Is it possible to Angularjs ng-switch does not re render view? - javascript

In some page of my site, i have some directives inside ng-switch, like this:
<div ng-switch="contentMenuObj.model">
<div ng-switch-when="calendar">
// Some directive
</div>
<div ng-switch-when="history">
// Some directive
</div>
</div>
Every time that I change the "view" (calendar to history) and go back (history to calendar) the angular re-render the calendar view and new queries are make in the server.
My question is about this behavior, is it possible to angular does not re-render the views? If impossible, what is the best way to solve this problem?

If I understand correctly. You would like to not rerender view when contentMenuObj.model change - right? If so apply one way binding
<div ng-switch="::contentMenuObj.model">
<div ng-switch-when="calendar">
// Some directive
</div>
<div ng-switch-when="history">
// Some directive
</div>
</div>
Model in that case will be loaded only once.
Or try to use ng-show / ng-hide directives if you would like to load directives only once.
<div ng-show="contentMenuObj.model == 'calendar'">
// Some directive
</div>
<div ng-show="contentMenuObj.model == 'history'">
// Some directive
</div>

Angular re-render your directives because ng-switch remove div when ng-switch-when condition is not satisfied, which makes directive is destroy and next time must be re-render.
The ng-show directive in contrast to ng-switch directive not remove element, but only hides.
So, if you want to hide and show content without re-rendering, try:
<div>
<div ng-show="contentMenuObj.model === 'calendar'">
// Some directive
</div>
<div ng-show="contentMenuObj.model === 'history'">
// Some directive
</div>
</div>

Related

ng-if inside ng-repeat not working as expected

I have a repeater that I'm using to return views into an accordion. I'd like to conditionally load the views, so I'm wanting to add an ng-if condition on the repeaters elements to check and see if current == true but it's not working. I'm using Angular 1.0.8.
I have a fiddle
<div data-ng-view></div> is showing all the same view
Edit:
Angular 1.0.8 does not support ng-if so I went with the switch statement.
<div ng-switch="group.current">
<div ng-switch-when="true">
<div data-ng-view></div>
</div>
</div>
Problem was at
<div ng-if="group.current == 'true'"><div data-ng-view></div></div>
replaced with
<div ng-if="group.current === true"><div data-ng-view></div></div>
check updated at http://jsfiddle.net/rajumjib/GUwSh/15/

Is it possible to access a function in a directive from a view?

I'm fairly new to AngularJS and trying to learn by doing.
There is a function in a directive I'm looking to access from the view. What I have in my HTML file is
<div collapse class="collapsed" ng-click="toggle()" ></div>
What's going on there is the toggle() function should be called on click and change the class to expanded, effectively changing the background image described in the CSS. toggle() is inside the collapse directive.
It doesn't seem to be accessing it though and I'm not sure why. Is there another way to do this or actually access said directive from the view? Could you explain why it's not accessing it?
Could this question possibly help? 15672709, it leads to this fiddle and goes beyond in case you nest your directives like below:
<div ng-controller="MyCtrl">
<div screen>
<div component>
<div widget>
<button ng-click="widgetIt()">Woo Hoo</button>
</div>
</div>
</div>
</div>

Angularjs Directive -> child directive variables with transclusion

I'm making a complex view with a parent directive, and some sub-directives nested in. I've run into a problem where it seems like variables aren't being passed through the layers of directives properly.
Here's the setup:
<header>
<div expandable expand="functionFromHeader">
<div votable show-vote="variableFromHeader">
...
<!-- from votable template -->
<vote>
<!-- from vote template -->
<div class="vote" ng-show="showVote">vote</div>
</vote>
</div>
</div>
<div class="contentGettingExpanded" ng-show="variableFromHeader">
...
</div>
</header>
Both the expandable directive and the votable directive use transclusion.
The function from the header scope "functionFromHeader" toggles the variable "variableFromHeader".
The problem is the variable starts out false, but the votes show up anyway. (In the link function I inspected it an it is coming through as a string "variableFromHeader" rather than the value of the variable.
The content that is supposed to expand and collapse, starts collapsed as it should, but once it is expanded, it doesn't collapse. The content just flashes on the screen.
How do I properly pass the variables through the directives?

How to expand DIVs the "angular way" (using angular masonry)

I'm trying to expand a DIV element on my angular layout. I'm using angular-masonry to give a mason-style to my layout, but now I need to expand those boxes on click. I've tried a lot of stuff, but it kept overlapping my others elements. Soon figured out that I'll have to write it the "angular way" so I don't run into DOM manipulation conflicts.
Here's my code:
<div class="row" masonry>
<div
class="masonry-brick item-component col-sm-4 col-md-4"
ng-repeat="component in components.components | filter : components.filterByFilter | filter : searchText"
ng-click=" // expand #expandable // "
>
<div class="component-wrapper">
<div class="component">
<img ng-src="#{{ component.thumb }}"/>
</div>
<div class="component">
#{{ component.name_en }}
</div>
</div>
<div id="expandable" class="expand-me codes-wrapper">
<p>XXX</p>
<p>YYY</p>
<p>ZZZ</p>
</div>
</div>
</div>
Here's what I want to accomplish in the "angular way": http://codepen.io/desandro/pen/daKBo
In your example (http://codepen.io/desandro/pen/daKBo) if you click on an element there are two things that will be done:
(1) the style of the clicked item is changed
(2) the function masonry is called on the container element that keeps the divs.
I can't see such a function in angular-masonry pre builded. So i'll guess you have to do this by your self. Here are some hints how to solve this (i havn't try it in real)
Bind a function to ng-click. In this function set a state to the current component. This state shoud be used to toggle the css-class of the element. you can use ng-class for this.
The second part is little bit more complex. I would suggest write a direcive 'masonry-change-listener' and bind it to the element that is bound to the same element with the directive masonry. If you click on a component $emit an event, that something has changed. In the directive 'masonry-change-listener' listen to this event. if this event fires you have to call $element.masonry.apply($element) in the link function.

Conditional logic in AngularJS template

I have an angular template which looks like this...
<div ng-repeat="message in data.messages" ng-class="message.type">
<div class="info">
<div class="type"></div>
<div class="from">From Avatar</div>
<div class="createdBy">Created By Avatar</div>
<div class="arrowTo">
<div class="arrow"></div>
<div class="to">To Avatar</div>
</div>
<div class="date">
<div class="day">25</div>
<div class="month">Dec</div>
</div>
</div>
<div class="main">
<div class="content">
<div class="heading2">{{message.title}}</div>
<div ng-bind-html="message.content"></div>
</div>
</div>
<br />
<hr />
<br />
</div>
I have set up a JSfiddle to show the data being bound.
What I need to do is make the "from", "to" and "arrowTo" divs show conditionally, depending on the content of the data.
The log is is this...
If there is a "from" object in the data then show the "from" div and bind the data but don't show the "createdBy" div .
If there is no "from" object but there is a "createdBy" object then show the "createdBy" div and bind the data.
If there is a "to" object in the data then show the "arrowTo" div and bind it's data.
Or in plain English, if there is a from address, show it, otherwise show who created the record instead and if there is a to address then show that too.
I have looked into using ng-switch but I think I'd have to add extra markup which would leave an empty div if there was no data. Plus I'd need to nest switch directives and I'm not sure if that would work.
Any ideas?
UPDATE:
If I were to write my own directive (If I knew how!) then here is some pseudo code to show how I would want to use it...
<div ng-if="showFrom()">
From Template Goes Here
</div>
<div ng-if="showCreatedBy()">
CreatedBy Template Goes Here
</div>
<div ng-if="showTo()">
To Template Goes Here
</div>
Each of these would disappear if the function/expression evaluated to false.
Angular 1.1.5 introduced the ng-if directive. That's the best solution for this particular problem. If you are using an older version of Angular, consider using angular-ui's ui-if directive.
If you arrived here looking for answers to the general question of "conditional logic in templates" also consider:
1.1.5 also introduced a ternary operator
ng-switch can be used to conditionally add/remove elements from the DOM
see also How do I conditionally apply CSS styles in AngularJS?
Original answer:
Here is a not-so-great "ng-if" directive:
myApp.directive('ngIf', function() {
return {
link: function(scope, element, attrs) {
if(scope.$eval(attrs.ngIf)) {
// remove '<div ng-if...></div>'
element.replaceWith(element.children())
} else {
element.replaceWith(' ')
}
}
}
});
that allows for this HTML syntax:
<div ng-repeat="message in data.messages" ng-class="message.type">
<hr>
<div ng-if="showFrom(message)">
<div>From: {{message.from.name}}</div>
</div>
<div ng-if="showCreatedBy(message)">
<div>Created by: {{message.createdBy.name}}</div>
</div>
<div ng-if="showTo(message)">
<div>To: {{message.to.name}}</div>
</div>
</div>
Fiddle.
replaceWith() is used to remove unneeded content from the DOM.
Also, as I mentioned on Google+, ng-style can probably be used to conditionally load background images, should you want to use ng-show instead of a custom directive. (For the benefit of other readers, Jon stated on Google+: "both methods use ng-show which I'm trying to avoid because it uses display:none and leaves extra markup in the DOM. This is a particular problem in this scenario because the hidden element will have a background image which will still be loaded in most browsers."). See also How do I conditionally apply CSS styles in AngularJS?
The angular-ui ui-if directive watches for changes to the if condition/expression. Mine doesn't. So, while my simple implementation will update the view correctly if the model changes such that it only affects the template output, it won't update the view correctly if the condition/expression answer changes.
E.g., if the value of a from.name changes in the model, the view will update. But if you delete $scope.data.messages[0].from, the from name will be removed from the view, but the template will not be removed from the view because the if-condition/expression is not being watched.
You could use the ngSwitch directive:
<div ng-switch on="selection" >
<div ng-switch-when="settings">Settings Div</div>
<span ng-switch-when="home">Home Span</span>
<span ng-switch-default>default</span>
</div>
If you don't want the DOM to be loaded with empty divs, you need to create your custom directive using $http to load the (sub)templates and $compile to inject it in the DOM when a certain condition has reached.
This is just an (untested) example. It can and should be optimized:
HTML:
<conditional-template ng-model="element" template-url1="path/to/partial1" template-url2="path/to/partial2"></div>
Directive:
app.directive('conditionalTemplate', function($http, $compile) {
return {
restrict: 'E',
require: '^ngModel',
link: function(sope, element, attrs, ctrl) {
// get template with $http
// check model via ctrl.$viewValue
// compile with $compile
// replace element with element.replaceWith()
}
};
});
You can use ng-show on every div element in the loop. Is this what you've wanted: http://jsfiddle.net/pGwRu/2/ ?
<div class="from" ng-show="message.from">From: {{message.from.name}}</div>

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