Develop Reference

scope variable undefined in directive link function

I have a directive which has this piece of code:
return {
restrict: "E",
scope: {
moduleProgress: "=",
modules: "=",
parentScroll: "="
},
templateUrl: 'app/program/module.list.template.html',
link: function(scope,el,attrs,ctrl,tf) {
$templateRequest("app/program/chapter.list.template.html").then(function(template) {
var template = angular.element(template);
var elements = [];
console.log(scope);
attrs.$observe("modules", function(val) {
scope.modules.forEach(function(module) {
module.open = false;
});
});
For some reason, the first time I navigate to the view that contains this directive everything works fine, but from the second time onwards I always get a Cannot call method 'forEach' of undefined error. I read through some similar questions on SO which mentioned interpolated attributes not being instantly available on the link function, so they reccomended the use of $observe. I even added a console.log(scope) and the modules property shows up on the object. Any idea of what might be causing this?

It should be rather $scope.$watch rather that attrs.$observe as $observe required # in isolated scope of directive & on html it would be modules="{{module}}", For big object DOM will get messed up so I'd prefer you to use $watch which make sense
Code
scope.$watch("modules", function(newVal) {
if(newVal){
scope.modules.forEach(function(module) {
module.open = false;
});
}
});

passing defined object to another custom directive angularjs

so I have this custom directives that you could see below.
myApp.directive('myDirective', function (testService) {
return {
restrict:'EA',
link:function (scope, element, attr) {
//defined the object
var object = new object();
testService.setObject(object);
}
}
});
myApp.directive('mySecondDirective', function (testService) {
return {
restrict:'EA',
link:function (scope, element, attr) {
//call the variable from previous custom directive
console.log(testService.getobject()); -> always return undefined
}
}
});
and this is the html structure where I used the directives above.
<my-directive></my-directive>
<my-second-directive></my-second-directive>
there I want to retreive the object that contains new object() from previous custom directive, but it always return an undefined I wonder how could I do this without using require nor isolated scope as well.. could you guys help me ?
UPDATE
I create a service to provide the facility to set and retreive the object and apparently it returned undefined because I set the custom direcitve this way
<my-second-directive></my-second-directive>
<my-directive></my-directive>
and this is the service
define(
['services/services'],
function(services)
{
'use strict';
services.factory('testService', [function() {
var me = this;
var testObject = '';
return {
setObject: function(object) {
me.testObject = object;
},
getObject: function() {
return me.testObject;
}
}
}
]);
}
);
the thing is that I actually set the html markup like I already mentioned above which is
<my-second-directive></my-second-directive>
<my-directive></my-directive>
so could you give me some advice on how should I do this ?
note* that the passing object actually worked I prefer using services because it will easy to mantain latter. The question is how do I make the object accessible from another directive even though the initiate install of the object (set the object) in the directive that I defined at the html markup, as the last position of the html it self ?
UPDATE this is the PLUNKER that I've been made for you to understand the question it self

You could achieve this by firing a custom event and then listening for it in the second directive. Here's an updated plunker: http://plnkr.co/edit/512gi6mfepyc04JKfiep?p=info
Broadcast the event from the first directive:
app.directive('myDirective', function(testService) {
return {
restrict: 'EA',
link: function(scope, elm, attr) {
var object = {};
testService.setObject(object);
console.log('setting object');
scope.$broadcast('objectSet');
}
}
});
... and then listen for it on the second:
app.directive('mySecondDirective', function(testService) {
return {
restrict: 'EA',
link: function(scope, elm, attr) {
scope.$on('objectSet', function(){
console.log('retrieving object', testService.getObject());
})
}
}
});
You could also pass data along with the event, if you wanted to emit a specific piece of data to be picked up by the second directive.

1). Scope. Since you don't want to use controllers and isolated scope, then you can simply set this object as scope property.
myApp.directive('myDirective', function() {
return {
restrict: 'EA',
link: function(scope, element, attr) {
var object = {};
object.test = 21;
// set object as scope property
scope.object = object;
}
}
});
myApp.directive('mySecondDirective', function() {
return {
priority: 1, // priority is important here
restrict: 'EA',
link: function(scope, element, attr) {
console.log('Retrieve: ', scope.object);
}
}
});
Just make sure you are also defining priority on the second directive (only if both directive a applied to the same element) to make sure it's evaluated in proper turn (should be bigger then the one of myDirective, if omitted it's 0).
2). Service. Another simple solution is to use service. You can inject custom service into both directives and use it storage for you shared object.

Expanding from what #gmartellino said.
Anything that you wanted to do after listening to the event in second directive, can have a callBack method and use it.
app.directive('mySecondDirective', function(testService) {
return {
restrict: 'EA',
link: function(scope, elm, attr) {
// what if I created like this ?
// define the test variable
var test;
scope.$on('objectSet', function(){
//set the variable
test = testService.getObject();
console.log('retrieving object : ', testService.getObject());
//Anything that you wanted to do
//after listening to the event
//Write a callBack method and call it
codeToExecuteAsCallBack();
})
//then use this method to make a call back from the event
//and outside the event too.
var codeToExecuteAsCallBack = function(){
console.log(test);
}
codeToExecuteAsCallBack();
}
}
});
Updated plnkr link

Angular where to place $watch

I have a promise object from which my page gets data something like:
promise.then(function (data) {
$scope.myData = data;
});
and outside of the then callback I have watches on objects on the page. If I am going to watch some piece of data that my promise provides, should I always place my #watches inside of the then callback of the promise?

When you $watch an object, it's really just registering a subscription to changes of the existing object. It won't run until a change is registered, so having it inside the resolve of a promise isn't necessary.

I would have thought in principle you would only want to setup your $watch once after you have declared the variable receiving the data. Without seeing the code it's difficult to be certain but I would expect problems if I set a $watch each time a promise returned.
The callback function of the $watch is passed both the old and new value so you can inspect the values to determine watch action to take.

You should retrieve your data from a service:
app.factory('myService', function($http) {
var someData = [];
return {
getData: function() {
var promise = $http({method:'GET', url:'/api/someurl' });
promise.success(function(data) {
angular.copy(data, someData);
});
return promise;
},
data: someData
}
});
And then assign the data to your scope inside your controller
app.controller('ctrl', function($scope, myService) {
$scope.data = myService.data;
});
Consume the data within your HTML, or from inside your directive
<body ng-app="app">
<ul>
<li ng-repeat="item in data">{{ item }}</li>
</ul>
<my-directive model="data"></my-directive>
</body>
If you do go with a custom directive, it is recommended to setup your $watch inside your directive's link function:
app.directive('myDirective', function() {
return {
restrict: 'E',
link: function(scope, elem, attr) {
scope.$watch('data', function(newVal) {
...
});
}
}
});
There is no reason for $watch handlers to be inside the callback of a promise. It should remain separate so that there is a clean separation between how the data is retrieved from the service and how the data is consumed from the view.

Angular JS: How do I set a property on directive local scope that i can use in the template?

I want to access a variable in this case map in the directive without having to predefine it like setting it as an attr of the directrive map="someValue". And also i dont want to use scope.$apply because i actually only want the variable in the isolated scope of the directive. Is this even possible ?
What is the best practice here? Basically my directive needs to do both. Access the parent scope and have its own scope which with i can build the template with.
Thank you everybody.
Here my Js code:
.directive('myFilter', function() {
return {
restrict: 'E',
scope: {
source: '=source',
key: '=key',
},
link: function(scope, element, attrs) {
scope.$on('dataLoaded', function(e) {
scope.map = {};
angular.forEach(scope.source, function(paramObj) {
if (!scope.map[paramObj[scope.key]]) {
var newEntry = {
value: paramObj[scope.key],
isChecked: false
}
scope.map[paramObj[scope.key]] = newEntry;
}
});
});
}
}
});
and my html:
<my-filter source="metaPara.filteredParameters" key="'value'">
<table class="table table-borered">
<tr data-ng-repeat="item in map">
<td>{{item.value}}</td>
</tr>
</table>
</my-filter>

You might want to refer to the Angular documentation for directives, again.
If you want an isolate-scope (a scope which has no access to ancestors), then use
scope : { /* ... */ }
otherwise, if you want a unique scope, which does have access to ancestors, use
scope : true
Then, you can put your HTML-modifying or event-listening (that doesn't rely on ng-click or something else Angular already covers) in
link : function (scope, el, attrs, controller) { }
...and you can put all of your regular implementation inside of
controller : ["$scope", function ($scope) {
var myController = this;
myController.property = "12";
}],
controllerAs : "myController"
So that in your template you can say:
<span>{{ myController.property }}</span>
You can also use a pre-registered controller, which you call by name:
controller : "mySimpleController",
controllerAs : "myController"
Also, rather than using $scope.$apply, I'd recommend using $timeout (has to be injected).
The difference is that $scope.$apply will only work at certain points -- if you're already inside of a digest cycle, it will throw an error, and not update anything.
$timeout( ) sets the updates to happen during the next update-cycle.
Ideally, you should know whether or not you need an $apply or not, and be able to guarantee that you're only using it in one spot, per update/digest, but $timeout will save you from those points where you aren't necessarily sure.

Callback function inside directive attr defined in different attr

So I have this directive called say, mySave, it's pretty much just this
app.directive('mySave', function($http) {
return function(scope, element, attrs) {
element.bind("click", function() {
$http.post('/save', scope.data).success(returnedData) {
// callback defined on my utils service here
// user defined callback here, from my-save-callback perhaps?
}
});
}
});
the element itself looks like this
<button my-save my-save-callback="callbackFunctionInController()">save</button>
callbackFunctionInController is for now just
$scope.callbackFunctionInController = function() {
alert("callback");
}
when I console.log() attrs.mySaveCallback inside my-save directive, it just gives me a string callbackFunctionInController(), I read somewhere that I should $parse this and it would be fine, so I tried to $parse(attrs.mySaveCallback) which gave me back some function, but hardly the one I was looking for, it gave me back
function (a,b){return m(a,b)}
What am I doing wrong? Is this approach flawed from the beginning?

So what seems like the best way is using the isolated scope as suggested by ProLoser
app.directive('mySave', function($http) {
return {
scope: {
callback: '&mySaveCallback'
}
link: function(scope, element, attrs) {
element.on("click", function() {
$http.post('/save', scope.$parent.data).success(returnedData) {
// callback defined on my utils service here
scope.callback(); // fires alert
}
});
}
}
});
For passing parameters back to controller do this
[11:28] <revolunet> you have to send named parameters
[11:28] <revolunet> eg my-attr="callback(a, b)"
[11:29] <revolunet> in the directive: scope.callback({a:xxx, b:yyy})

There are a lot of ways to go about what you're doing. The FIRST thing you should know is that the $http.post() is going to be called as soon as that DOM element is rendered out by the template engine, and that's it. If you put it inside a repeat, the call will be done for each new item in the repeater, so my guess is this is definitely not what you want. And if it is then you really aren't designing things correctly because the existence of DOM alone should not dictate queries to the backend.
Anyway, directly answering your question; if you read the albeit crappy docs on $parse, it returns you an evaluation expression. When you execute this function by passing the scope to evaluate on, the current state of that expression on the scope you passed will be returned, this means your function will be executed.
var expression = $parse(attrs.mySave);
results = expression($scope); // call on demand when needed
expression.assign($scope, 'newValu'); // the major reason to leverage $parse, setting vals
Yes, it's a little confusing at first, but you must understand that a $scope changes constantly in asynchronous apps and it's all about WHEN you want the value determined, not just how. $parse is more useful for a reference to a model that you want to be able to assign a value to, not just read from.
Of course, you may want to read up on creating an isolate scope or on how to $eval() an expression.
$scope.$eval(attrs.mySave);

You can use .$eval to execute a statement in the given scope
app.directive('mySave', function($http) {
return function(scope, element, attrs) {
$http.post('/save', scope.data).success(returnedData) {
// callback defined on my utils service here
// user defined callback here, from my-save-callback perhaps?
scope.$eval(attrs.mySaveCallback)
}
}
});
TD: Demo
If you want to share data between a directive and a controller you can use the two way binding
app.controller('AppController', function ($scope) {
$scope.callbackFunctionInController = function() {
console.log('do something')
};
$scope.$watch('somedata', function(data) {
console.log('controller', data);
}, true);
});
app.directive('mySave', function($http, $parse) {
return {
scope: {
data: '=mySaveData',
callback: '&mySaveCallback' //the callback
},
link: function(scope, element, attrs) {
$http.get('data.json').success(function(data) {
console.log('data', data);
scope.data = data;
scope.callback(); //calling callback, this may not be required
});
}
};
});
Demo: Fiddle

scope: {
callback: '&mySaveCallback'
}
Setting the scope explicitly could be a good solution but if you want the reach other parts of the original scope you can't because you have just overwritten it. For some reason, I needed to reach other parts of the scope too so I used the same implementation as ng-click do.
The use of my directive in HTML:
<div my-data-table my-source="dataSource" refresh="refresh(data)">
Inside the directive (without setting the scope explicitly):
var refreshHandler = $parse(attrs.refresh);
scope.$apply(function () {
refreshHandler( {data : conditions}, scope, { $event: event });
});
With this I can call the function in controller and pass parameters to it.
In the controller:
$scope.refresh= function(data){
console.log(data);
}
And it prints the conditions correctly out.

This worked for me
Inside the view script
<tag mycallbackattrib="scopemethod">
Inside the directive
$scope[attrs.mycallbackattrib](params....);
It is correctly called and params are passed, but maybe is not a best 'angular way' to work.

You should be using ng-click instead of creating your own directive.

app.directive('mySave', function($http, $parse) {
return {
scope: {
data: '=mySaveData',
callback: '&' //the callback
},
link: function(scope, element, attrs) {
$http.get('data.json').success(function(data) {
console.log('data', data);
if (scope.callback()) scope.callback().apply(data);
});
}
};
});