Angular2 trigger function when observable property changes

Question

I use a workingData service that holds data that permeates my application. It returns an observable to the Mock workingData object.

@Injectable()
export class WorkingDataService {
  getWorkingData(): Observable<WorkingData> {
    return Observable.of(WORKINGDATA);
  }
  getSelectedDate(): Observable<Date> {
    return Observable.of(WORKINGDATA.selectedDate);
  }
}

One property on the workingData object is a date field called selectedDate.

export const WORKINGDATA: WorkingData = {
  today: new Date(),
  selectedDate: new Date('11-15-2016'),
  targetDate: new Date(),
  data: []
};

This value can be updated by clicking the "previous month" or "next month" buttons:

This triggers the following function (or it's incrementDate() counterpart) in the cal-nav component:

decrementDate(): void {
  let newDate = new Date(this.workingData.selectedDate.getDate());
  newDate.setMonth(newDate.getMonth() - 1);
  this.workingData.monthPrior = newDate;
}

The observable updates the view in all comopnents in which the workingDate service is injected, but I now need to trigger a funtion in the month component (which is a sibling of the cal-nav component). How trigger a function in the month componenet each time workingData.selectedDate is updated, even if it is updated from a different component?

UPDATE: I now subscribe to the selectedDate property seperately.

ngOnInit(): void {
  this.getWorkingData();
  this.getSelectedDate(); // Just added
}

getSelectedDate(): void{
  this._workingDataService.getSelectedDate().subscribe(selectedDate => {this.myFunc();});
}
myFunc(){
  console.log('working');
}

This fires myFunc() oninit but not when the the value updates.

Answer 1

You can just subscribe to your Observable in your code

this.myObservable.subscribe( data => {
  myFunction();
 });

If that does not fulfil your needs then you have to provide more code or some sequence of what you exactly need