将结果从分派返回给组件会引发“未定义”异常

Question

bounty到期在6天内。该问题的答案有资格获得+ 50声望赏金。renakre想要引起更多关注对此问题。

我在数据操作tsx文件中具有以下方法：

export function EnrollStudent(student, courseId) {
  return dispatch => {
    dispatch(enrollUserBegin());

    axios
      .post("api/Course/EnrollStudent/" + courseId + "/" + student.id)
      .then(response => {
        if (response.data === 1) {
          dispatch(enrollUserSuccess(student, courseId));

          console.log("Student is enrolled.");
          toast.success("Student is enrolled successfully.", {
            position: toast.POSITION.TOP_CENTER
          });
        } else {
          dispatch(enrollUserSuccess(null, 0));
          console.log("Failed to enroll.");
          toast.warn(
            "Failed to enroll the student. Possible reason: Already enrolled.",
            {
              position: toast.POSITION.TOP_CENTER
            }
          );
        }
      })
      .catch(error => {
        dispatch(enrollUserFailure(error));

        toast.warn("An error occurred. Please contact the Admin.", {
          position: toast.POSITION.TOP_CENTER
        });
      });
  };
}

通过单击按钮从另一个组件调用此方法：

const enroll_onClick = e => {
  e.preventDefault();
  const currentUserId = authenticationService.currentUserValue["id"];
  var student: any = { id: currentUserId };
  props.enrollStudent(student, st_courseId);
};

const mapDispatchToProps = dispatch => {
    return {
            enrollStudent: (student, courseId) => dispatch(EnrollStudent(student, courseId)),
        }
}

export default connect(
    mapStateToProps,
    mapDispatchToProps
)(CourseEnrollmentWithCode);

这很好，并且数据库已正确更新。但是，我想获取enrollStudent的结果并执行一个操作（例如，导航到另一页）。

我尝试了这个，但是收到了props.enrollStudent() is undefined错误。

props.enrollStudent(student, st_courseId)
.then(() => {
    console.log("enrolld");
    history.push('/courses');
 });

有什么建议吗？

Answer 1

您不得在动作创建者中使用承诺 ...您只能返回动作对象... https://redux.js.org/api/store/

在这种情况下（副作用）您必须使用中间件（[redux-thunk，redux-promise，redux-saga）... https://redux.js.org/api/applymiddleware/

如果未使用中间件...当前行为（看起来部分起作用）是至少误导。