javascript - 类型 'Observable<void>' 不可分配给类型 'void | Action | Observable<Action>' 。添加效果时

Question

“run”在添加效果时出错。也尝试过手动返回字符串、数字等，但不起作用。

效果代码:

@Effect() 
getRoles$: Observable<Roles[]> = this.dataPersistence.fetch(CreateActionTypes.GetRoles, {
    run: (action: GetRoles) => {

       return this.formService
         .getRoles()
         .pipe(map(roles => {
           return new RolesLoaded(roles);
          }));
    },
    onError: (action: GetRoles, error) => {
      console.error(error);
      return new RolesLoadError(error);
    }
  });

错误消息:

ERROR in apps/app/src/app/+state/create.effects.ts(32,5):

error TS2322:
Type '(action: GetRoles) => Observable' is not assignable to type '(a: GetRoles, state?: CreatePartialState) => void | Action | Observable'.
Type 'Observable' is not assignable to type 'void | Action | Observable'.

Answer 1

@Effect应该返回一个Action的可观察值，而不是Action[]，而只是Action。

就您而言，这似乎是多个概念之间的混合。

这是@Effect的示例

  createProject$ = createEffect(() => this.actions$.pipe(
    ofType(CREATE_PROJECT),
    switchMap(({ name, id }) => this.myService.createProject(name, id).pipe(
      concatMap(project => [
        CREATE_PROJECT_SUCCESS(project),
        NAVIGATE({ path: ['foo', project.id] })
      ]),
      catchHttpError()
    )),
  ));