I'm trying to make two angular components and I want to call a function from the first component in the second component. When I try this I get following error message: Cannot red property 'functionName' of undefined
. How can this be solved?
Here a link of an example: https://stackblitz.com/edit/angular-rre4gb
That's because the component you want to call its function, is not instantiated.
for component communication you can use a service
instead:
@Injectable()
export class MyService {
myCustomFunction(){
}
}
in your component:
@Component({
selector: 'my-component',
providers: [ MyService ]
})
export class MyComponent {
// inject your service to make it available
constructor(private service: MyService){}
doStuff(){
// call function which is located in your service
this.service.myCustomFunction();
}
}
As others have stated, I would prefer a shared service with a Subject
among these components.
service :
@Injectable()
export class SharedService {
mySubject = new Subject();
}
WorldComponent (subscriber):
export class WorldComponent {
constructor(private sharedService: SharedService){
this.sharedService.mySubject.subscribe((data)=>{
this.worldFunction();
})
}
HelloComponent (publisher):
public helloFunction() {
alert('Hello');
this.sharedService.mySubject.next(true);
}
You can find the updated example here: https://stackblitz.com/edit/angular-rnvmkq?file=app%2Fworld.component.ts
The best way to share information between multiple components is generally through a service.
Create a separate file: file.service.ts
Provide the service in the app.module.ts file
Inject the service into each component. Then you'll have access to the variables in both components
See this: https://angular.io/tutorial/toh-pt4
错误的原因是,hello组件未导入,但您不应在其他组件之间调用服务,而应从其他组件调用组件,就像已经提出的其他答案一样。
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