Angular8 RXJS CanDeactivate 在停用前等待可觀察的結果

Question

我正在嘗試使用 CanDeactivate 防護來檢測用戶何時離開組件。 目的是 #1 檢查當前用戶是否擁有記錄上的“正在編輯”鎖，如果是 #2，則調用 observable 來更新數據庫。

我擁有的代碼部分工作，但存在不總是釋放鎖的競爭條件，可能是因為在調用下一個 return 語句時，對this.updateIsBeingEdited$(false)的訂閱並不總是完成。 所以我知道這沒有正確實施。

如何使this.updateIsBeingEdited$ observable 在 canDeactivate 返回值之前完成？

返回值應始終為 true，因為組件應始終停用，它只需要確保this.updateIsBeingEdited$.subscribe()在停用完成之前完成。

零件

  canDeactivate(): Observable<boolean> | boolean {

    // Check if Is Being Edited must be removed
    if (this.mustReleaseIsBeingEdited()) {
      this.removeIsBeingEditedSub = this.updateIsBeingEdited$(false).subscribe(result => {
        // QUESTION: How to wait until this is complete before allowing component to deactivate?
        return true;
      }, err => { console.error(err); }, () => { });

      // Always allow deactivation
      return true;
    } else {
      return true;
    }

  }

  private updateIsBeingEdited$(isBeingEdited): Observable<boolean> {

    const editedObj = {
      _id: this.record._id,
      IsBeingEdited: isBeingEdited,
      EditedBy: this.accessLevelService.getUserId()
    }

    return this.httpService!.postData$(
      `records/_id/${editedObj._id}/IsBeingEdited/`,
      editedObj
    );

  }

警衛

export interface ComponentCanDeactivate {
  canDeactivate: () => boolean | Observable<boolean>;
}
/**
 * Guard to notify client that user has navigated away from route
 * Implemented in component for managing record locks only
 */
@Injectable({
  providedIn: 'root'
})
export class RecordLocksGuard implements CanDeactivate<ComponentCanDeactivate> {
  canDeactivate(component: ComponentCanDeactivate): boolean | Observable<boolean> {
    if (!component) {
      return true;
    }
    component.canDeactivate();
    // Always allow component to deactivate
    return true;
  }
}

Answer 1

謝謝，這是似乎正在工作的更新代碼。

零件

  canDeactivate(): Observable<boolean> | boolean {

    // Check if Is Being Edited must be removed
    if (this.mustReleaseIsBeingEdited()) {
      return this.updateIsBeingEdited$(false);
    } else {
      return of(true);
    }

  }

  private updateIsBeingEdited$(isBeingEdited): Observable<boolean> {

    const editedObj = {
      _id: this.record._id,
      IsBeingEdited: isBeingEdited,
      EditedBy: this.accessLevelService.getUserId()
    }

    return this.httpService!.postData$(
      `records/_id/${editedObj._id}/IsBeingEdited/`,
      editedObj
    );

  }

警衛

export interface ComponentCanDeactivate {
  canDeactivate: () => boolean | Observable<boolean>;
}
/**
 * Guard to notify client that user has navigated away from route
 * Implemented in component for managing record locks only
 */
@Injectable({
  providedIn: 'root'
})
export class RecordLocksGuard implements CanDeactivate<ComponentCanDeactivate> {
  canDeactivate(component: ComponentCanDeactivate): boolean | Observable<boolean> {
    if (!component) {
      return of(true);
    }
    return component.canDeactivate();
  }
}