Question

我正在尝试让NgRX效果返回一个动作对象。动作对象表示“成功”，并且需要返回所有检索到的机构作为有效负载的一部分。我该怎么做呢？请注意，mergeMap内部的块不起作用。检索它们后，我需要将所有检索到的机构作为有效载荷的一部分返回。

  @Effect()
  getInstitutions$ = this.actions$
    .ofType(institutionActions.InstitutionActionTypes.GetInstitutions)
    .pipe(
      switchMap(() => {
        const institutions = this.getInstitutions();
        console.log(institutions);
        return this.getInstitutions();
      }),
      mergeMap((institutions: Institution[]) => {
        // return institutions;
        return {
          type: institutionActions.InstitutionActionTypes.GetInstitutionsSuccess,
          payload: institutions
        };
      })
    );

Answer 1

您必须像下面这样对this.getInstitutions()进行操作：

@Effect()
getInstitutions$ = this.actions$
  .ofType(institutionActions.InstitutionActionTypes.GetInstitutions)
  .pipe(
    switchMap(() => {
      return this.getInstitutions().pipe(
        map(institutions => ({
          type: institutionActions.InstitutionActionTypes.GetInstitutionsSuccess,
          payload: institutions
        })),
        catchError(_ => ...) //don't forget to handle errors
      )
    })
  );

作为旁注，我鼓励您使用动作创建者，而不是“在整个地方”创建动作对象-Let’s have a chat about Actions and Action Creators within NgRx

Answer 2

如何使用“地图”内置的mergeMap。您可以尝试关注吗？

 @Effect()
  getInstitutions$ = this.actions$
    .ofType(institutionActions.InstitutionActionTypes.GetInstitutions)
    .pipe(
      switchMap(() => {
        const institutions = this.getInstitutions();
        console.log(institutions);
        return this.getInstitutions();
      }),
      map((institutions: Institution[]) => {
        // return institutions;
        return {
          type: institutionActions.InstitutionActionTypes.GetInstitutionsSuccess,
          payload: institutions
        };
      })
    );

希望有帮助！

RxJS返回带有数组有效载荷的新对象

2 个答案: