I am following 2nd example from this site: https://www.agiratech.com/how-to-prevent-memory-leaks-in-angular-observables/
I would like to know if I have multiple Observables in a component, do I need to create that many references to the Subject object. I have used unsubscribe and unsubscribe1 variables. Should I be re-using unsubscribe in different methods, or create new Subject instance for each time I subscribe? Code did not throw error in either case.
Here is my code:
import { Component, OnDestroy, OnInit } from '@angular/core';
import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';
import { ProjDetailsService } from '../../services/proj-details.service';
@Component({
selector: 'app-proj-details',
templateUrl: './proj-details.component.html',
styleUrls: ['./proj-details.component.scss']
})
export class ProjDetailsComponent implements OnInit {
private unsubscribe = new Subject();
private unsubscribe1 = new Subject();//is this required?
constructor(public _projDetailsService: ProjDetailsService
) {
}
ngOnInit() {
this.LoadApprovalManager();
this.LoadActiveProjectSubmissions();
}
public LoadApprovalManager() {
this._projDetailsService.GetDefaultMgrGeidData()
.pipe(takeUntil(this.unsubscribe))
.subscribe(result => {
}, error => {
//this.ErrorMessage('Unable to load search data ' + error.toString());
//this.SelectedApproverManager = '';
});
}
LoadActiveProjectSubmissions() {
this._projDetailsService.GetActiveProjectSubmissions()
.pipe(takeUntil(this.unsubscribe1))
.subscribe(x => {
//processing
}, error => {
// this.ErrorMessage(error.toString());
});
}
ngOnDestroy() {
this.unsubscribe.next();
this.unsubscribe.complete();
this.unsubscribe1.next();
this.unsubscribe1.complete();
}
}
following that example, the answer is no. You would use the same unsubscribe signal for all observables like this:
export class ProjDetailsComponent implements OnInit {
private unsubscribe = new Subject();
constructor(public _projDetailsService: ProjDetailsService
) {
}
ngOnInit() {
this.LoadApprovalManager();
this.LoadActiveProjectSubmissions();
}
public LoadApprovalManager() {
this._projDetailsService.GetDefaultMgrGeidData()
.pipe(takeUntil(this.unsubscribe))
.subscribe(result => {
}, error => {
//this.ErrorMessage('Unable to load search data ' + error.toString());
//this.SelectedApproverManager = '';
});
}
LoadActiveProjectSubmissions() {
this._projDetailsService.GetActiveProjectSubmissions()
.pipe(takeUntil(this.unsubscribe))
.subscribe(x => {
//processing
}, error => {
// this.ErrorMessage(error.toString());
});
}
ngOnDestroy() {
this.unsubscribe.next();
this.unsubscribe.complete();
}
}
However, all due respect to the folks at that site, I think this method makes no sense whatsoever and increases boiler plate code to absurd levels when you could just do this:
export class ProjDetailsComponent implements OnInit {
private subs: Subscription[] = [];
constructor(public _projDetailsService: ProjDetailsService
) {
}
ngOnInit() {
this.LoadApprovalManager();
this.LoadActiveProjectSubmissions();
}
public LoadApprovalManager() {
this.subs.push(this._projDetailsService.GetDefaultMgrGeidData()
.subscribe(result => {
}, error => {
//this.ErrorMessage('Unable to load search data ' + error.toString());
//this.SelectedApproverManager = '';
}));
}
LoadActiveProjectSubmissions() {
this.subs.push(this._projDetailsService.GetActiveProjectSubmissions()
.subscribe(x => {
//processing
}, error => {
// this.ErrorMessage(error.toString());
}));
}
ngOnDestroy() {
this.subs.forEach(s => s.unsubscribe());
}
}
simple uniform approach to subscription management that doesn't pollute your observables with extra steps in the pipe.