Using #ViewChild { read: ElementRef } of component causes unit test to fail - javascript

In my component I have a child component that looks like this:
<child-component #childComponent></childComponent>
In my parent component I then access this child component using #ViewChild and the read parameter to get the ElementRef, and not the component reference. I need the ElementRef to ensure I can get some properties from nativeElement that I need. So it's like this:
export class ParentComponent {
#ViewChild('childComponent', { read: ElementRef }) public childComponent: ElementRef;
public position: string;
// some way down the code
private someMethod() {
if (this.childComponent.nativeElement.offsetLeft > 500) {
this.position = 'left';
} else {
this.position = 'right';
}
}
}
So this works for the application, however I am writing the tests and mocking the child component, like this:
#Component({
selector: 'child-component',
template: ''
})
class ChildComponentMockComponent {
private nativeElement = {
get offsetLeft() {
return 600
}
};
}
beforeEach(async(() => TestBed.configureTestingModule({
imports: [ ... ],
declarations: [ ParentComponent, ChildComponentMockComponent ],
providers: [ ... ],
schemas: [ NO_ERRORS_SCHEMA ]
}).compileComponents()));
it('should have the correct position, based on position of child-component', () => {
spyOn(component, 'someMethod');
expect(component.someMethod).toHaveBeenCalled();
expect(component.position).toBe('left');
});
So the test will compile the component, and use the mocked child component values as the proper value and compute the value of this.position, which is then asserted in the test.
However, when the { read: ElementRef } parameter is set, the mock gets completely ignored by the TestBed, even though it's being added in the declarations array. If I remove { read: ElementRef }, the mock is used in the test and it passes. But then my application doesn't work, as it is now getting the component reference, where the nativeElement property doesn't exist, rather than the element reference.
So how do I get the ElementRef in my application and then in my test use the mock component?

I have fixed this by changing the architecture of the app. The child component now finds it's own offsetLeft property, and then puts it into an output EventEmitter to be picked up the parent component.
export class ChildComponent implements AfterViewInit {
#Output() offsetPosition: EventEmitter<number> = new EventEmitter<number>();
constructor(private el: ElementRef) {}
public ngAfterViewInit() {
this.offsetPosition.emit(this.el.nativeElement.offsetLeft);
}
}
export class ParentComponent implements AfterViewInit {
public childComponentOffset: number;
public ngAfterViewInit() {
setTimeout(() => {
// this.childComponentOffset is available
// needs to be in setTimeout to prevent ExpressionChangedAfterItHasBeenCheckedError
// more info: https://blog.angularindepth.com/everything-you-need-to-know-about-the-expressionchangedafterithasbeencheckederror-error-e3fd9ce7dbb4
}
}
public getChildComponentOffset(position: number): void {
this.childComponentOffset = position;
}
}
And then in the HTML, you just define the child component with output variable and method:
<child-component (offsetPosition)="getChildComponentOffset($event)"></child-component>
In the test, I then mock ElementRef for the child component and use it as a provider.
const mockElementRef: any = {
get offsetLeft() {
return position;
}
};
beforeEach(async(() => TestBed.configureTestingModule({
imports: [ ... ],
declarations: [ ParentComponent ],
providers: [
{ provide: ElementRef, useValue: mockElementRef }
],
schemas: [ NO_ERRORS_SCHEMA ]
}).compileComponents()));
it('should have the correct position, based on position of child-component', (done) => {
component.getChildComponentOffset(600);
setTimeout(() => expect(component.position).toBe('left'));
done();
});

Related

ngOnInit and MediaChange testing with Karma

I am trying to test the code in the ngOnInit method. The code watches for change in screen size for a navigation bar to resize down to mobile or to stay as a top bar. I have tried a for about a week and keep getting a slew of different errors when I test. I have left out some code for comp.component.ts as the other code is not necessary for this. I keep getting subscribe is not a method or Can't resolve all parameters for MediaChange: (?, ?, ?, ?). Any advice on how I can achieve writing a test for this or any resources you might suggest looking at to help me figure this out.
comp.component.ts
import { Component, OnInit } from '#angular/core';
import { Subscription } from 'rxjs';
import { MediaChange, ObservableMedia } from '#angular/flex-layout';
#Component({
selector: 'app-comp',
templateUrl: './comp.component.html',
styleUrls: ['./comp.component.scss']
})
export class NavigationComponent implements OnInit {
isOpen: Boolean;
watcher: Subscription;
activeMediaQuery = "";
media: ObservableMedia;
constructor() {
this.isOpen = false;
}
ngOnInit(): void {
this.watcher = this.media.subscribe((change: MediaChange) => {
this.activeMediaQuery = change ? `'${change.mqAlias}' = (${change.mediaQuery})` : '';
this.isOpen = false;
});
}
navPressed(event, path): void {
this.navClick.emit(path);
if ( this.checkSize() ) this.toggle();
}
checkSize(): Boolean {
return this.activeMediaQuery.includes('xs') || this.activeMediaQuery.includes('sm');
}
}
comp.component.spec.ts
import { Component } from '#angular/core';
import { ComponentFixture, TestBed } from '#angular/core/testing';
import { DebugElement } from '#angular/core';
import { BrowserAnimationsModule } from '#angular/platform-browser/animations';
import { MatButtonModule, MatToolbarModule, MatIconModule } from '#angular/material';
import { CompComponent } from './comp.component';
import { Subscription } from 'rxjs';
import { MediaChange, ObservableMedia } from '#angular/flex-layout';
#Component({
selector: 'app-test-component-wrapper',
template: '<app-navigation [navItems]="clickables" (navClick)="handleNavClick($event)"></app-navigation>'
})
class TestWrapperComponent {
clickables = [
{ path: '/login', label: 'Login', onClick() {} }
];
}
describe('app testing', () => {
let component: CompComponent;
let fixture: ComponentFixture<TestWrapperComponent>;
beforeEach(async(() => {
TestBed.configureTestingModule({
imports: [
MatButtonModule,
MatToolbarModule,
MatIconModule,
BrowserAnimationsModule
],
declarations: [
TestWrapperComponent,
NavigationComponent
],
providers: [
ObservableMedia,
MediaChange,
Subscription
]
}).compileComponents();
fixture = TestBed.createComponent(TestWrapperComponent);
}));
it('should create and have Login label', () => {
// EDIT START
spyOn(ObservableMedia, 'prototype');
// EDIT END
expect(fixture).toBeTruthy();
fixture.detectChanges();
fixture.whenStable().then(() => {
component = fixture.debugElement.children[0].componentInstance;
expect(component.navItems[0].label).toBe('Login');
});
});
});
EDIT: Added the 'EDIT' comment in the code with the code I have added. I am now getting the resolve all parameters for MediaChange: (?, ?, ?, ?) error which I think is forward progress from the subscribe error mentioned above.
Some observations:
ObservableMedia from flex-layout needs to be injected into your component to work. Details here
You aren't providing MediaChange or Subscription in the original component, so no need to in the TestBed either.
In the stackblitz below I had to make a few assumptions. Let me know if any of these are wrong, or just go ahead and update the stackblitz:
In your spec you imported CompComponent, but in comp.component.ts you defined NavigationComponent. Of the two I chose to use NavigationComponent.
navClick was missing from your code above, so I assumed it is an #Output from your component (since you emit a path to it).
navItems was also missing from the code above, but since you are testing it I assumed it was important and guessed it is an input to your component (again, just by the way you were using it).
You didn't include your template, so I mocked it very simply.
toggle was called from within navPressed, but didn't exist so I created it as an empty function.
Here is the stackblitz: https://stackblitz.com/edit/stackoverflow-q-53024049?file=app%2Fmy.component.spec.ts
To fix what you had: I made the changes above and mocked the ObservableMedia object passed in with the following:
let mockFlex = jasmine.createSpyObj({
subscribe: ({mqAlias: 'xs', mediaQuery: ''}),
isActive: true,
});
I also changed the providers array to the following:
providers: [
{ provide: ObservableMedia, useValue: mockFlex }
]
Check the stackblitz for all the details. As you can see there, the test now passes.

Pass changing array to child component #Input field

I am trying to pass an array to a child component. The array is being defined in the subscribe method of a parent component's onInit lifecycle hook.
Parent component:
import { Component, OnInit } from '#angular/core';
#Component({
selector: 'selector-parent',
templateUrl: 'parent.component.html'
})
export class ParentComponent implements OnInit {
array: [];
constructor() { }
ngOnInit() {
this.appDataService.getValues()
.subscribe(
value => {
value.item
.filter(loaded => !this.array.some(existing => existing.key === loaded.key))
.forEach(loaded => { this.array.push(loaded) })
}
)
}
}
Child component:
import { Component, OnInit } from '#angular/core';
#Component({
selector: '[selector-child]',
templateUrl: 'child.component.html'
})
export class ChildComponent implements OnInit {
#Input() inputArray: [];
constructor() { }
ngOnInit() {
console.log(this.inputArray)
}
}
Binding is: <tr selector-child [inputArray]="array"></tr>
Unfortunately, the console log on the inputArray is turning up undefined. I've tried using ngOnChanges in the child component but for some reason, it won't recognize the change in the parent. Thinking of using a service to pass the data if there isn't a simpler way to solve the problem.
You have to initialize the array in your parent component:
array: [] = [];
I don't see ngOnChanges in your child component. Also, make sure you do it as how it specified in the angular docs. https://angular.io/guide/component-interaction#intercept-input-property-changes-with-ngonchanges

angular: How to mock extends class in unit test

I've a injectable service (EntityApi) which extends a class (BaseApi). In my spec I like to mock the BaseApi with BaseApiStub. But it vain. Always calling the EntityApi.
// class
export class BaseApi { // want to mock BaseApi
constructor(injector: Injector) {
console.log("Should not be here...");
}
}
// service
#Injectable()
export class EntityApi extends BaseApi {
constructor(injector: Injector) {
super(injector, "entity");
}
}
// component
#Component({
selector: 'rt-entity-list',
templateUrl: './entity-list.component.html',
})
export class EntityListComponent {
api: any;
constructor(public entityApi: EntityApi) {
this.api = entityApi;
}
}
// mock api
export class BaseApiStub { //mocked api
constructor() {
console.log("You are on track!!")
}
get() { }
}
// spec
describe('EntityListComponent', () => {
let component: EntityListComponent;
let fixture: ComponentFixture<EntityListComponent>;
beforeEach(async(() => {
TestBed.configureTestingModule({
declarations: [EntityListComponent],
providers: [ { provide: BaseApi, useClass: BaseApiStub }, // mocked class.
],
schemas: [NO_ERRORS_SCHEMA]
}).compileComponents();
beforeEach(() => {
fixture = TestBed.createComponent(EntityListComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should create', () => {
expect(component).toBeTruthy();
});
});
Expected Behavior is, while compile component in spec. It should call the BaseApiStub, instead it is calling BaseApi. I've seen a solution as below. But no luck.
export class BaseApiStub extends BaseApi { }
Test Code: stackblitz Check the console. I expect the You are
on track!! log but received as Should not be here...
Not able to progress further. Can someone correct my mistake please.
What you are trying to do does not work. Dependency injection and class inheritance are not directly related. This means you cannot switch out the base class of your service like this.
As I see it you have two ways on how to do this.
Option 1:
Instead of mocking your BaseApi and providing the mock in your test you need to mock your EntityApi and provide this mock in your test.
Option 2:
Instead of letting your EntityApi extend from BaseApi, you could keep BaseApi a simple service and provide it as a dependency.
Instead of
class EntityApi extends BaseApi {
constructor(private injector: Injector) {
you do
class EntityApi {
constructor(private api: BaseApi) {
If you setup your EntityApi like this, it does not extend from BaseApi, but rather has it as a dependency. Then you can create a mock of the BaseApi and provide it like you did in your test.
Edit
Regarding your comment:
Since I should be using methods from BaseApi I cannot go without extends.
This is not true. Let's say the BaseApi has a method foo() that you want to use. When you extend your baseclass, the usage might look like this:
class EntityApi extends BaseApi {
constructor(private injector: Injector) {}
exampleMethod() {
this.foo();
}
}
If you just have the dependency you can still call the method like this:
class EntityApi {
constructor(private api: BaseApi) {}
exampleMethod() {
this.api.foo();
}
}
You don't need to extend from BaseApi in order to call methods on it.
In case you need to mock a method of a parent class (e.g for Directive) you can do that through the stub extension of the tested class.
spyObject = {
methodToSpyOn(){}
};
#Directive({selector: '[myDirective]'})
class MyStubDirective extends MyDirective {
parentMethodToMock() {
return spyObject.methodToSpyOn();
}
}
spyOn(spyObject, 'methodToSpyOn').and.returnValue(true);
This approach is usually needed if your class has the parent method calls in constructor

Angular2 custom ErrorHandler, why can I log to console but not to template?

I would like to have custom errors in my Angular2 app. Thus I have extended ErrorHandler in my component:
import { Component, ErrorHandler, OnInit } from '#angular/core';
import { GenericError } from './generic-error.component';
#Component({
selector: 'custom-error-handler',
templateUrl: 'app/error-handler/custom-error-handler.component.html?' + +new Date()
})
export class CustomErrorHandler extends ErrorHandler {
errorText: string;
constructor() {
super(false);
}
ngOnInit() {
this.errorText = 'Initial text!';
}
public handleError(error: any): void {
if (error.originalError instanceof GenericError) {
console.info('This is printed to console!');
this.errorText = "I want it to print this in the template!";
}
else {
super.handleError(error);
}
}
}
My template simply contains:
<span style="color:red">{{errorText}}</span>
First I see "Initial text!" in the template as set in ngOnInit. That's as expected.
I can then throw a new exception like this from a different component:
throw new GenericError();
and it hits the code with handleError and prints to console but it doesn't update my template errorText with:
"I want it to print this in the template!"
It's like it ignores my template, when inside the handleError function.
What could be the problem here?
* ADDED MORE INFORMATION *
I thought I should add some more information. So here is the module I made for CustomErrorHandler (maybe the problem is with the providers?):
import { NgModule, ErrorHandler } from '#angular/core';
import { CommonModule } from '#angular/common';
import { CustomErrorHandler } from './custom-error-handler.component';
#NgModule({
declarations: [
CustomErrorHandler
],
imports: [
CommonModule
],
exports: [
CustomErrorHandler
],
providers: [
{ provide: ErrorHandler, useClass: CustomErrorHandler }
]
})
export class CustomErrorModule { }
There is indeed only one instance of the CustomErrorHandler (I checked with the Augury Chrome plugin).
For completeness, here is is the GenericError component:
export class GenericError {
toString() {
return "Here is a generic error message";
}
}
The solution was to add a service as suggested in the question's comment track. This way I can set the property in the component and eventually show it in the template.
I created the service, so that it has a function which takes one parameter. Injected the service, call the service's function from the handleError in the component function, and send the text I want in the template as the parameter. Then I use an observable, to get the text back to the component.
In the constructor of the component, I added this observer.
let whatever = this.cs.nameChange.subscribe((value) => {
setTimeout(() => this.errorText = value);
});
I needed to add the setTimeout, or else it would not update the template before the second time the observable was changed.
Phew! The Angular team should make this global exception handling easier in future releases.

Angular 2 access parent routeparams from child component [duplicate]

How do I get the RouteParams from a parent component?
App.ts:
#Component({
...
})
#RouteConfig([
{path: '/', component: HomeComponent, as: 'Home'},
{path: '/:username/...', component: ParentComponent, as: 'Parent'}
])
export class HomeComponent {
...
}
And then, in the ParentComponent, I can easily get my username param and set the child routes.
Parent.ts:
#Component({
...
})
#RouteConfig([
{ path: '/child-1', component: ChildOneComponent, as: 'ChildOne' },
{ path: '/child-2', component: ChildTwoComponent, as: 'ChildTwo' }
])
export class ParentComponent {
public username: string;
constructor(
public params: RouteParams
) {
this.username = params.get('username');
}
...
}
But then, how can I get this same 'username' parameter in those child components? Doing the same trick as above, doesn't do it. Because those params are defined at the ProfileComponent or something??
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(
public params: RouteParams
) {
this.username = params.get('username');
// returns null
}
...
}
UPDATE:
Now that Angular2 final was officially released, the correct way to do this is the following:
export class ChildComponent {
private sub: any;
private parentRouteId: number;
constructor(private route: ActivatedRoute) { }
ngOnInit() {
this.sub = this.route.parent.params.subscribe(params => {
this.parentRouteId = +params["id"];
});
}
ngOnDestroy() {
this.sub.unsubscribe();
}
}
ORIGINAL:
Here is how i did it using the "#angular/router": "3.0.0-alpha.6" package:
export class ChildComponent {
private sub: any;
private parentRouteId: number;
constructor(
private router: Router,
private route: ActivatedRoute) {
}
ngOnInit() {
this.sub = this.router.routerState.parent(this.route).params.subscribe(params => {
this.parentRouteId = +params["id"];
});
}
ngOnDestroy() {
this.sub.unsubscribe();
}
}
In this example the route has the following format: /parent/:id/child/:childid
export const routes: RouterConfig = [
{
path: '/parent/:id',
component: ParentComponent,
children: [
{ path: '/child/:childid', component: ChildComponent }]
}
];
You shouldn't try to use RouteParams in your ChildOneComponent.
Use RouteRegistry, instead!
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(registry: RouteRegistry, location: Location) {
route_registry.recognize(location.path(), []).then((instruction) => {
console.log(instruction.component.params['username']);
})
}
...
}
UPDATE: As from this pull request (angular beta.9): https://github.com/angular/angular/pull/7163
You can now access to the current instruction without recognize(location.path(), []).
Example:
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(_router: Router) {
let instruction = _router.currentInstruction();
this.username = instruction.component.params['username'];
}
...
}
I haven't tried it, yet
Further details here:
https://github.com/angular/angular/blob/master/CHANGELOG.md#200-beta9-2016-03-09
https://angular.io/docs/ts/latest/api/router/Router-class.html
UPDATE 2:
A small change as from angular 2.0.0.beta15:
Now currentInstruction is not a function anymore. Moreover, you have to load the root router. (thanks to #Lxrd-AJ for reporting)
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(_router: Router) {
let instruction = _router.root.currentInstruction;
this.username = instruction.component.params['username'];
}
...
}
As mentioned by Günter Zöchbauer, I used the comment at https://github.com/angular/angular/issues/6204#issuecomment-173273143 to address my problem. I used the Injector class from angular2/core to fetch the routeparams of the parent. Turns out angular 2 does not handle deeply nested routes. Maybe they'll add that in the future.
constructor(private _issueService: IssueService,
private _injector: Injector) {}
getIssues() {
let id = this._injector.parent.parent.get(RouteParams).get('id');
this._issueService.getIssues(id).then(issues => this.issues = issues);
}
I found an ugly but working solution, by requesting the parent (precisely the 2nd ancestor) injector, and by getting the RouteParams from here.
Something like
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(injector: Injector) {
let params = injector.parent.parent.get(RouteParams);
this.username = params.get('username');
}
}
RC5 + #angular/router": "3.0.0-rc.1 SOLUTION: It seems that this.router.routerState.queryParams has been deprecated. You can get the parent route params this way:
constructor(private activatedRoute: ActivatedRoute) {
}
this.activatedRoute.parent.params.subscribe(
(param: any) => {
let userId = param['userId'];
console.log(userId);
});
You can take component of parent route inside of child component from injector and then get any from child component. In you case like this
#Component({
...
})
export class ChildOneComponent {
public username: string;
constructor(
public params: RouteParams
private _injector: Injector
) {
var parentComponent = this._injector.get(ParentComponent)
this.username = parentComponent.username;
//or
this.username = parentComponent.params.get('username');
}
...
}
Passing Injector instance to constructor in child component may not be good if you want to write unit tests for your code.
The easiest way to work around this is to have a service class in the parent component, in which you save your required params.
#Component({
template: `<div><router-outlet></router-outlet></div>`,
directives: [RouterOutlet],
providers: [SomeServiceClass]
})
#RouteConfig([
{path: "/", name: "IssueList", component: IssueListComponent, useAsDefault: true}
])
class IssueMountComponent {
constructor(routeParams: RouteParams, someService: SomeServiceClass) {
someService.id = routeParams.get('id');
}
}
Then you just inject the same service to child components and access the params.
#Component({
template: `some template here`
})
class IssueListComponent implements OnInit {
issues: Issue[];
constructor(private someService: SomeServiceClass) {}
getIssues() {
let id = this.someService.id;
// do your magic here
}
ngOnInit() {
this.getIssues();
}
}
Note that you should scope such service to your parent component and its child components using "providers" in parent component decorator.
I recommend this article about DI and scopes in Angular 2: http://blog.thoughtram.io/angular/2015/08/20/host-and-visibility-in-angular-2-dependency-injection.html
In RC6, router 3.0.0-rc.2 (probably works in RC5 as well), you can take route params from the URL as a snapshot in case that params won't change, without observables with this one liner:
this.route.snapshot.parent.params['username'];
Don't forget to inject ActivatedRoute as follows:
constructor(private route: ActivatedRoute) {};
With RxJS's Observable.combineLatest, we can get something close to the idiomatic params handling:
import 'rxjs/add/operator/combineLatest';
import {Component} from '#angular/core';
import {ActivatedRoute, Params} from '#angular/router';
import {Observable} from 'rxjs/Observable';
#Component({ /* ... */ })
export class SomeChildComponent {
email: string;
id: string;
constructor(private route: ActivatedRoute) {}
ngOnInit() {
Observable.combineLatest(this.route.params, this.route.parent.params)
.forEach((params: Params[]) => {
this.id = params[0]['id'];
this.email = params[1]['email'];
});
}
}
I ended up writing this kind of hack for Angular 2 rc.1
import { Router } from '#angular/router-deprecated';
import * as _ from 'lodash';
interface ParameterObject {
[key: string]: any[];
};
/**
* Traverse route.parent links until root router and check each level
* currentInstruction and group parameters to single object.
*
* e.g.
* {
* id: [314, 593],
* otherParam: [9]
* }
*/
export default function mergeRouteParams(router: Router): ParameterObject {
let mergedParameters: ParameterObject = {};
while (router) {
let currentInstruction = router.currentInstruction;
if (currentInstruction) {
let currentParams = currentInstruction.component.params;
_.each(currentParams, (value, key) => {
let valuesForKey = mergedParameters[key] || [];
valuesForKey.unshift(value);
mergedParameters[key] = valuesForKey;
});
}
router = router.parent;
}
return mergedParameters;
}
Now in view I collect parameters in view instead of reading RouteParams I just get them through router:
#Component({
...
})
export class ChildishComponent {
constructor(router: Router) {
let allParams = mergeRouteParams(router);
let parentRouteId = allParams['id'][0];
let childRouteId = allParams['id'][1];
let otherRandomParam = allParams.otherRandomParam[0];
}
...
}
In FINAL with little help of RXJS you can combine both maps (from child and parent):
(route) => Observable
.zip(route.params, route.parent.params)
.map(data => Object.assign({}, data[0], data[1]))
Other questions one might have:
Is it really a good idea to use above - because of coupling (couple child component with parent's param's - not on api level - hidden coupling),
Is it proper approach in term of RXJS (it would require hardcore RXJS user feedback ;)
You can do it on the snapshot with the following, but if it changes, your id property will not be updated.
This example also shows how you can subscribe to all ancestor parameter changes and look for the one you are interested in by merging all of the parameter observables. However, be careful with this method because there could be multiple ancestors that have the same parameter key/name.
import { Component } from '#angular/core';
import { ActivatedRoute, Params, ActivatedRouteSnapshot } from '#angular/router';
import { Observable } from 'rxjs/Observable';
import { Subscription } from 'rxjs/Subscription';
import 'rxjs/add/observable/merge';
// This traverses the route, following ancestors, looking for the parameter.
function getParam(route: ActivatedRouteSnapshot, key: string): any {
if (route != null) {
let param = route.params[key];
if (param === undefined) {
return getParam(route.parent, key);
} else {
return param;
}
} else {
return undefined;
}
}
#Component({ /* ... */ })
export class SomeChildComponent {
id: string;
private _parameterSubscription: Subscription;
constructor(private route: ActivatedRoute) {
}
ngOnInit() {
// There is no need to do this if you subscribe to parameter changes like below.
this.id = getParam(this.route.snapshot, 'id');
let paramObservables: Observable<Params>[] =
this.route.pathFromRoot.map(route => route.params);
this._parametersSubscription =
Observable.merge(...paramObservables).subscribe((params: Params) => {
if ('id' in params) {
// If there are ancestor routes that have used
// the same parameter name, they will conflict!
this.id = params['id'];
}
});
}
ngOnDestroy() {
this._parameterSubscription.unsubscribe();
}
}
Getting RouteParams from parent component in Angular 8 -
I have a route http://localhost:4200/partner/student-profile/1234/info
Parent route - student-profile
Param - 1234 (student_id)
Child route - info
Accessing param in child route (info) -
Import
import { ActivatedRoute, Router, ParamMap } from '#angular/router';
Constructor
constructor(private activatedRoute: ActivatedRoute, private router: Router) { }
Accessing parent route params
this.activatedRoute.parent.paramMap.subscribe((params: ParamMap) => this.studentId = (params.get('student_id')));
Now, our variable studentId has the param value.

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