<div ng-repeat="item in CategorizedItems"
ng-if="CategorizedItems.length> 0"
class="row customRow itemBorder animated slideInLeft" >
{{item.name}}
</div>
I show the list of items in above div.
On click of a button, CategorizedItems are updated.
i.e
$scope.CategorySelected=function(categoryName){
$rootScope.CategorizedItems =[];
$rootScope.CategorizedItems = $rootScope.Items.filter(function(obj){
if(obj.category.name === categoryName)
return obj
});
}
This method is called.Now, when I go from one class to another, New items appear gracefully but items from previous category appear under the list of new items for a couple of seconds.
This is a common problem in Angular.
Most people do this ...
<div ng-if="false">
don't display me
</div>
and then at end of HTML ...
<script src=".....angular.min.js">
and expect the DIV to not appear. Of course it will initially appear in this scenario since it has no idea what ng-if means UNTIL angular is loaded.
Put your angular script include at top of page.
You may also wish to consider using ngCloak directive or CSS class, which is the documented way of resolving this issue (assuming script tag is at top of page).
If I have real problems with this then I might use $scope.readyToRender boolean variable in my controller to control when to display elements.
e.g. at end of controller code I would set it to true and wrap code in an ng-if='readyToRender'
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.
Any idea how to get this to work?:
<div ng-repeat="item in editable_values" ng-init="val = edit_data[item]">
From what I can tell, val is always undefined, based on {{val}} not displaying anything. I'm guessing that ng-init is running when editable_values is defined, but I actually need it to run when edit_data changes.
This does work, but feels hacky:
<div ng-repeat="item in editable_values">
<div ng-show="false">{{val = edit_data[item]}}</div>
editable_values is a list of keys
edit_data is an object
editable_values is defined at creation time in the controller, while edit_data isn't defined until the user clicks on something to edit. The div that acts as a container for the ng-repeat in question isn't actually visible until a user clicks on something to edit.
The ng-repeat used to be (item, val) in edit_data, but I needed to sort the keys in a specific order.
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
When I change the path of the page, my ng-view keeps its contents until the new ones are loaded by my routeProvider. Is there a way to hide them immediately and display a spinner till the new ones load?
See this fiddle regarding loading screen (can customize as necessary): http://jsfiddle.net/KmXTy/1/.
I think what you are looking for though is ng-cloak. It hides ng elements until Angular is ready for them.
<div id="template1" ng-cloak>{{ 'hello' }}</div>
<div id="template2" ng-cloak class="ng-cloak">{{ 'hello IE7' }}</div>
See https://docs.angularjs.org/api/ng/directive/ngCloak.
Also, this may be helpful: Angularjs: How to display loading-icon when using 'resolve' in $routeProvider?.
I am trying to do what looks like a simple process: to display a list of items received from an HTTP request with animation.
First of all, here is my way of doing it ( I am open to any suggestions to do it in a better angular way ):
I define a scope variable state that I initialize to loading in my controller and that I change to loaded when I receive data from the HTTP request.
I initialize a scope variable items with the received data.
In my view, I use ng-switch for the states, and ng-repeat with the items.
I define an animation with css on ng-repeat.
Here is a plunkr ( with a $timeout instead of the request ).
I cannot understand why the animation does not work.
Any help will be appreciated. Thanks.
The reason it is happening is because your ng-when. The same thing happens with ng-if, but would work fine if you used ng-show.
The problem is that when your ng-when condition returns true, the ng-when first renders it's content in a detatched dom (so animations do not happen). This dom is then attached to the dom tree (this step is animated but you would have to put your animation class on the ng-when).
When using something like ng-show or ng-hide things work as expected because the dom is always attached (it is simply shown/hidden).
This might be considered either a bug or a limitation of ng-animate, you might want to post a github issue and see if the angular guys have any thoughts.
It seems to be a "feature" of angular that it won't add .ng-enter to repeat items inside ng-switch-when block. You can remove ng-switch-when="loaded" and it will work (You don't really need it as ng-repeat won't do anything if there is no items)
<div ng-switch="state">
<div ng-switch-when="loading">
<p>Please wait...</p>
</div>
<div >
<ul ng-repeat="item in items" class="animate-items">
<li>{{item}}</li>
</ul>
</div>
</div>
http://plnkr.co/edit/ocEj7BSQPSeIdnnfAOIE?p=preview