I'm looking to update an Angular 1 app to Angular 2 and am having an issue with one of my old directives.
The idea is simple. When an input field is focused a class should be added (md-input-focus) and another be removed (md-input-wrapper). Then this process should be reversed on "blur" event - i.e. focus lost.
My old directive simply included the lines
.directive('mdInput',[
'$timeout',
function ($timeout) {
return {
restrict: 'A',
scope: {
ngModel: '='
},
link: function (scope, elem, attrs) {
var $elem = $(elem);
$elem.on('focus', function() {
$elem.closest('.md-input-wrapper').addClass('md-input-focus')
})
.on('blur', function() {
$(this).closest('.md-input-wrapper').removeClass('md-input-focus');
})
}
etc...
I obviously have the classic start to my directive but have run out of.....skill
import {Directive, ElementRef, Renderer, Input} from 'angular2/core';
#Directive({
selector: '.mdInput',
})
export class MaterialDesignDirective {
constructor(el: ElementRef, renderer: Renderer) {
// Insert inciteful code here to do the above
}
}
Any help would be appreciated.
UPDATE:
The HTML would look like (before the input element was focused):
<div class="md-input-wrapper">
<input type="text" class="md-input">
</div>
and then
<div class="md-input-wrapper md-input-focus">
<input type="text" class="md-input">
</div>
after.
The input element is the only one which can receive a focus event (and therefore the target for the directive) however the parent <div> requires the class addition and removal.
Further help
Please see Plunker for help/explanation - would be great if someone could help
Update
#Directive({selector: '.md-input', host: {
'(focus)': 'setInputFocus(true)',
'(blur)': 'setInputFocus(false)',
}})
class MaterialDesignDirective {
MaterialDesignDirective(private _elementRef: ElementRef, private _renderer: Renderer) {}
setInputFocus(isSet: boolean): void {
this.renderer.setElementClass(this.elementRef.nativeElement.parentElement, 'md-input-focus', isSet);
}
}
Original
This can easily be done without ElementRef and Renderer (what you should strive for in Angular2) by defining host bindings:
import {Directive, ElementRef, Renderer, Input} from 'angular2/core';
#Directive({
selector: '.mdInput',
host: {
'(focus)':'_onFocus()',
'(blur)':'_onBlur()',
'[class.md-input-focus]':'inputFocusClass'
}
})
export class MaterialDesignDirective {
inputFocusClass: bool = false;
_onFocus() {
this.inputFocusClass = true;
}
_onBlur() {
this.inputFocusClass = false;
}
}
or a bit more terse
#Directive({
selector: '.mdInput',
host: {
'(focus)':'_setInputFocus(true)',
'(blur)':'_setInputFocus(false)',
'[class.md-input-focus]':'inputFocusClass'
}
})
export class MaterialDesignDirective {
inputFocusClass: bool = false;
_setInputFocus(isFocus:bool) {
this.inputFocusClass = isFocus;
}
}
I tried it only in Dart where it works fine. I hope I translated it correctly to TS.
Don't forget to add the class to the directives: of the element where you use the directive.
In addition to previous answers, if you don't want to add a directive, for the specific component (you already have a directive for a parent component, you are using Ionic 2 page or something else), you inject the renderer by adding private _renderer: Renderer in the page constructor and update the element using the event target like this:
html:
(dragstart)="dragStart($event)"
TS:
dragStart(ev){
this._renderer.setElementClass(ev.target, "myClass", true)
}
Edit: to remove the class just do:
dragEnd(ev){
this._renderer.setElementClass(ev.target, "myClass", false)
}
The name of the selector has to be inside "[ ]", as shown below
#Directive({
selector: '[.mdInput]',
host: {
'(focus)':'_setInputFocus(true)',
'(blur)':'_setInputFocus(false)',
'[class.md-input-focus]':'inputFocusClass'
}
})
If you want to catch the focus / blur events dynamiclly on every input on your component :
import { AfterViewInit, Component, ElementRef } from '#angular/core';
#Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: [ './app.component.css' ]
})
export class AppComponent implements AfterViewInit {
name = 'Angular focus / blur Events';
constructor(private el: ElementRef) {
}
ngAfterViewInit() {
// document.getElementsByTagName('input') : to gell all Docuement imputs
const inputList = [].slice.call((<HTMLElement>this.el.nativeElement).getElementsByTagName('input'));
inputList.forEach((input: HTMLElement) => {
input.addEventListener('focus', () => {
input.setAttribute('placeholder', 'focused');
});
input.addEventListener('blur', () => {
input.removeAttribute('placeholder');
});
});
}
}
Checkout the full code here : https://stackblitz.com/edit/angular-wtwpjr
Related
in this tutorial
https://www.sitepoint.com/practical-guide-angular-directives/
i am learning how to create a customised directive. i followed the steps as shown in the code posted below, but despite added the exact code as explained in the aforemenrtioned website, when i run the command
ng serve --open
i get something as shown in the image posted below.
please let me know why myCustomIf is not working. i say that myCustomIf is not working because what i got on the localhost:4200 is something as shown in the image posted
please let me know how to make the myCustomIf works as explained in the tutorial in the above posted link
app.component.ts:
import { Component } from '#angular/core';
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'ngDirective1';
name = 'Angular';
condition = false;
}
app.myCustomeIfDirective.ts:
import { Directive, Input, TemplateRef, ViewContainerRef } from '#angular/core';
#Directive({
selector: '[myCustomIf]'
})
export class MyCustomeIfDirective{
constructor(private templateRef: TemplateRef<any>,private viewContainer: ViewContainerRef){ }
#Input()
setMyCustomIf(condition : boolean) {
if(condition) {
this.viewContainer.createEmbeddedView(this.templateRef);
} else {
this.viewContainer.clear();
}
}
}
app.module:
import { Directive, Input, TemplateRef, ViewContainerRef } from '#angular/core';
#Directive({
selector: '[myCustomIf]'
})
export class MyCustomeIfDirective{
constructor(private templateRef: TemplateRef<any>,private viewContainer: ViewContainerRef){ }
#Input()
setMyCustomIf(condition : boolean) {
if(condition) {
this.viewContainer.createEmbeddedView(this.templateRef);
} else {
this.viewContainer.clear();
}
}
}
app.component.html:
<h1 my-error>Hello {{name}}</h1>
<h2 *myCustomIf="condition">Hello {{name}}</h2>
<button (click)="condition = !condition">Click</button>
image:
If you open console it should show smth like:
NG0303: Can't bind to 'myCustomIf' since it isn't a known property of
'h2'
An Angular structural directive, that is written in a short syntax(with *) and that takes one input or more inputs, must have an #Input with the same name as directive's attribute selector(other inputs follow another rule described here What is the exact grammar for Angulars structural directives), e.g.:
#Directive({
selector: '[anyAttr]'
})
export class MyCustomeIfDirective{
#Input()
anyAttr: any;
or
#Directive({
selector: '[anotherAttr]'
})
export class MyCustomeIfDirective{
#Input()
set anotherAttr(val: any) {}
Why is it so?
That's because *ngIf is just a shortcut for expanded version:
<ng-template [ngIf]="...">...
or
*anyAttr => <ng-template [anyAttr]="...">...
Now, let's look at your code:
#Directive({
selector: '[myCustomIf]'
})
export class MyCustomeIfDirective{
#Input()
setMyCustomIf(condition : boolean) {
Several things to notice:
setMyCustomIf is just a method in your case
if you convert it to a setter set MyCustomIf then MyCustomIf doesnt match myCustomIf because js is case-sensitive.
The solution is:
#Input()
set myCustomIf(condition : boolean) {
Ng-run Example
in your directive (app.myCustomeIfDirective.ts), you need to match the name of your input to the name of the directive (because the condition is passed with that attribute):
#Input("myCustomIf")
set myCustomIf(condition : boolean) {
if(condition) {
this.viewContainer.createEmbeddedView(this.templateRef);
} else {
this.viewContainer.clear();
}
}
(note you can also change the name of the function to match the directive name)
stackblitz demo
How can I access a string of text given within the tags of a component
<my-custom-component>THIS TEXT</my-custom-component>
Within a template, I can use ng-content, or if it is an instance of some other class I can access it within the component definition like demonstrated in these examples. However I am interested in detecting if there is a string of text there or not, which I believe would make providedText undefined. However, I am always getting undefined.
#ContentChild(Element, { static: true }) providedText: Text | undefined;
I have tried Text as the first element passed to #ContentChild. Passing any will not work (I don't know why).
StackBlitz
I am interested mostly in finding if there is a string or undefined, but am also curious why ContentChild(Text... isn't working.
Edit:
I have added a potential solution, but it seems pretty imperfect, so I hope something better comes along.
Edit 2:
I now understand that #ContentChild is not a mechanism for selecting whatever native HTML I want without wiring it up to Angular’s dependency graph with a ref, directive, etc.
I am still curious if my proposed solution below is a bad idea for any reason.
My solution for now (since I wish to capture all transcluded content) is to wrap ng-content in a containing element, then get its innerText.
#Component({
selector: "app-parent",
template: `
<span #transcludedContainerRef>
<ng-content></ng-content>
</span>
`
})
export class ParentComponent implements AfterViewInit {
#ViewChild("transcludedContainerRef", { static: false })
transcludedContainerRef: ElementRef | undefined;
buttonText: string;
ngAfterViewInit() {
const isButtonTextPresent = this.transcludedContainerRef.nativeElement
.innerText;
if (isButtonTextPresent) {
console.log(isButtonTextPresent); // successfully logs content
}else {
console.log('No text set');
}
}
}
It does feel hacky, but it works. I am holding out for something better.
it's difficult if I don't know about your <my-custom-component>
In general if your custom component it's only
<ng-content></ng-content>
You can inject in constructor the elementRef
constructor(public el:ElementRef){}
From a parent
<hello >
Start editing to see some magic happen :)
</hello>
You can use
#ViewChild(HelloComponent,{static:false}) helloComponent:HelloComponent
click()
{
console.log(this.helloComponent.el.nativeElement.innerHTML)
}
If your component has any variable -or ViewContent-, you can access this variables in a similar way
So the other way to read the inner text from the component is that child component emit the value whatever it get's as input from other component. See below:
hello.component.ts
import { Component, Input, Output, EventEmitter, OnInit } from '#angular/core';
#Component({
selector: 'hello',
template: `<h1>Hello {{name}}!</h1>`,
styles: [`h1 { font-family: Lato; }`]
})
export class HelloComponent implements OnInit {
#Input() name: string;
#Output() innerText: EventEmitter<string> = new EventEmitter();
ngOnInit() {
this.innerText.emit(this.name);
}
}
app.component.ts
import { Component, ContentChild, AfterContentInit, OnInit } from "#angular/core";
#Component({
selector: "app-parent",
template: "content from <code>app-parent</code>"
})
export class ParentComponent implements AfterContentInit {
#ContentChild(Element, { static: true }) providedText: Text | undefined;
ngAfterContentInit() {
console.log("ngAfterContentInit Content text: ", this.providedText);
}
}
#Component({
selector: "my-app",
templateUrl: "./app.component.html",
styleUrls: ["./app.component.css"]
})
export class AppComponent {
name = "Angular";
_innerText: string;
ngAfterContentInit() {}
get childContent(): string {
return this._innerText;
}
set childContent(text) {
this._innerText = text;
}
innerTextFn(innertext: string) {
this.childContent = innertext;
console.log('Event: ', innertext);
}
}
app.component.html
<hello name="{{ name }}" (innerText)="innerTextFn($event)"></hello>
<app-parent>This is the content text</app-parent>
Here is stackblitz url to check: https://stackblitz.com/edit/angular-bacizp
I hope this may helpful for you and if yes then accept this as correct answer.
I need to know how to add to an html button the property (click) = function() of angular through Javascript.
Note: I cannot modify the HTML, I can only add the property through JavaScript.
I tested with addEventListener and it works by adding the common JavaScript click = "function" event, but not the (click) of Angular.
I attach the code:
import { Component, OnInit } from '#angular/core';
#Component({
selector: 'app-iframe',
templateUrl: './iframe.component.html',
styleUrls: ['./iframe.component.scss']
})
export class IframeComponent implements OnInit {
constructor() {}
ngOnInit() {
}
capture() {
let button = document.getElementById('cancelButton').addEventListener('(click)', this.cancel.bind(Event));
}
cancel() {
console.log('Cancelled');
}
}
And the HTML here:
<div class="row text-center pad-md">
<button id="acceptButton" mat-raised-button color="primary">OK!</button>
<button id="cancelButton" mat-raised-button>Cancel</button>
</div>
As stated by the author, the event need to be attached dynamically to the DOM element that is created after a request, so you can use Renderer2
to listen for the click event. Your code should look like this:
import { Component, OnInit, Renderer2 } from '#angular/core';
#Component({
selector: 'app-iframe',
templateUrl: './iframe.component.html',
styleUrls: ['./iframe.component.scss']
})
export class AppComponent implements OnInit {
name = 'Angular';
constructor(private renderer: Renderer2) {}
ngOnInit() {}
capture() {
const button = document.getElementById('cancelButton');
console.log(button);
this.renderer.listen(button, 'click', this.cancel);
}
cancel() {
console.log('Cancelled');
}
}
There's a functional example here.
Trying to do child to parent communication with #Output event emitter but is no working
here is the child component
import { Component, OnInit, Output, Input, EventEmitter } from '#angular/core';
#Component({
selector: 'app-emiter',
templateUrl: './emiter.component.html',
styleUrls: ['./emiter.component.css']
})
export class EmiterComponent implements OnInit {
#Output() emitor: EventEmitter<any>
constructor() { this.emitor = new EventEmitter()}
touchHere(){this.emitor.emit('Should Work');
console.log('<><><><>',this.emitor) // this comes empty
}
ngOnInit() {
}
}
this is the html template
<p>
<button (click)=" touchHere()" class="btn btn-success btn-block">touch</button>
</p>
The console.log inside the touchHere it shows nothing
even if I put this inside the parent component it show nothing as well
parent component
import { Component , OnInit} from '#angular/core';
// service I use for other stuff//
import { SenderService } from './sender.service';
// I dont know if I have to import this but did it just in case
import { EmiterComponent } from './emiter/emiter.component'
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'app';
user: any;
touchThis(message: string) {
console.log('Not working: ${message}');
}
constructor(private mySessionService: SenderService) { }
}
and here is the html template
<div>
<app-emiter>(touchHere)='touchThis($event)'</app-emiter>
</div>
Parent component template:
<app-emitor (emitor)='touchThis($event)'></app-emiter>
In parent template #Output should be 'called', not the child method.
Also, see: https://angular.io/guide/component-interaction#parent-listens-for-child-event
Here’s an example of how we write a component that has outputs:
#Component({
selector: 'single-component',
template: `<button (click)="liked()">Like it?</button>`
})
class SingleComponent {
#Output() putRingOnIt: EventEmitter<string>;
constructor() {
this.putRingOnIt = new EventEmitter();
}
liked(): void {
this.putRingOnIt.emit("oh oh oh");
}
}
Notice that we did all three steps: 1. specified outputs, 2. created an EventEmitter that we attached
to the output property putRingOnIt and 3. Emitted an event when liked is called.
If we wanted to use this output in a parent component we could do something like this:
#Component({
selector: 'club',
template: `
<div>
<single-component
(putRingOnIt)="ringWasPlaced($event)"
></single-component>
</div>`
})
class ClubComponent {
ringWasPlaced(message: string) { console.log(`Put your hands up: ${message}`);
} }
// logged -> "Put your hands up: oh oh oh"
Again, notice that:
putRingOnIt comes from the outputs of SingleComponent
ringWasPlaced is a function on the ClubComponent
$event contains the thing that wasemitted, in this case a string
<app-emiter (emitor)="touchThis($event)" ></app-emiter>
By using #Output() you should apply the event you need to emit in the directive of the emitter component.Adding the name of the variable to the the directive and but the emitted over function inside the quotation passing the $event.
touchHere() is the method from which you are binding some value to emit with your EventEmitter. And your EventEmitter is 'emitor'.
So your code will work if you simply do the below:
<app-emiter (emitor)='touchThis($event)'></app-emiter>
I have developed a custom directive which trims value of input controls.
Please find the code for the same:
import { Directive, HostListener, Provider } from '#angular/core';
import { NgModel } from '#angular/forms';
#Directive({
selector: '[ngModel][trim]',
providers: [NgModel],
host: {
'(ngModelChange)': 'onInputChange($event)',
'(blur)': 'onBlur($event)'
}
})
export class TrimValueAccessor {
onChange = (_) => { };
private el: any;
private newValue: any;
constructor(private model: NgModel) {
this.el = model;
}
onInputChange(event) {
this.newValue = event;
console.log(this.newValue);
}
onBlur(event) {
this.model.valueAccessor.writeValue(this.newValue.trim());
}
}
The problem is ngModel not updating value on onBlur event.
I tried to trim value on onModelChange event but it doesn't allow space between two words(e.g., ABC XYZ)
Any suggestion would be helpful.
Please add below lines of code in onblur event instead of existing code.It would work:
this.model.control.setValue(this.newValue.trim());
Thanks!