React useReducer not updating state

Question

I'm using useReducer to update the errorsState when user logged in and failed. I've read many solutions and it was said that dispatch is async and I know that so I put console.log inside the useEffect to see the errorsState change, but unfortunately it didn't changed. Here's my code

Login.jsx

export default function Login({ userProps }) {
  //
  // some variables and state
  //
  const { loading, user } = useLogin({ email: state.email }, state.submitted)
  const [errors, dispatch] = useReducer(errorsReducer, errorsState)

  useEffect(() => {
    console.log("errors", errors) // it won't triggered because errors state didn't updating from UseLogin
  }, [errors])

  return content
}

Here is fetch function useLogin

AuthAction.js

export const useLogin = (data, submitted) => {
  const [state, dispatch] = useReducer(userReducer, userState)
  const [errors, errorsDispatch] = useReducer(errorsReducer, errorsState)

  useEffect(() => {
    if (!submitted) return

    dispatch({
      type: USER_ACTIONS.MAKE_REQUEST,
    })

    ticketApi.login(data).then(({ res, status }) => {
      if (status !== "failed") {
        // Save to local storage
        const { token } = res
        // set token to local storage
        localStorage.setItem("jwtToken", token)
        // Set token to Auth Header
        setAuthToken(token)
        // decode token to get user data with jwt-decode
        const decoded = jwt_decode(token)
        // set current user
        return dispatch({
          type: USER_ACTIONS.GET_USER,
          payload: decoded,
        })
      }

      dispatch({
        type: USER_ACTIONS.END_REQUEST,
      })

      return errorsDispatch({
        type: ERRORS_ACTIONS.GET_ERRORS,
        payload: res.response.data,
      })
    })
  }, [submitted])

  return state
}

I've tried put console.log inside the ERRORS_ACTIONS.GET_ERRORS to see the response, and it was fine. So where did i go wrong?

Answer 1

useReducer allows you to better manage complex states, it's not a state container, what you're doing there is to create 2 different states, one inside useLogin and the other in your Login component, return errors from your useLogin hook so the Login component can see it.

Login

export default function Login({ userProps }) {
  //
  // some variables and state
  //
  const { loading, user, errors } = useLogin({ email: state.email }, state.submitted)

  useEffect(() => {
    console.log("errors", errors)
  }, [errors])

  return content
}

useLogin

export const useLogin = (data, submitted) => {
  const [state, dispatch] = useReducer(userReducer, userState)
  const [errors, errorsDispatch] = useReducer(errorsReducer, errorsState)

  useEffect(() => {
    if (!submitted) return

    dispatch({
      type: USER_ACTIONS.MAKE_REQUEST,
    })

    ticketApi.login(data).then(({ res, status }) => {
      if (status !== "failed") {
        // Save to local storage
        const { token } = res
        // set token to local storage
        localStorage.setItem("jwtToken", token)
        // Set token to Auth Header
        setAuthToken(token)
        // decode token to get user data with jwt-decode
        const decoded = jwt_decode(token)
        // set current user
        return dispatch({
          type: USER_ACTIONS.GET_USER,
          payload: decoded,
        })
      }

      dispatch({
        type: USER_ACTIONS.END_REQUEST,
      })

      return errorsDispatch({
        type: ERRORS_ACTIONS.GET_ERRORS,
        payload: res.response.data,
      })
    })
  }, [submitted])

  return { ...state, errors };
}