无法使用共享服务在Angular 2组件之间传递数据

Question

I am passing info from a read component to an edit component. I used a shared service ( modeled off of this post ) but in the child component the Employee info is null. I think maybe I am unintentionally instantiating the service twice which is why it's empty (?) but not sure where I am doing this. The lines with //undefined should have the same employee info as the parent (parent is working)

Parent

@Component({
    providers: [EmployeesService]
})

export class EmployeeParentComponent {
    private employee: Employee;

    constructor(
        private employeesService: EmployeesService,
        protected router: Router,
        protected route: ActivatedRoute,) { }

    ngOnInit(): void {

    }
//called from HTML template on Edit button click
    toggleEditMode(employee: Employee) {
        this.employeesService.employee = employee;
        alert(this.employeesService.employee.firstName); //correct name
        this.router.navigate('/editPage')
    }
}

Child

@Component({
    providers: []
})

export class EditEmployeeComponent {
    constructor(
        private employeesService: EmployeesService
        ) {
        console.info(employeesService.employee); //undefined
    }

    ngOnInit(): void {
        console.info(this.employeesService.employee); //undefined
    }
}

Service

@Injectable()
export class EmployeesService {
    public employee: Employee;
}

Answer 1

The reason is that service instance provided by specific component(you are doing right now) can not be accessed by another component.

If you want to use a service as a singleton, you should provide it at your @NgModule 's providers array.

So just remove EmployeesService from provider array of EmployeeParentComponent and add it to your @NgModule 's providers array