I have a Vue component that I want to appear sometimes in one spot, sometimes in another. So I give it a property which I test in a v-if directive on the root of template. I have two custom tags in my markup, and assume that I'll get two distinct instances of my component. To my surprise, the component renders twice, even when one of the properties is false. What is going on here?
markup
<div id='vueRoot'>
<now-you-see-me show-me='true'></now-you-see-me>
<now-you-see-me show-me='false'></now-you-see-me>
</div>
js
Vue.component('now-you-see-me',{
template : `<div v-if='showMe'>I only want ONE **{{showMe}}**</div`,
props : ['showMe']
})
vm = new Vue({
el : '#vueRoot'
})
running here
For true and false bindings, you have to use v-bind:show-me instead of just show-me, because the attribute's value will otherwise be evaluated as a string instead of a boolean exprsesion, e.g.:
<now-you-see-me v-bind:show-me='true'></now-you-see-me>
...or if you're more comfortable with shorthands:
<now-you-see-me :show-me='true'></now-you-see-me>
See proof-of-concept below:
Vue.component('now-you-see-me',{
template : `<div v-if='showMe'>I only want ONE **{{showMe}}**</div>`,
props : ['showMe']
})
vm = new Vue({
el : '#vueRoot'
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.4.4/vue.min.js"></script>
<div id='vueRoot'>
<now-you-see-me :show-me='true'></now-you-see-me>
<now-you-see-me :show-me='false'></now-you-see-me>
</div>
You are passing the show-me property as a string, when you actually want to pass it as a boolean. Instead of show-me="..." write v-bind:show-me="..." (or :show-me="..."). Everything inside the " then will be interpreted as Javascript instead of a string.
https://jsfiddle.net/aw3bup8u/1/
Related
I have multiple elements on a page that are triggering a load of select2 to the element. I'm trying to conditionally check if the element has a certain class, and if so add the tag option; otherwise do not. I thought something like this would work, but it's not:
$('.element_to_add_select_two_on').select2({
tags:function(element) {
return (element.className === 'classname_i_am_targeting');
},
});
What am I missing here? I'm subjecting myself to the following buffoonery to get this to target and load:
$('.element_to_add_select_two_on').each((index,element) => {
let showTags = false;
if ($(element).attr('class').split(' ').includes('classname_i_am_targeting')) {
showTags = true;
}
$(element).select2({
tags:showTags,
});
});
There are a few problems with your first attempt. First, you are defining tags as a function when what you want is the result of the function, since tags needs to be defined as a boolean true or false. The other is that inside your .select2() call, you do not have access to the calling element $('.element_to_add_select_two_on') in the way that you think. It isn't an event that you are listening on, it's a function call that wants an object passed with its configuration.
You conveyed that your second method works, but it can be simplified with the jQuery hasClass() function:
$('.element_to_add_select_two_on').each((index, element) => {
$(element).select2({
tags: $(element).hasClass('classname_i_am_targeting'),
});
});
There is a much simpler way to do all of this, however, and it is much more flexible and already built into select2 via the way of data-* attributes (note, you need jQuery > 1.x). You can simply add data-tags="true" to any of your select elements with which you want tags enabled. These will override any configuration options used when initializing select2 as well as any defaults:
<select data-tags="true">
...
</select>
I'm wondering, is there a possibility to have databindings "out of" a template? Say I have a <template/>-Tag somewhere which I put into the slot of a different component - that component stamps it to its context. Then I want to bind data from the root element to the <template/>-Tag. Also, event bindings (on-x-changed) don't work, because you can't assign a function which is defined in the hosting component. Any ideas?
Example:
... host
{{boundData}}
<binding-component>
<template>
{{boundData}}
</template>
</binding-component>
I don't see changes when I observe boundData in the hosting component. Is there a way to get around this? Or is firing a custom event my only chance?
If you are looking for binding a property outside of polymer something like from index.html you may bind value with element. an example ; index.html
<dom-bind>
<template>
<binding-component bound-data="{{boundData}}"></binding-component>
</template>
</dom-bind>
<script>
// set a value a string, Number or Object etc.
// Optionally wrap this code into a listener ie;
// window.addEventListener('load', e=> { ...below code ... })
var boundData= document.querySelector('dom-bind');
boundData = {} //
</script>
Now in your binding-component element has a property as boundData
hope its helps or provide more code to understand better.
I've made it work the way dom-if does it, too. Like in dom-if (reference), I'm creating a Templatize-instance which then uses forwardHostProp to handle the "inside"-properties
this.__ctor = Templatize.templatize(template, this, {
mutableData: true,
forwardHostProp(prop, value) {
// handling item updates, item being the only property
// from within the binding component
// everything else is automatically bound by templatize
this.set(prop, value);
this.update(this.item);
},
});
this.__instance = new this.__ctor();
this.root.appendChild(this.__instance.root);
This all happens in connectedCallback.
Because the Templatize-instance is passed this, it's bound to the current context as well.
Good luck!
I have a Methode from an API. It returns a promise which resolves to an $ctrl(?) object. This objects should contain a measurement and will be updated whenever it receive a new data.
getMeasurements.latest(filter) //only a object to filter through all measurements
.then(function (latestMeasurement) {
$ctrl.latestMeasurement = latestMeasurement;
});
My problem is that I don't know how to work with this data or display it in my html file. How does $ctrl work?
Here the documentation of the API
$ctrl is the view model object in your controller. This $ctrl is a name you choose (vm is another most common name), if you check your code you can see the definition as $ctrl = this;, so basically its the this keyword of the controller function.
So now if you are using $ctrl.latestMeasurement = 'someValue', then its like you are adding a property latestMeasurement to controller function.
Now how to use it in HTML?
To access the latestMeasurement property in HTML your code must have <h1>{{$ctrl.latestMeasurement}}</h1> (H1 tag is just an example.)
Here $ctrl is different from what I explained above on controller part. Here $ctrl is the value used for controllerAs property of the controller. But $ctrl is the default value of the controllerAs property, so your code may not have the controllerAs property defined, so Angular will take default value $ctrl in HTML.
This is where most people gets confused. So let me explain,
Assume in your new controller you have declared your this keyword to variable vm, and you set your controllerAs property to myCtrl, i.e;
controllerAs: 'myCtrl' while defining controller properties.
var vm = this; in your controller function.
In this case in js you have to use vm for setting values, and in HTML you have to use myCtrl. For example,
in JS controller function vm.test = 'Hello world';
in HTML <span ng-bind="myCtrl.test"></span>
The result Hello world will be displayed in your page.
Why $ctrl and not $scope?
The view model object model concept is introduced in AngularJS 1.5, it is actually part of migrating to Angular 2 where $scope no longer exsist. So in 1.5 they introduced new approch but did not removed $scope completely.
Hope the answer helped.
For basic Javascript concepts you can see http://javascriptissexy.com/16-javascript-concepts-you-must-know-well/
For more detailed AngularJS $ctrl concept you can see https://johnpapa.net/angularjss-controller-as-and-the-vm-variable/
I suppose you are toking about this.
In this case, the
$ctrl.latestMeasurement
can means:
$ctrl, the controller where you are running this code. You can change it by $scope for example, and get the same result.
latestMeasurement, the variable where you want to store the last value of the measurement.
To explain my point of view let see the code below
<div ng-app="MeasurementApp">
<div ng-controller="MeasurementController">
<h1>{{latestMeasurement2}}</h1>
</div>
</div>
There you can see a simple angularjs app that shows a variable called latestMeasurement2 in a div and its controller called MeasurementController. Then, to display the value let check your code.
angular.module('MeasurementApp', [])
// creating the controller
.controller('MeasurementController', function(c8yMeasurements, $scope) {
// creating the variable and let it empty by now.
$scope.latestMeasurement2 = "";
// Your code
var filter = {
device: 10300,
fragment: 'c8y_Temperature',
series: 'T'
};
var realtime = true;
c8yMeasurements.latest(filter, realtime)
.then(function (latestMeasurement) {
// The latestMeasurement is where the measurement comes
// Here we just assign it into our $scope.latestMeasurement2
$scope.latestMeasurement2 = latestMeasurement;
});
});
As the documentation says
// $scope.latestMeasurement2 will be updated as soon as a new measurement is received.
$scope.latestMeasurement2 = latestMeasurement;
Hope this helps!
I need to know if there is a way to create HTML local variables programmatically.
I am developing a web app where I have an NgFor loop and I want to be able to assign a local variable to each sub element created by the NgFor.
ie :
<div *ngFor="#elt of eltList" >
<span #setLocalVariable(elt.title)></span>
</div>
setLocalVariable(_title : string){
let var = do some stuff to _title;
return var;
}
The exemple above shows you what I am trying to accomplish and obviously does not work.
Is there a way to achieve this ?
Thank you in advance.
Edit:
After seeing the answers I got (and i thank everyone who took the time to read my question and tried to answer it) i'll explain a bit more why i want it that way.
I will be using : loadIntoLocation() from the DynamicComponentLoader.
That function got as a 3rd parameter a string that refers to an anchors (ie : #test in an html element). Thats why i need to create those local variables with a name equal to the one of my elt.title.
I think local variables (defined with the # character) don't apply for your use case.
In fact, when you define a local variable on an HTML element it corresponds to the component if any. When there is no component on the element, the variable refers to the element itself.
Specifying a value for a local variable allows you to select a specific directive associated with the current element. For example:
<input #name="ngForm" ngControl="name" [(ngModel)]="company.name"/>
will set the instance of the ngForm directive associated with the current in the name variable.
So local variables don't target what you want, i.e. setting a value created for the current element of a loop.
If you try to do something like that:
<div *ngFor="#elt of eltList" >
<span #localVariable="elt.title"></span>
{{localVariable}}
</div>
You will have this following error:
Error: Template parse errors:
There is no directive with "exportAs" set to "elt.title" ("
<div *ngFor="#elt of eltList" >
<span [ERROR ->]#localVariable="elt.title"></span>
{{localVariable}}
</div>
"): AppComponent#2:10
Angular2 actually looks for a directive matching the provided name elt.title here)... See this plunkr to reproduce the error: https://plnkr.co/edit/qcMGr9FS7yQD8LbX18uY?p=preview
See this link: http://victorsavkin.com/post/119943127151/angular-2-template-syntax, section "Local variables" for more details.
In addition to the current element of the iteration, ngForm only provides a set of exported values that can be aliased to local variables: index, last, even and odd.
See this link: https://angular.io/docs/ts/latest/api/common/NgFor-directive.html
What you could do is to create a sub component to display elements in the loop. It will accept the current element as parameter and create your "local variable" as attribute of the component. You will be able then to use this attribute in the template of the component so it will be created once per element in the loop. Here is a sample:
#Component({
selector: 'elt',
template: `
<div>{{attr}}</div>
`
})
export class ElementComponent {
#Input() element;
constructor() {
// Your old "localVariable"
this.attr = createAttribute(element.title);
}
createAttribute(_title:string) {
// Do some processing
return somethingFromTitle;
}
}
and the way to use it:
<div *ngFor="#elt of eltList" >
<elt [element]="elt"></elt>
</div>
Edit
After your comment, I think that you try the approach described in this answer. Here are more details: create dynamic anchorName/Components with ComponentResolver and ngFor in Angular2.
Hope it helps you,
Thierry
You could stick it into the template interpolation since it handles expressions.
<div *ngFor="#elt of eltList" >
<span>{{setLocalVariable(#elt)}}</span>
</div>
setLocalVariable(_title : string){
let var = do some stuff to _title;
return var;
}
I'm trying to use $sanitize provider and the ng-bind-htm-unsafe directive to allow my controller to inject HTML into a DIV.
However, I can't get it to work.
<div ng-bind-html-unsafe="{{preview_data.preview.embed.html}}"></div>
I discovered that it is because it was removed from AngularJS (thanks).
But without ng-bind-html-unsafe, I get this error:
http://errors.angularjs.org/undefined/$sce/unsafe
Instead of declaring a function in your scope, as suggested by Alex, you can convert it to a simple filter :
angular.module('myApp')
.filter('to_trusted', ['$sce', function($sce){
return function(text) {
return $sce.trustAsHtml(text);
};
}]);
Then you can use it like this :
<div ng-bind-html="preview_data.preview.embed.html | to_trusted"></div>
And here is a working example : http://jsfiddle.net/leeroy/6j4Lg/1/
You indicated that you're using Angular 1.2.0... as one of the other comments indicated, ng-bind-html-unsafe has been deprecated.
Instead, you'll want to do something like this:
<div ng-bind-html="preview_data.preview.embed.htmlSafe"></div>
In your controller, inject the $sce service, and mark the HTML as "trusted":
myApp.controller('myCtrl', ['$scope', '$sce', function($scope, $sce) {
// ...
$scope.preview_data.preview.embed.htmlSafe =
$sce.trustAsHtml(preview_data.preview.embed.html);
}
Note that you'll want to be using 1.2.0-rc3 or newer. (They fixed a bug in rc3 that prevented "watchers" from working properly on trusted HTML.)
You need to make sure that sanitize.js is loaded. For example, load it from https://ajax.googleapis.com/ajax/libs/angularjs/[LAST_VERSION]/angular-sanitize.min.js
you need to include ngSanitize module on your app
eg: var app = angular.module('myApp', ['ngSanitize']);
you just need to bind with ng-bind-html the original html content. No need to do anything else in your controller. The parsing and conversion is automatically done by the ngBindHtml directive. (Read the How does it work section on this: $sce). So, in your case <div ng-bind-html="preview_data.preview.embed.html"></div> would do the work.
For me, the simplest and most flexible solution is:
<div ng-bind-html="to_trusted(preview_data.preview.embed.html)"></div>
And add function to your controller:
$scope.to_trusted = function(html_code) {
return $sce.trustAsHtml(html_code);
}
Don't forget add $sce to your controller's initialization.
The best solution to this in my opinion is this:
Create a custom filter which can be in a common.module.js file for example - used through out your app:
var app = angular.module('common.module', []);
// html filter (render text as html)
app.filter('html', ['$sce', function ($sce) {
return function (text) {
return $sce.trustAsHtml(text);
};
}])
Usage:
<span ng-bind-html="yourDataValue | html"></span>
Now - I don't see why the directive ng-bind-html does not trustAsHtml as part of its function - seems a bit daft to me that it doesn't
Anyway - that's the way I do it - 67% of the time, it works ever time.
You can create your own simple unsafe html binding, of course if you use user input it could be a security risk.
App.directive('simpleHtml', function() {
return function(scope, element, attr) {
scope.$watch(attr.simpleHtml, function (value) {
element.html(scope.$eval(attr.simpleHtml));
})
};
})
You do not need to use {{ }} inside of ng-bind-html-unsafe:
<div ng-bind-html-unsafe="preview_data.preview.embed.html"></div>
Here's an example: http://plnkr.co/edit/R7JmGIo4xcJoBc1v4iki?p=preview
The {{ }} operator is essentially just a shorthand for ng-bind, so what you were trying amounts to a binding inside a binding, which doesn't work.
I've had a similar problem. Still couldn't get content from my markdown files hosted on github.
After setting up a whitelist (with added github domain) to the $sceDelegateProvider in app.js it worked like a charm.
Description: Using a whitelist instead of wrapping as trusted if you load content from a different urls.
Docs: $sceDelegateProvider and ngInclude (for fetching, compiling and including external HTML fragment)
Strict Contextual Escaping can be disabled entirely, allowing you to inject html using ng-html-bind. This is an unsafe option, but helpful when testing.
Example from the AngularJS documentation on $sce:
angular.module('myAppWithSceDisabledmyApp', []).config(function($sceProvider) {
// Completely disable SCE. For demonstration purposes only!
// Do not use in new projects.
$sceProvider.enabled(false);
});
Attaching the above config section to your app will allow you inject html into ng-html-bind, but as the doc remarks:
SCE gives you a lot of security benefits for little coding overhead.
It will be much harder to take an SCE disabled application and either
secure it on your own or enable SCE at a later stage. It might make
sense to disable SCE for cases where you have a lot of existing code
that was written before SCE was introduced and you're migrating them a
module at a time.
You can use filter like this
angular.module('app').filter('trustAs', ['$sce',
function($sce) {
return function (input, type) {
if (typeof input === "string") {
return $sce.trustAs(type || 'html', input);
}
console.log("trustAs filter. Error. input isn't a string");
return "";
};
}
]);
usage
<div ng-bind-html="myData | trustAs"></div>
it can be used for other resource types, for example source link for iframes and other types declared here