I have a simple ng-repeat to build a HTML list from a javascript array.
Each item can be moved using an input to get the new rank. This input is binded to a variable rank. This variable is initialized using the ng-init directive.
Code looks like this :
<li ng-repeat="item in ctrl.getItems()">
<div ng-init="rank = $index">
[$index: {{$index}}]
{{item}}<br/>
<label>
Move to
<input type="number" ng-model="rank"/>
</label>
<button type="button" ng-click="ctrl.moveItem($index, rank)">
Ok
</button>
</div>
</li>
At runtime, when I change the input value and click to the Ok button, function ctrl.moveItem is called and item is really moved in the ctrl.getItems() array.
So the ng-repeat is replayded and items appears in the new order.
BUT variable rank is not reinitialized and 2 items appears with the same rank.
The sample is here : https://jsfiddle.net/nlips/4ng34b7b/
My question is not so much about moving items in a list, but I need to understand how ng-init works in the context of ng-repeat.
I did not find anything on this subject in the AngularJS official documentation.
From AngularJS docs:
The ngInit directive allows you to evaluate an expression in the current scope.
Now. You are working with different scope.
You are using ngInit into the transcluded scope, overriding $scope.rank each time it repeats that portion of template.
If you want to persist your rank you should init it into the ngRepeat scope.
Try with:
<li ng-repeat="item in ctrl.getItems()" ng-init="rank = $index">
[$index: {{$index}}]
{{item}}<br/>
<label>
Move to
<input type="number" ng-model="rank"/>
</label>
<button type="button" ng-click="ctrl.moveItem($index, rank)">
Ok
</button>
</li>
EDITED ANSWER
Ok, i got it.
The ngInit expression is evaluated only when that part of template is going to be rendered into the DOM.
So, when the page is loaded for the first time your expression is fired and each rank is evaluated correctly.
But, when you make changes on an item that is already rendered, your template is not going to be rendered again, so your ng-init will not be fired.
If you want that ng-init to be executed again you have to remove the item from the DOM and then append it back, into the new position.
There are several alternatives to this approach, but i hope this clarifies what was going on.
Related
I'm trying to go with the best approach and avoid unnecessary rendering/processing time in my AngularJS app when choosing between 2 directives to be displayed in the page inside an ngRepeat loop, want to know which is the best way:
If by setting the ng-if directly in the directive html element, like:
<div ng-repeat="element in list">
<my-directive-a ng-if="someFunction(element)"></my-directive-a>
<my-directive-b ng-if="!someFunction(element)"></my-directive-b>
</div>
Or by moving out the first <div> from the directive's template and use it as a wrapper for each directive. For instance:
<div ng-repeat="element in list">
<div ng-if="someFunction(element)">
<my-directive-a></my-directive-a>
</div>
<div ng-if="!someFunction(element)">
<my-directive-b></my-directive-b>
</div>
</div>
NOTE: The starting <div> element on each directive could be modified behave the same so I will basically take that out of the directive's html and moving it outside the directive declaration in order to place the ng-if there
What would be the best approach for this case? Are there any performance implications from doing it one way or another? Or is it just the same thing? Consider that the number of elements in the list could get really big.
They are quite the same, but you can improve performance with one-time binding, but only when element does not change at runtime (for example, let's say that it has property name, and your someFunction is like return element.name === 'John'). Angular just stop observing this function when it returns value, and watches will be deleted. There are 2 prerequisites to use this solution:
Elements properties in list does not change (if you rely on them in someFunction), for example if you rely on name property name must not change, because watcher on someFunction is note available.
When list changes or its elements properties change, you reload all list (for example, you fetch it from server again if you know that change occurred)
What you get with this? There is no watches after my-directives are drawn on ng-ifs, and when something changes, new reference is bound to list (for example, it comes from server) and everything will be redrawn, ng-ifs will run again and when will become stable (function returns value) then will be unbound. How it looks like? Like this:
<div ng-repeat="element in list">
<div ng-if="::(someFunction(element))">
<my-directive-a></my-directive-a>
</div>
<div ng-if="::(!someFunction(element))">
<my-directive-b></my-directive-b>
</div>
</div>
Two colons before expression. But be aware, that with one-time binding it's easy to mess up - you need to be sure that you test your code enough to be sure it works.
I have this plunker code.
What I'm trying to do, is to display the gray box one time per row.
To achieve this, I thought to modify the partition filter in order to return a JSON to add it a new property by row to know if the gray box is expanded or not.
But, I could Not successfully return a JSON.
Do you know how to modify the filter to return a JSON or a better way to show the gray box by row?
Related questions:
Push down a series of divs when another div is shown
Update 1
The issue could be easily resolved by using the correct scope for the ng-repeat for the row without modifying the filter, thanks to #m59.
http://plnkr.co/edit/eEMfI1lv6z1MlG7sND6g?p=preview
Update 2
Live Demo
If I try to modify the item, it seems the ng-repeat would be called again losing the props values.
<div ng-repeat="friendRow in friends | partition:2"
ng-init="props = {}">
<div ng-repeat="item in friendRow"
ng-click="collapse(item)"
ng-class="{myArrow: showArrow}">
{{item.name}} {{item.age}} years old.
<div>{{item.name}}</div>
</div>
<div collapse="!props.isExpanded">
some content
<br/>
<input type="text" ng-model="currentItem.name">
</div>
</div>
js
$scope.collapse = function(item){
this.props.isExpanded = !this.props.isExpanded;
this.showArrow = !this.showArrow;
$scope.currentItem = item;
};
This causes the gray box to collapse each time the item is modified. Any clue?
I've updated my code/answer regarding partitioning data. It's important to fully understand all of that before deciding on an approach to your project.
The problem you have in your plnkr demo is that you're modifying the parent $scope and not the scope of the ng-repeat for that row.
Just set a flag on the row and toggle it when clicked:
Live Demo
<div
class="row"
ng-repeat="friendRow in friends | partition:2"
ng-init="isExpanded = false"
ng-click="isExpanded = !isExpanded"
>
<div ng-repeat="item in friendRow">
{{item.name}} {{item.age}} years old.
</div>
<div collapse="!isExpanded">
some content
</div>
</div>
To access the correct scope within a function in the controller, you can use the this keyword instead of $scope. this will refer to the scope the function is called from, whereas $scope refers to the scope attached to the element with ng-controller (a parent of the ng-repeat scopes you want to target).
<div
class="row"
ng-repeat="friendRow in friends | partition:2"
ng-click="collapse()"
>
JS:
$scope.collapse = function() {
this.isExpanded = !this.isExpanded;
};
If you want to keep the ng-click directive on the item element instead of putting it on the row element as I have done, then you're dealing with another child scope because of that inner ng-repeat. Therefore, you will need to follow the "dot" rule so that the child scope can update the parent scope where the collapse directive is. This means you need to nest isExpanded in an object. In this example, I use ng-init="props = {}", and then use props.isExpanded. The dot rule works because the children share the same object reference to props, so the properties are shared rather than just copied, just like in normal JavaScript object references.
Live Demo
<div
class="row"
ng-repeat="friendRow in friends | partition:2"
ng-init="props = {}"
>
<div ng-repeat="item in friendRow" ng-click="collapse()">
{{item.name}} {{item.age}} years old.
</div>
<div collapse="!props.isExpanded">
some content
</div>
</div>
JS:
$scope.collapse = function(){
this.props.isExpanded = !this.props.isExpanded;
};
Update
We keep going through more and more issues with your project. You really just need to experiment/research and understand everything that's going on on a deeper level, or it will just be one question after another. I'll give it one last effort to get you on the right track, but you need to try in the basic concepts and go from there.
You could get past the issue of props reinitializing by putting $scope.expandedStates and then passing the $index of the current ng-repeat to your function (or just using it in the view) and setting a property of expandedStates like $scope.expandedStates[$index] = !$scope.expandedStates[$index]. With the nested ng-repeat as it is, you'll need to do $parent.$index so that you're associating the state with the row rather than the item.
However, you'll then have another problem with the filter: Using my old partition code, the inputs inside the partitions are going to lose focus every time you type a character. Using the new code, the view updates, but the underlying model will not. You could use the partition filter from this answer to solve this, but from my understanding of that code, it could have some unexpected behavior down the road and it also requires passing in this as an argument to the filter. I don't recommend you do this.
Filters are meant to be idempotent, so stabilizing them via some kind of memoization is technically a hack. Some argue you should never do this at all, but I think it's fine. However, you definitely should ONLY do this when it is for display purposes and not for user input! Because you are accepting user input within the partitioned view, I suggest partitioning the data in the controller, then joining it back together either with a watch (continuous) or when you need to submit it.
$scope.partitionedFriends = partitionFilter($scope.friends, 2);
$scope.$watch('partitionedFriends', function(val) {
$scope.friends = [].concat.apply([], val);
}, true); // deep watch
I am running this simple code with angularjs :
HTML :
<div ng-app ng-controller="AController">
<code>{{ itemsInArray }}</code>
<div ng-repeat="item in itemsInArray">
<input ng-model="itemsInArray[$index]" />
</div>
</div>
JavaScript :
function AController($scope) {
$scope.itemsInArray = ["strA", "strB", "strC"];
}
Binding appears to be working correctly when indexing into the array but after entering one character the input loses focus.
You can find the working code here on this fiddle : http://jsfiddle.net/QygW8/
I think this is happening because you are manipulating the same item which is iterated over ng-repeat. So ng-repeat sees a change in the item and re-runs the `ng-repeat which regenerates the items.
If you look at your fiddle html, you may notice this effect.
To make it work, one way you can do this
http://jsfiddle.net/cmyworld/CvLBS/
where you change your array to object array
$scope.itemsInArray = [{data:"strA"}, {data:"strB"}, {data:"strC"}];
and then bind to item.data
Try to change the model:
<div ng-repeat="item in itemsInArray">
<input ng-model="item" />
</div>
Even am an newbie to the angularjs, up-to my findings ng-repeat updates/repeats and recreates the whole HTML elements when there is an change in the model. Hence when a single character added to model causes ng-repeat to react and creates the all the HTML elements again which results to losing the focus.
This is an fiddle , In which u will be able to observer the changes with the model inside the ng-repeat and outside the ng-repeat.
Sorry i don't have the solution, Hope using ng-change apart of ng-model may help.
So i need to know the extras of a car than a user wants to include in his preferences.
I'm trying to create input checkboxes from an array obtained by an ajax request and generate the inputs by ng-repeat. The major objective is to know the checkboxes selected by the user. I'd like that my approach to be create an auxiliar array which contains the selected ones, but i don't know how to set a unique ng-model to every item in the ng-repeat iteration so i can know the list of selected items. I guess there is something left in my knowlege of angular. Here is what i have for now..
In the controller...
$http.get('/ajax/ajax_get_extras/'+$scope.car.version+'/false').success(function(data) {
$scope.extras = data;
});
$scope.addExtra = function(){ // ... manage the auxiliar array }
In the html ...
<div ng-controller="Controller">
<form novalidate class="simple-form">
<span ng-repeat="extra in extras">
<input type="checkbox" ng-model="extra.id" ng-change="addExtra()" name="extra_{{extra.id}}" >{{extra.name}} - <strong>{{extra.real_price | onlynumber | currency}}</strong>
</span>
</form>
</div>
And i'm stuck since the extra.id doesnt transform to the real extra.id and stays as a string "extra.id" >_<
I tried extra_{{extra.id}}, extra.id, {{extra.id}}, $index as posibles ng-model and none works.
In AngularJS 1.1.5 there is "track by" that you can use in ngRepeat.
So you can:
<input type="checkbox" ng-repeat="e in extra track by $index" ng-model="extra[$index]">
Here is a example: http://plnkr.co/edit/6lNo6R5EPsNGHUU6ufTE?p=preview
<input type="text" value="{{codes[0].code}}" ng-click="newNumber(0)" />
<input type="text" value="{{codes[1].code}}" ng-click="newNumber({{codes[1].id}})" />
The first ng-click event fires in my controller just fine but the second one does nothing.
I tried concat'ing as well ... is there some other way I should do this?
ng-click
The value of ng-click is already evaluated as an angular expression. As such, you don't need the {{ }}. Read http://docs.angularjs.org/guide/expression for more information. Take a look at the second example, it will help clarify this.
ng-model
Also, ng-model should be used for data-binding. For example, take a look at this jsfiddle: http://jsfiddle.net/bCpW9/8/ and the notes below.
<li ng-repeat="code in codes">
This loops through the codes collection which was defined in the controller. It creates a <li> for each element in the codes collection.
<input ng-model="codes[$index].code" />
Inside each <li>, an <input> for the current code is created. Each input is bound to it's corresponding element in the codes array by setting ng-model to it. For instance, type a new code into the first input field. It automatically updates the corresponding code model with what you typed, as you can see to the right.
I hope that helps.