The Observable becomes null upon invocation of the unsubscribe function

Seeking assistance in creating an observable that retrieves data in a specific format.

getRootGroupNodes(): Observable<Group[]> {
    return Observable.create(function(observer) {
        var groups = [
            { groupName: "Group1" },
            { groupName: "Group2" }
        ]
        observer.next(groups);
        observer.complete();
    });
}

Encountering issues when attempting to use it

this._loadGroupsSubscription = this._apiGroupService.getRootGroupNodes()
    .retry(3)
    .subscribe(
    groups => {
        // manipulate retrieved groups
    },
    err => { this._log.logMessage("failed to retrieve groups"); },
    () => {
        this._loadGroupsSubscription.unsubscribe();
    }
);

Observing that this._loadGroupsSubscription is returning as null, resulting in an error when trying to unsubscribe from it. Any insights on what could be causing this issue? It seems like a fundamental aspect..

Answer â„–1

Indeed, the variable remains unassigned within the callback function. There are a couple of approaches to address this issue:

  1. Enclose the unsubscription process with setTimeout():

    setTimeout(() => _loadGroupsSubscription.unsubscribe());
    
  2. Introduce the .delay(0) operator as an alternative solution:

    var _loadGroupsSubscription = getRootGroupNodes()
      .retry(3)
      .delay(0)
      .subscribe(
        groups => {
          console.log(groups);
        },
        err => { this._log.logMessage("failed to retrieve groups"); },
        () => {
          _loadGroupsSubscription.unsubscribe();
        }
    );
    

Check out the live demonstration here: https://example.com/demo

For a similar question and detailed explanation on how this concept functions, refer to this resource: Other operator in calculation chain than combineLatest to avoid redundant calculations

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