How can I reload the same component again in Angular 2?
Here is my code below:
import { Component, OnInit, ElementRef, Renderer } from '#angular/core';
import { Router, ActivatedRoute, Params } from '#angular/router';
import { productModel } from '../_models/index';
import { categoryListService } from '../_services/index';
#Component({
selector: 'app-product',
templateUrl: 'product.component.html',
styleUrls: ['product.component.css']
})
export class productComponent implements OnInit {
uidproduct: productModel;
param: number;
constructor(
private elementRef: ElementRef,
private route: ActivatedRoute,
private router: Router,
private categoryListService: categoryListService) { }
ngOnInit() {
this.route.params.subscribe(product => {
console.log('logging sub product obj', product);
});
this.uidproduct = JSON.parse(sessionStorage.getItem('product'));
var s = document.createElement("script");
s.type = "text/javascript";
s.src = "http://this/external/script/needs/to/be/loaded/each/time.js";
this.elementRef.nativeElement.appendChild(s);
}
nextproduct(){
let i = this.uidproduct.order;
this.categoryListService.findNextproduct(this.uidproduct);
this.param = ++i;
this.router.navigate([`/product/${this.param}`]);
}
}
nextproduct() is bound to a click event in the template.
The uidproduct is a JSON object that has a number of properties and i'm updating the DOM with {{uidproduct.classname}}
I'm using this in the template like this:
<div id="selected-product" class="{{uidproduct.classname}}">
When I click the <button (click)="nextproduct()"> it will change the class property in the DOM but I need to reload the component for the external script to have effect.
You can use *ngIf to re-render the content of a template:
#Component({
selector: '...',
template: `
<ng-container *ngIf="!rerender">
template content here
</ng-container>`
})
export class MyComponent {
rerender = false;
constructor(private cdRef:ChangeDetectorRef){}
doRerender() {
this.rerender = true;
this.cdRef.detectChanges();
this.rerender = false;
}
}
I don't understand why you need to reload the component. If you're binding to the various fields of uidproduct, then reloading that should refresh the values shown in the component. So reloading the component does nothing but add overhead.
If there is a terrific reason not mentioned here why you think you still need to do this, then here is what you do:
Navigate to another (possibly blank) component.
Navigate directly back.
The problem is that you need to wait for the first navigation to finish before doing the second one.
In your component, import NavigationEnd:
import { Router, NavigationEnd } from '#angular/router';
And then subscribe to it in your constructor:
constructor(private thingService: ThisThingService, private router: Router) {
router.events.subscribe(event => {
if (event instanceof NavigationEnd) {
if (event.url === '/blank') {
this.router.navigate(['product']);
}
}
});
Notice that I wait for NavigationEnd to happen and then check to see I was routing to my blank component. If it is the blank component's path, I navigate back to the product. If you really need to pass that ID, just store it on your object and add it here.
Instead of routing to your product page in nextproduct(), navigate to blank.
this.router.navigate(['blank']);
And that should reload your component perfectly fine.
The problem I intentionally left in for simplicity, is that the subscribe call in the constructor will execute for every reload. So as an exercise to the reader, take it out of the constructor and create a nice service for it, or move it to the constructor of your app component, or maybe to your routing module or wherever makes sense to you.
Related
I have some pages and when I change router link to some wrong url and it redirect me to 404 page. In this 404 Error page I have button that will redirect me to previous page. Now I have some problems that this redirect button when I click it redirects to that wrong url and again to 404.
I try to show by photo:
1)My route. write wrong url -> redirect to 404 page.
Now the problem is when I click button to redirect at the previous route "Home" it redirect me to this wrong route.
goBack() {
this._location.back();
}
You can use JS history API to achieve this.
This is a sample to match your use case
goBack() {
window.history.go(-2);
}
And this also keeps navigiation within the SPA scope (Page wouldn't refresh).
Side effect for this is that you need to make sure that the user follows a particular flow; in which he needs to be within a working page, then goes somewhere not found then get redirected to the 404 Page..
I would recommend a button that navigates to Home or Dashboard features instead.
You can achieve this by number of ways , however I think the most elegant way is to use power of Injectable services in Angular.
Here is my solution of this problem:
Create an Injectable service which will set a variable as soon as the current navigation end. The value of this variable can be used in any of the other components where ever we would need. Obviously one has to inject the service in the required component.
In my example, I have created RouterService:
import { Injectable } from '#angular/core';
import { Router, NavigationEnd } from '#angular/router';
#Injectable({ providedIn: 'root' })
export class RouterService {
private previousUrl: string = undefined;
private currentUrl: string = undefined;
constructor(public router : Router) {
this.currentUrl = this.router.url;
router.events.subscribe(event => {
if (event instanceof NavigationEnd) {
this.previousUrl = this.currentUrl;
this.currentUrl = event.url;
};
});
}
public getPreviousUrl(){
return this.previousUrl;
}
}
To illustrate the navigation , I have created two components viz. home and not-found Components.
Below are the code snippets for both of these components :
a) home.component.ts :
import { Component, VERSION } from '#angular/core';
import { NavigationEnd, Router } from '#angular/router';
import { filter } from 'rxjs/operators';
import { RouterService } from '../../service/router.service';
#Component({
selector: 'not-home-app',
templateUrl: './home.component.html',
styleUrls: [ './home.component.scss' ]
})
export class HomeComponent {
name = 'Angular ' + VERSION.major;
constructor(private router: Router,private routerService: RouterService) {}
takeMeToNotFoundPage(){
this.router.navigate(['/notFound']);
}
}
b) not-found.component.ts:
import { Component, VERSION } from '#angular/core';
import { NavigationEnd, Router } from '#angular/router';
import { filter } from 'rxjs/operators';
import { RouterService } from '../../service/router.service';
#Component({
selector: 'not-found-app',
templateUrl: './not-found.component.html',
styleUrls: [ './not-found.component.scss' ]
})
export class NotFoundComponent {
previousUrl: string;
constructor(private router: Router, private routerService: RouterService) {
router.events
.pipe(filter(event => event instanceof NavigationEnd))
.subscribe((event: NavigationEnd) => {
console.log('prev:', event.url);
this.previousUrl = event.url;
});
}
loadPreviousRoute(){
let previous = this.routerService.getPreviousUrl();
if(previous)
this.routerService.router.navigateByUrl(previous);
}
}
When the application will first load, I will route it to 'home' page. There I provided a button to navigate to not-found page.
As you see in the above code of home component , I am setting the previous url in the router service which I can use in next component ( in this example it is 'not-found' component'
c) below are the html code snippets for both home and not-found components :
Home.component.html :
<hello name="{{ name }}"></hello>
<p>
Start editing to see some magic happen :)
</p>
<button type="button" (click)="takeMeToNotFoundPage()">Not FOUND!</button>
not-found.component.html:
<p>
<span style="background-color: red">NOT FOUND!!</span>
</p>
<button type="button" (click)="loadPreviousRoute()">Go Back to Previous Route</button>
Hope this will help you to solve your problem. If it will , please provide your feedback and upvote it accordingly as it will help others in future too.
I want to show taxDetailsId in my child component Html page.
But when click submit button.
After click submit button then shows taxDetailsId in my child component Html page.
Parent Component
export class OnlinePaymentComponent implements OnInit {
HttpClient: any;
paymentForm: FormGroup = this.formBuilder.group({
taxDetailsId: ['', [Validators.required]]
});
constructor(
private formBuilder: FormBuilder,
private router: Router,
) {}
ngOnInit() {}
submitForm(): void {
if (!this.paymentForm.valid) {
this.router.navigate(['/home/online-payment/error']);
return;
}
}
}
Parent.Component.html
<form [formGroup]="paymentForm" (ngSubmit)="submitForm()">
<label>Tax Details Id</label>
<input type="text" formControlName="taxDetailsId" placeholder="Tax Details Id" />
<button>Pay Bill</button>
<form>
Child Component
export class OnlinePaymentErrorComponent implements OnInit {
constructor() { }
ngOnInit(): void {
}
}
Child.Component.html
<div>
<button [routerLink]="['/home/online-payment']" >Back Home</button>
</div>
you can try this pattern this.router.navigate(['/heroes', { id: heroId }]);
https://angular.io/guide/router
you can use angular #Input() decorator for it.
Child Component
import { Component, Input } from '#angular/core';
export class ChileComponent {
#Input() public taxDetailsId: number;
}
Child Component HTML
enter code here
<div>
{{ taxDetailsId }}
<button [routerLink]="['/home/online-payment']" >Back Home</button>
</div>
Parent Component HTML
<app-child-component [taxDetailsId]="taxDetailsId"> </app-child-component>
https://angular.io/guide/inputs-outputs
You can pass components around using Angular's InjectionToken.
First you start off by creating the token:
export const ONLINE_PAYMENT_REF = new InjectionToken<OnlinePaymentComponent>('OnlinePaymentComponent');
Next you add the token to one of the root components as a provider, in this case it is the OnlinePaymentComponent. This way everything that is a child of this component, and everything that is a child of those components, and so on; will have a reference to the main parent that we create here:
#Component({
selector: 'online-payment',
template: `
<online-payment-error></online-payment-error>
`,
providers: [
{
provide: ONLINE_PAYMENT_REF,
// Forwards the instance of OnlinePaymentComponent when injected into
// the child components constructor.
useExisting: forwardRef(() => OnlinePaymentComponent)
}
]
})
export class OnlinePaymentComponent {
message = 'I am the Online Payment Component';
}
Now that we have the main component setup, we can access it through the constructor of anything that is a child of OnlinePaymentComponent (no matter how deep it is).
#Component({
selector: 'online-payment-error',
template: `
<h2>Child</h2>
<strong>Parent Message:</strong> {{parentMessage}}
`
})
export class OnlinePaymentErrorComponent implements OnInit {
parentMessage = '';
constructor(
#Inject(ONLINE_PAYMENT_REF) private parent: OnlinePaymentComponent
) {}
ngOnInit() {
this.parentMessage = this.parent.message;
}
}
When all is said and done, you will see the following:
The pros of this method are that you don't have to bind values to the elements in the template, and if those components have components that need to reference the parent you wouldn't have to bind to those either. Since components look up the hierarchy till they find the first instance of the provider that we are looking for they will find the one in OnlinePaymentComponent.
This becomes very helpful when components get deeper and deeper into the parent component (say 5 levels deep), that means every time you would have to pass a reference to the template element 5 times, and if it changes or gets deeper you would have to update all the templates.
With this method we no longer need to update templates to pass data from one component to another component, we just request it in our constructor as seen in OnlinePaymentErrorComponent.
There are two simple ways:
Using query params (without routerLink).
Using Observables.
Using query params, you can use the router.navigate and pass the params you need (Id) along with the route.
eg: this.route.navigate(['yourroute/route', { tId: variableWithId }])
Using Observable, when you click on the button, use the same router navigate without params and pass the required data to an observable. On successful routing to the next page, get the resolved data from the observable.
I have a child TestComponent component as follows:
import { Component, OnInit, Input } from '#angular/core';
import { ApiService } from '../../../api.service';
#Component({
selector: 'app-test',
templateUrl: './test.component.html'
})
export class TestComponent implements OnInit {
constructor(private apiService: ApiService) { }
testDisplayMessage = 'No data to show';
ngOnInit() {
}
getMessage(param: string) {
this.callingTest = true;
this.apiService.getTest( param ).subscribe( data => {
this.setTestDisplayMessage( data );
this.callingTest = false;
}, err => {
console.log( JSON.stringify( err ) );
this.setTestDisplayMessage( 'Failed to get data' );
this.callingTest = false;
} );
}
setTestDisplayMessage( message: string ) {
this.testDisplayMessage = message;
}
}
contents of test.component.html
<p style="padding: 10px;">{{ testDisplayMessage }}</p>
Use in parent componet :
Trigger JS Code in parent component on button click,
import { TestComponent } from './test/test.component';
....
.....
#Component({
providers: [ TestComponent ],
templateUrl: 'parent.component.html'
})
export class ParentComponent implements OnInit {
...
constructor(private testComponent: TestComponent) { }
...
// Button on parent template triggers this method
getMessage() {
this.testComponent.getMessage('Hello');
}
...
}
Html tag added in parent component,
<app-test></app-test>
When I debugged above code trigger point, call to setTestDisplayMessage() happens the field testDisplayMessage in TestComponent gets changed but UI shows the old message 'No data to show', why is the message on change does not reflect on UI template? Or this is not the way it is supposed to get used? Shall I use #Input
Update:
Based on the pointers given in the following answers as well as comment sections, I changed my component as #ViewChild so in above parent component instead of passing the child component as an argument to constructor I declared it as child component using #ViewChild, so code changes as follows,
Earlier wrong code
constructor(private testComponent: TestComponent) { }
Solution
#ViewChild(TestComponent)
testComponent: TestComponent;
I found this article useful.
Use #ViewChild()
In html file:
<app-test #childComp></app-test>
In parent component.ts file
import { Component, OnInit, ViewChild } from '#angular/core';
....
.....
#Component( {
templateUrl: 'parent.component.html'
} )
export class ParentComponent implements OnInit {
#viewChild('childComp') childComp: any;
constructor() { }
...
// Button on parent template triggers this method
getMessage() {
this.childComp.getMessage('Hello');
}
...
}
Update:
Based on the pointers given in the following answers as well as comment sections, I changed my component as #ViewChild so in above parent component instead of passing the child component as an argument to constructor I declared it as child component using #ViewChild, so code changes as follows,
Earlier wrong code
constructor(private testComponent: TestComponent) { }
Solution
#ViewChild(TestComponent)
testComponent: TestComponent;
I found this article useful.
definitely use #Input() but on set method
#Input()
set someProperty(value) {
// do some code
}
now every time you pass new value here, code will run
basically, your approach is wrong, please use Input() or Services to share data between components.
however, if you want to make ur code work, the below may work
import change detector
constructor(private cdRef: ChangeDetectorRef) {
}
note: import reference ->
import { ChangeDetectorRef } from '#angular/core';
execute detect change after the value is updated
setTestDisplayMessage( message: string ) {
this.testDisplayMessage = message;
this.cdRef.detectChanges();
}
I hope this helps
i'm struggling about this problem and can't figure out.
I simply need to show a popup div situated in the page clicking from a menu entry in my navbar.component.
I added a property "show" in my popup which prints the "show" class on my div using the ngClass (with if) directive. I can get this working if the action button is inside my popup component but i cannot print the show class clicking on another component. The property in the Object get updated but the class is not printed. I'm using angular 4 with ng-bootstrap. I tried both with services and with parent/child emit event.
This is is my situation:
app.component.html
<app-nav-bar></app-nav-bar>
<app-login></app-login>
<router-outlet></router-outlet>
<app-footer></app-footer>
navbar.component.html
...
<button class="dropdown-item" (click)="showPopup()">LOGIN</button>
...
navbar.component.ts
import {Component, EventEmitter, Input, OnInit, Output} from '#angular/core';
#Component({
moduleId: module.id,
selector: 'app-nav-bar',
templateUrl: 'navbar.component.html',
styleUrls: ['./navbar.component.css'],
})
export class NavbarComponent implements OnInit {
#Output() show = new EventEmitter<boolean>();
ngOnInit() {
}
showPopup() {
this.show.emit(true);
}
}
login.component.html
<div id="wrapper-login-popup" class="fade-from-top" [(class.show)]="show">
<div id="container-login-popup">
<div class="row">
<div class="col-sm-12 text-center">
<img id="popup-bomb" src="assets/images/bomb.png" alt="bomb"/>
<img id="popup-close" class="close-icon" src="assets/images/close.png" alt="close"
(click)="closePopup()"/>
</div>
</div>
</div>
</div>
login.component.ts
import {Component, Input, OnInit} from '#angular/core';
import {AuthService} from '../services/auth.service';
import {IUser} from './user';
#Component({
selector: 'app-login',
templateUrl: 'login.component.html',
styleUrls: ['login.css']
})
export class LoginComponent implements OnInit {
private username: string;
private password: string;
#Input() show: boolean = false;
constructor(private AuthService: AuthService) {
}
ngOnInit() {
}
login() {
...
}
showPopup() {
console.log(this); //Show is false
this.show = true;
console.log(this); //Show is true but does not trigger the show class
}
closePopup() {
this.show = false;
}
}
The issue here is that your nav-bar and login components are siblings and can't directly communicate with each other. You have show as an output of navbar and as an input of login, but you haven't connected the dots.
You need to update your app.component to connect them.
export class AppComponent implements OnInit {
show = false;
onShow() { this.show = true; }
}
and in the template:
<app-nav-bar (show)="onShow()"></app-nav-bar>
<app-login [(show)]="show"></app-login>
There's a lot of two way binding going on here which works for something simple liek this, but generally it's a bad idea as it leads to unmaintainable code. You should choose one owner of the show variable and force all changes to it through him. In this case the app component is the most logical owner, so I'd change the login component to emit an event that changes the show variable in app component adn remove all 2 way bindings, but in a bigger app, you may even want a separate service that manages hiding/showing pop ups. This eliminates the need for the sending a message up and down your component tree, you can inject the service where it's needed.
As another commenter mentioned, you also should be using ngClass for class manipulation like
[ngClass]="{'show':show}"
a service based solution would look like
import {Subject} from 'rxjs/Subject';
#Injectable()
export class PopUpService {
private showPopUpSource = new Subject();
showPopUp$ = this.showPopUpSource.asObservable();
showPopUp() { this.popUpSource.next(true); }
closePopUp() { this.popUpSource.next(false); }
}
Then you provide in app module or at app component level:
providers:[PopUpService]
make sure you don't re provide this later, as you only want one copy to exist so everyone shares it.
then inject into both components, and have them call the services close or show pop up methods.
then in the login component you bind to the popUp$ observable like
constructor(private popUpSvc:PopUpService){}
show$;
ngOnInit() { this.show$ = this.popUpSvc.showPopUp$; }
showPopUp() { this.popUpSvc.showPopUp(); }
closePopUp() { this.popUpSvc.closePopUp(); }
and in the template subscribe w async pipe like
<div id="wrapper-login-popup" class="fade-from-top" [ngClass]="{'show': (show$ | async) }">
The reason for using the async pipe is garbage collection managemetn is simpler. If you don't use async, you need to garbage collect manually in ngOnDestroy by calling unsubscribe(), otherwise your subscriptions will keep stacking up. There is also a more nuanced benefit in that the async pipe triggers change detection, but this only becomes important if you start using onPush change detection for performance optimization.
I've got a small Plunk I'm using for playing around with the new Router 3.0 alpha currently available in Angular 2. It works well in general, but the issue is that once I click on a link that routes to the 'detail' component with a particular ID, it never changes when I click on a different link with a different ID. The component is never being reinstantiated, so it only ever shows what it was passed the very first time it is loaded.
Here's the component in question:
import { Component, OnInit } from '#angular/core';
import { ActivatedRoute } from '#angular/router';
import { ContactsService } from './contacts.service';
#Component({
selector: 'contacts-detail',
template: `
<h2>{{contact.name}}</h2>
`
})
export class ContactsDetailComponent implements OnInit {
constructor(private contactsService: ContactsService, private route: ActivatedRoute) {
}
ngOnInit() {
this.contact = this.contactsService.getContact(this.route.snapshot.params.id);
console.log('Fetching user', this.route.snapshot.params.id);
}
}
Here is the Plunk demonstrating the problem. Click on one author name and then another to see it not change.
In your ContactsDetailComponent, change the OnInit to this:
ngOnInit() {
this.sub = this.route.params.subscribe(params => {
let id = +params['id'];
this.contact = this.contactsService.getContact(id);
});
}
Worked for me in your Plunk.
There appear to be multiple lifeCycle hooks that could possibly be used for this. I managed to get the desired behavior using the DoCheck interface and implementing the associated ngDoCheck() method in the component class, as seen below.
import { Component, DoCheck } from '#angular/core';
import { ActivatedRoute } from '#angular/router';
import { ContactsService } from './contacts.service';
#Component({
selector: 'contacts-detail',
template: `
<h2>{{contact.name}}</h2>
`
})
export class ContactsDetailComponent implements AfterViewChecked, DoCheck {
constructor(private contactsService: ContactsService, private route: ActivatedRoute) {
}
ngDoCheck() {
this.contact = this.contactsService.getContact(this.route.snapshot.params.id);
}
}
Here's a plunk with the updated code.
I'm not convinced this is the best/correct lifecycle hook to use, though. Perhaps there is some sort of hook available from the Router that would serve this better.
Another way to do this:
ngOnInit() {
this.route.params.forEach((params: Params) => {
let id = +params['id'];
this.contact = this.contactsService.getContact(id);
});
}
Here retrieve the route params from an Observable. The advantage of using an Observable over Snapshot is to reuse the component without instantiating it again. Looks like this is the recommended way of doing this as per Angular 2.0 final documentation.