Console.log returns 'undefined' when trying to update status with fetched data

Question

When I get the data on render or when some dependencies change, it updates to the Redux store correctly, but when I console.log it says 'undefined'.

I am developing a booking system and want to get the number of hours booked on a specified date

/// 在组件渲染时获取数据并尝试使用console.log
     useEffect(() => {
    axios
      .get(
        `http://localhost/healthboyz/index.php/booked/${
          formData.doctor_id
        }/${moment(formData.date).format('YYYY-MM-DD')}`
      )
      .then((res) => setBookedHrs(res.data))
      .then(() => console.log(bookedHrs))
      .catch((e) => console.log(e));}, 
    [formData.doctor_id, formData.date]);

/// Hours reducer 
 const hoursReducerDefaultState: {
  bookedHrs: string[];
} = {
  bookedHrs: [],
};

export const hoursReducer = (
  state = hoursReducerDefaultState,
  action: {
    type: string;
    data: string[];
  }
) => {
  switch (action.type) {
    case 'SET_BOOKED_HRS':
      return [...action.data];
    default:
      return state;
  }
};

Answer 1

The question here actually has to do with how state is set in Redux:

Assume that hoursReducer is responsible for the entire hoursReducerDefaultState, its code is as follows:

type HoursReducer = {
  bookedHrs: string[];
};

 const hoursReducerDefaultState: HoursReducer = {
  bookedHrs: [],
};

Then you need to set the Redux state to the state you want to update:

export const hoursReducer = (
  state = hoursReducerDefaultState,
  action: {
    type: string;
    data: string[];
  }
) => {
  switch (action.type) {
    case 'SET_BOOKED_HRS':
      // 使用“spread”操作符包括先前的状态
      return {
        ...state,
        bookedHrs: action.data
      }
    default:
      return state;
  }
};

Note: I'm also assuming you want to completely replace the value of bookedHrs.