I want to add some text in showlist.component.html. My code is given below, I am not aware how to use document.body in Angular 2.
import { Component, OnInit } from '#angular/core';
import { DOCUMENT } from '#angular/platform-browser';
#Component({
selector: 'app-showlist',
templateUrl: './showlist.component.html',
styleUrls: ['./showlist.component.css']
})
export class ShowlistComponent implements OnInit {
public myname = "saurabh";
constructor() { }
ngOnInit() {
//this.myname.appendTo(document.body);
document.body(this.myname);
//document.write(this.myname);
}
}
you do the following to access the document.body
import { Component, OnInit, Inject } from '#angular/core';
import { DOCUMENT } from '#angular/common';
#Component({
selector: 'app-showlist',
templateUrl: './showlist.component.html',
styleUrls: ['./showlist.component.css']
})
export class ShowlistComponent implements OnInit {
public myname = "saurabh";
constructor(#Inject(DOCUMENT) private document: Document) {}
ngOnInit() {
this.document.body.innerHTML = this.myname;
}
}
Related
I am fairly new to the Angular world and working on angular 7, I am doing some examples where components share data within, The Parent to child part working fine but when i am trying to send any values from child to parent it's not working.
It shows me this error
app-component.html
<div>{{show}}</div>
<app-communicating-components [Parent]="message" (childEvent)="getMessage($event)"></app-communicating-components>
app-component.ts
import { Component } from '#angular/core';
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'AngularLesson2';
public message = 'Hello my child, Parents here';
public show: string;
getMessage($event) {
this.show = $event;
}
}
communicating-components.component.html
<p>
{{Parent}}
</p>
<button (click)="fireEvent()">Fire from child</button>
communicating-components.component.ts
import { Component, OnInit, Input, Output } from '#angular/core';
import { EventEmitter } from 'events';
#Component({
selector: 'app-communicating-components',
templateUrl: './communicating-components.component.html',
styleUrls: ['./communicating-components.component.css']
})
export class CommunicatingComponentsComponent implements OnInit {
#Input() Parent;
#Output() public childEvent = new EventEmitter();
constructor() {
}
ngOnInit() {
}
fireEvent() {
this.childEvent.emit('Hi, I am child');
console.log("event fire" + this.childEvent);
}
}
What am I doing wrong here?
I believe the problem is in your import import { EventEmitter } from 'events'; is not the one you should import here. Try changing the import to import { EventEmitter } from '#angular/core';
UPDATE
Here's a stackblitz example showing that it works
With Angular newer versions, like 8 you have to:
Import correctly Emitter as k.s. said:
import { EventEmitter } from '#angular/core'
Initialize the emitter for Output:
#Output()
emisor = new EventEmitter<type>();
Im having some trouble figuring this out, basically I have a headerTitleService which I want to be able to dynamically set the title in my header component but for some reason when I set the title nothing shows up? Im not getting any errors so I can seem to figure out what the problem is..
headerTitle.service.ts
import { Injectable } from '#angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
#Injectable()
export class HeaderTitleService {
title = new BehaviorSubject('');
constructor() { }
setTitle(title: string) {
this.title.next(title);
}
}
header.component.ts
import { Component, OnInit } from '#angular/core';
import { HeaderTitleService } from '../../../services/headerTitle.service'
#Component({
selector: 'app-header',
templateUrl: './header.component.html',
styleUrls: ['./header.component.scss'],
providers: [HeaderTitleService]
})
export class HeaderComponent implements OnInit {
title: string;
constructor(
private headerTitleService: HeaderTitleService
) { }
ngOnInit() {
this.headerTitleService.title.subscribe(updatedTitle => {
this.title = updatedTitle;
});
}
}
header.component.html
<h1>{{title}}</h1>
home.component.ts
import { Component, OnInit } from '#angular/core';
import { HeaderTitleService } from '../../services/headerTitle.service';
#Component({
selector: 'app-home',
templateUrl: './home.component.html',
styleUrls: ['./home.component.scss'],
providers: [HeaderTitleService]
})
export class HomeComponent implements OnInit {
constructor(
private headerTitleService: HeaderTitleService
) { }
ngOnInit() {
this.headerTitleService.setTitle('hello');
}
}
The line providers: [HeaderTitleService] in each component means that they will be given one HeaderTitleService each, rather than one between them.
To fix this remove providers: [HeaderTitleService] from your components, and place it in your module definition instead:
#NgModule({
providers: [HeaderTitleService]
})
Move HeaderTitleService in providers of your module. With your implementation you receive new instance of the HeaderTitleService in each component.
Hope this helps.
I'm using a service to pass data between child and parent with the purpose being to update the parent ui with child specific info depending on what child is loaded.
Service:
import { Subject } from "rxjs/Subject";
export class ChildDataService {
private childDetails = new Subject<{}>();
childLoaded$ = this.childDetails.asObservable();
changedComponentName(option: {}){
this.childDetails.next(option);
}
}
Parent Component:
import { Component, OnInit, ViewEncapsulation } from '#angular/core';
import { ChildDataService } from "../core/helpers/child-data.service";
import { Subscription } from "rxjs/Subscription";
#Component({
selector: 'app-parent',
templateUrl: './parent.component.html',
styleUrls: ['./parent.component.scss'],
encapsulation: ViewEncapsulation.None
})
export class ParentComponent implements OnInit {
childDetails: {title?: string};
private subscription:Subscription;
constructor( private childDataService: ChildDataService) {
this.childDataService.childLoaded$.subscribe(
newChildDetails => {
console.log(newChildDetails);
this.childDetails = newChildDetails
});
}
}
Example Child Component:
import { Component, OnInit, ViewEncapsulation } from '#angular/core';
import { ChildDataService } from "../../core/helpers/child-data.service";
#Component({
selector: 'app-child-dashboard',
templateUrl: './child-dashboard.component.html',
styleUrls: ['./child-dashboard.component.scss'],
encapsulation: ViewEncapsulation.None
})
export class ChildDashboardComponent implements OnInit {
constructor(private childDataService: ChildDataService) { }
public ngOnInit() {
this.childDataService.changedComponentName({
title: 'Dashboard'
});
}
}
Parent HTML:
<div class="subheader">
<h1>{{ childDetails?.title }}</h1>
<button *ngIf="childDetails?.title == 'Dashboard'">dashboard</button>
<button *ngIf="childDetails?.title == 'SecondChild'">Second Child</button>
</div>
With this setup I am getting the error "ExpressionChangedAfterItHasBeenCheckedError" when i click on a routerLink, now if i click on the same link a second time, the error persists but the correct button becomes visible. Spent all weekend getting nowhere with this, so any help would be greatly appreciated.
public ngOnInit() {
setTimeout(() => {
this.childDataService.changedComponentName({
title: 'Dashboard'
}), {});
}
it should work.
async ngOnInit() {
await this.childDataService.changedComponentName({
title: 'Dashboard'
});
}
This is my .ts file
import { Component, OnInit } from '#angular/core';
import { AngularFireDatabase, FirebaseListObservable, FirebaseObjectObservable } from 'angularfire2/database';
#Component({
selector: 'app-candidate-reg-success',
templateUrl: './candidate-reg-success.component.html',
styleUrls: ['./candidate-reg-success.component.css']
})
export class CandidateRegSuccessComponent implements OnInit {
constructor() {
debugger;
const rootRef=firebase.database.ref();
const mail=rootRef.child('candidates_list').orderByChild('email').equalTo('pranavkeke#gmail.com');
console.log(mail);
}
ngOnInit() {
}
}
I am trying to query the user from candidates_list table which has the email address pranavkeke#gmail.com.
But I am unable to console it. It shows a error like
Property 'ref' does not exist on type 'typeof database'.
Any solution to query angular firebase database?
you need to inject the AngularFirebaseData in constructor and change the code and try again
import { Component, OnInit } from '#angular/core';
import { AngularFireDatabase, FirebaseListObservable,
FirebaseObjectObservable } from 'angularfire2/database';
#Component({
selector: 'app-candidate-reg-success',
templateUrl: './candidate-reg-success.component.html',
styleUrls: ['./candidate-reg-success.component.css']
})
export class CandidateRegSuccessComponent implements OnInit {
constructor(public db: AngularFireDatabase) {
debugger;
db.list('/candidates_list', ref => ref.orderByChild('email').equalTo('pranavkeke#gmail.com'));
}
ngOnInit() {
}}
I am trying to implement angular2-virtual-scroll in an angular4 project. Firstly, can anyone confirm if I would have a problem implementing it in NG4. I don't think I should and I haven't seen any notices to the contrary. Secondly I am using an observable instead of a promise shown in the NPM angular2-virtual-scroll docs. However, when I applied the virtual-scroll tag there is no change in my output...no scroll bar ..the data from the observable is displayed but no scrolling. The following are the relevant code segments:
Home.component.html
<h1 style="color: #76323f">
{{title}}
</h1>
<h4>
{{description}}
</h4>
<h2>Coming Soon....</h2>
<app-events-list [upcomingEvents]="upcomingEvents"></app-events-list>
home.component.ts
import {Component, OnInit,OnDestroy } from '#angular/core';
import {UpcomingEvent} from './../../interface/upcomingevent';
import {EventService} from './../../services/event.service';
import {Subscription} from 'rxjs/Subscription';
#Component({
selector: 'app-home',
templateUrl: './home.component.html',
styleUrls: ['./home.component.css']
})
export class HomeComponent implements OnInit, OnDestroy {
upcomingEvents: Array<UpcomingEvent>;
title = 'Welcome....';
description='Events promotions....';
eventServiceSub: Subscription;
constructor(private eventService: EventService){
this.upcomingEvents = [];
}
ngOnInit() {
this.eventServiceSub=this.eventService.getEvents().subscribe(upcomingEvents=>{this.upcomingEvents=upcomingEvents.slice(0,25);
});
}
ngOnDestroy(){
if (this.eventServiceSub){
this.eventServiceSub.unsubscribe();
}
}
}
event-list-component.html
<virtual-scroll [items]="items" (update)="upcomingEvents = $event"
(change)="onlistChange($event)">
<app-upcomingevent *ngFor="let upcomingEvent of upcomingEvents"[upcomingEvent]="upcomingEvent" [eventItemCss]="'event-item'"></app-upcomingevent>
<div *ngIf="loading" class="loader">Loading.....</div>
</virtual-scroll>
event-list-component.ts
import { Component, Input, OnDestroy, OnInit } from '#angular/core';
import { UpcomingEvent } from './../../interface/upcomingevent';
import { trigger,state,style,transition,animate,keyframes } from '#angular/animations';
import { ChangeEvent } from 'angular2-virtual-scroll';
import {EventService} from './../../services/event.service';
import {Subscription} from 'rxjs/Subscription';
#Component({
selector: 'app-events-list',
templateUrl: './events-list.component.html',
styleUrls: ['./events-list.component.css'],
animations: []
})
export class EventsListComponent implements OnInit, OnDestroy {
#Input()
upcomingEvents: Array<UpcomingEvent>;
items=this.upcomingEvents;
protected buffer: Array<UpcomingEvent> =[];
protected loading: boolean;
eventServiceSub: Subscription;
constructor(private eventService: EventService) {
this.upcomingEvents=[];
}
ngOnInit() {
}
ngOnDestroy(){
if (this.eventServiceSub){
this.eventServiceSub.unsubscribe();
}
}
protected onlistChange(event: ChangeEvent){
if (event.end !==this.buffer.length) return;
this.loading=true;
this.eventServiceSub=this.eventService.getEvents().subscribe(upcomingEvents=>{
this.buffer=upcomingEvents.slice(this.buffer.length,25);
this.loading=false;
}, ()=> this.loading=false);
}
}
eventService.ts
import { Injectable } from '#angular/core';
import {UpcomingEvent} from './../interface/upcomingevent'
import {Http} from '#angular/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';
#Injectable()
export class EventService {
constructor(private http: Http) { }
getEvents(): Observable<UpcomingEvent[]>
{
return this.http
.get(`https://jsonplaceholder.typicode.com/posts`)
.map(response => response.json() as UpcomingEvent[]);
}
}
upcomingEvents.html
<md-card [ngClass]="'event-item'">
<h4 [ngClass]="'event-title'" [ngStyle]="{'color':'purple'}"> {{upcomingEvent.title}}</h4>
<md-card-actions>
<button md-button>LIKE</button>
<button md-button>SHARE</button>
</md-card-actions>
</md-card>
upcomingEvents.component.ts
import { Component, Input,OnInit } from '#angular/core';
import { UpcomingEvent } from './../../interface/upcomingevent';
#Component({
selector: 'app-upcomingevent',
templateUrl: './upcomingevent.component.html',
styleUrls: ['./upcomingevent.component.css']
})
export class UpcomingeventComponent implements OnInit {
#Input()
upcomingEvent: UpcomingEvent;
#Input()
eventItemCss: string;
constructor() { }
ngOnInit() {
if (!this.upcomingEvent) {
this.upcomingEvent=<UpcomingEvent> {};
}
}
}
The way it suppose to work is that the HomeComponent request data from the eventService via an observable..the data is then passed to the eventList component where it is iterated on and pass to the upcomingEvents component to present via HTML. 25 events are requested at first and if the user scroll to the end another 25 is requested from the eventService...this time by the upcomingEvents component. I am not sure this is the most efficient way to do it but in either case it doesn't work. The virtual-scroll seems to have no effect on the output....I would really appreciate someone showing me what I am doing wrong....Thanks
I think I see a problem in your code. When using virtual-scroll you need to keep two arrays - one for all loaded data, and one for currently rendered items. Looks like you kinda mixed them up.
Let's call all-items-array as items and render-array - upcomingEvents
First chunk of items will be passed from the parent component, hence:
Home.component.html
...
<app-events-list [items]="upcomingEvents"></app-events-list>
event-list-component.html looks good
event-list-component.ts
import { Component, Input, OnDestroy, OnInit } from '#angular/core';
import { UpcomingEvent } from './../../interface/upcomingevent';
import { trigger,state,style,transition,animate,keyframes } from '#angular/animations';
import { ChangeEvent } from 'angular2-virtual-scroll';
import {EventService} from './../../services/event.service';
import {Subscription} from 'rxjs/Subscription';
#Component({
selector: 'app-events-list',
templateUrl: './events-list.component.html',
styleUrls: ['./events-list.component.css'],
animations: []
})
export class EventsListComponent implements OnInit, OnDestroy {
#Input()
items: Array<UpcomingEvent> = [];
upcomingEvents: Array<UpcomingEvent>;
protected loading: boolean;
eventServiceSub: Subscription;
constructor(private eventService: EventService) {
this.upcomingEvents=[];
}
ngOnInit() {
}
ngOnDestroy(){
if (this.eventServiceSub){
this.eventServiceSub.unsubscribe();
}
}
protected onlistChange(event: ChangeEvent){
if (event.end !==this.items.length) return;
this.loading=true;
this.eventServiceSub=this.eventService.getEvents().subscribe(upcomingEvents=>{
this.items=upcomingEvents.slice(0, this.items.length + 25);
this.loading=false;
}, ()=> this.loading=false);
}
}
warning! code not tested, I simply edited your code.