmpl: '#'
},
// This will work, but not what I want
// Assigning controller explicitly
template: '<div ng-controller="templateController">\
<div ng-include="tmpl"></div>\
</div>'
// This is what I want, but won't work
// Assigning controller via isolate scope variable from attribute
/*template: '<div ng-controller="ctrl">\
<div ng-include="tmpl"></div>\
</div>'*/
};
});
It appears that explicitly assigning the controller works. However, I want to assign the controller via an isolate scope variable that I obtain from an attribute located inside my custom directive in the HTML.
I've fleshed out the above example a little more in the Plunker below, which names the relevant directive contentDisplay (instead of customDirective from above). Let me know in the comments if this example needs more commented clarification:
Plunker
Using an explicit controller assignment (uncommented template code), I achieve the desired functionality. However, when trying to assign the controller via an isolate scope variable (commented template code), it no longer works, throwing an error saying 'ctrl' is not a function, got string.
The reason why I want to vary the controller (instead of just throwing all the controllers into one "master controller" as I've done in the Plunker) is because I want to make my code more organized to maintain readability.
The following ideas may be relevant:
Placing the ng-controller tags inside the template instead of wrapping it around ng-include.
Using one-way binding ('&') to execute functions instead of text binding ('#').
Using a link function instead of / in addition to an isolate scope.
Using an element/class directive instead of attribute directive.
The priority level of ng-controller is lower than that of ng-include.
The order in which the directives are compiled / instantiated may not be correct.
While I'm looking for direct solutions to this issue, I'm also willing to accept workarounds that accomplish the same functionality and are relatively simple.
I don't think you can dynamically write a template key using scope, but you certainly do so within the link function. You can imitate that quite succinctly with a series of built-in Angular functions: $http, $controller, $compile, $templateCache.
Plunker
Relevant code:
link: function( scope, element, attrs )
{
$http.get( scope.tmpl, { cache: $templateCache } )
.then( function( response ) {
templateScope = scope.$new();
templateCtrl = $controller( scope.ctrl, { $scope: templateScope } );
element.html( response.data );
element.children().data('$ngControllerController', templateCtrl);
$compile( element.contents() )( templateScope );
});
}
Inspired strongly by this similar answer.
Please see this jsfiddle: http://jsfiddle.net/viro/DK5pC/3/
What I did looks right compared to the tutorials and replies I've found, so I'm sure I'm overlooking something trivial.
I'm trying to do a directive on a html element, that will create a sibling div to display a message associated with the original element.
for example, for this html :
<input ng-model="inp" tst-msg="message" />
I would create as a sibling element:
<div class="msg">Msg:<span ng-bind="tstMsg"></span></div>
I was hoping that tstMsg in the div's scope would be bound to message in the input's scope.
Here's what the directive looks like :
angular.module('tst', [])
.directive('tstMsg', function(){
var template = "<div class='msg' >Msg:<span ng-bind='tstMsg'></span></div>";
var link = function(scope,element,attrs) {
element.parent().append(template);
console.log("link called");
};
return {
restrict: 'A',
scope: {
tstMsg: '='
},
link: link
};
});
Well that doesn't work and I can't figure out why.
You need to $compile the template you're adding to the DOM. Angular hasn't had a chance to add it's handlers, for instance the ng-bind directive to that part of the dom.
So instead of just adding the element like this:
element.parent().append(template);
These steps will let Angular process your template and then add it.
newe = angular.element(template);
$compile(newe)(scope);
element.parent().append(newe);
Updated fiddle
When you create a directive, you can put code into the compiler, the link function or the controller.
In the docs, they explain that:
compile and link function are used in different phases of the angular
cycle
controllers are shared between directives
However, for me it is not clear, which kind of code should go where.
E.g.: Can I create functions in compile and have them attached to the scope in link or only attach functions to the scope in the controller?
How are controllers shared between directives, if each directive can have its own controller? Are the controllers really shared or is it just the scope properties?
Compile :
This is the phase where Angular actually compiles your directive. This compile function is called just once for each references to the given directive. For example, say you are using the ng-repeat directive. ng-repeat will have to look up the element it is attached to, extract the html fragment that it is attached to and create a template function.
If you have used HandleBars, underscore templates or equivalent, its like compiling their templates to extract out a template function. To this template function you pass data and the return value of that function is the html with the data in the right places.
The compilation phase is that step in Angular which returns the template function. This template function in angular is called the linking function.
Linking phase :
The linking phase is where you attach the data ( $scope ) to the linking function and it should return you the linked html. Since the directive also specifies where this html goes or what it changes, it is already good to go. This is the function where you want to make changes to the linked html, i.e the html that already has the data attached to it. In angular if you write code in the linking function its generally the post-link function (by default). It is kind of a callback that gets called after the linking function has linked the data with the template.
Controller :
The controller is a place where you put in some directive specific logic. This logic can go into the linking function as well, but then you would have to put that logic on the scope to make it "shareable". The problem with that is that you would then be corrupting the scope with your directives stuff which is not really something that is expected.
So what is the alternative if two Directives want to talk to each other / co-operate with each other? Ofcourse you could put all that logic into a service and then make both these directives depend on that service but that just brings in one more dependency. The alternative is to provide a Controller for this scope ( usually isolate scope ? ) and then this controller is injected into another directive when that directive "requires" the other one. See tabs and panes on the first page of angularjs.org for an example.
I wanted to add also what the O'Reily AngularJS book by the Google Team has to say:
Controller - Create a controller which publishes an API for communicating across directives. A good example is Directive to Directive Communication
Link - Programmatically modify resulting DOM element instances, add event listeners, and set up data binding.
Compile - Programmatically modify the DOM template for features across copies of a directive, as when used in ng-repeat. Your compile function can also return link functions to modify the resulting element instances.
A directive allows you to extend the HTML vocabulary in a declarative fashion for building web components. The ng-app attribute is a directive, so is ng-controller and all of the ng- prefixed attributes. Directives can be attributes, tags or even class names, comments.
How directives are born (compilation and instantiation)
Compile: We’ll use the compile function to both manipulate the DOM before it’s rendered and return a link function (that will handle the linking for us). This also is the place to put any methods that need to be shared around with all of the instances of this directive.
link: We’ll use the link function to register all listeners on a specific DOM element (that’s cloned from the template) and set up our bindings to the page.
If set in the compile() function they would only have been set once (which is often what you want). If set in the link() function they would be set every time the HTML element is bound to data in the
object.
<div ng-repeat="i in [0,1,2]">
<simple>
<div>Inner content</div>
</simple>
</div>
app.directive("simple", function(){
return {
restrict: "EA",
transclude:true,
template:"<div>{{label}}<div ng-transclude></div></div>",
compile: function(element, attributes){
return {
pre: function(scope, element, attributes, controller, transcludeFn){
},
post: function(scope, element, attributes, controller, transcludeFn){
}
}
},
controller: function($scope){
}
};
});
Compile function returns the pre and post link function. In the pre link function we have the instance template and also the scope from the controller, but yet the template is not bound to scope and still don't have transcluded content.
Post link function is where post link is the last function to execute. Now the transclusion is complete, the template is linked to a scope, and the view will update with data bound values after the next digest cycle. The link option is just a shortcut to setting up a post-link function.
controller: The directive controller can be passed to another directive linking/compiling phase. It can be injected into other directices as a mean to use in inter-directive communication.
You have to specify the name of the directive to be required – It should be bound to same element or its parent. The name can be prefixed with:
? – Will not raise any error if a mentioned directive does not exist.
^ – Will look for the directive on parent elements, if not available on the same element.
Use square bracket [‘directive1′, ‘directive2′, ‘directive3′] to require multiple directives controller.
var app = angular.module('app', []);
app.controller('MainCtrl', function($scope, $element) {
});
app.directive('parentDirective', function() {
return {
restrict: 'E',
template: '<child-directive></child-directive>',
controller: function($scope, $element){
this.variable = "Hi Vinothbabu"
}
}
});
app.directive('childDirective', function() {
return {
restrict: 'E',
template: '<h1>I am child</h1>',
replace: true,
require: '^parentDirective',
link: function($scope, $element, attr, parentDirectCtrl){
//you now have access to parentDirectCtrl.variable
}
}
});
Also, a good reason to use a controller vs. link function (since they both have access to the scope, element, and attrs) is because you can pass in any available service or dependency into a controller (and in any order), whereas you cannot do that with the link function. Notice the different signatures:
controller: function($scope, $exceptionHandler, $attr, $element, $parse, $myOtherService, someCrazyDependency) {...
vs.
link: function(scope, element, attrs) {... //no services allowed
this is a good sample for understand directive phases
http://codepen.io/anon/pen/oXMdBQ?editors=101
var app = angular.module('myapp', [])
app.directive('slngStylePrelink', function() {
return {
scope: {
drctvName: '#'
},
controller: function($scope) {
console.log('controller for ', $scope.drctvName);
},
compile: function(element, attr) {
console.log("compile for ", attr.name)
return {
post: function($scope, element, attr) {
console.log('post link for ', attr.name)
},
pre: function($scope, element, attr) {
$scope.element = element;
console.log('pre link for ', attr.name)
// from angular.js 1.4.1
function ngStyleWatchAction(newStyles, oldStyles) {
if (oldStyles && (newStyles !== oldStyles)) {
forEach(oldStyles, function(val, style) {
element.css(style, '');
});
}
if (newStyles) element.css(newStyles);
}
$scope.$watch(attr.slngStylePrelink, ngStyleWatchAction, true);
// Run immediately, because the watcher's first run is async
ngStyleWatchAction($scope.$eval(attr.slngStylePrelink));
}
};
}
};
});
html
<body ng-app="myapp">
<div slng-style-prelink="{height:'500px'}" drctv-name='parent' style="border:1px solid" name="parent">
<div slng-style-prelink="{height:'50%'}" drctv-name='child' style="border:1px solid red" name='child'>
</div>
</div>
</body>
compile: used when we need to modify directive template, like add new expression, append another directive inside this directive
controller: used when we need to share/reuse $scope data
link: it is a function which used when we need to attach event handler or to manipulate DOM.