javascript - 重新渲染时 react 自定义 Hook 状态不更新

Question

我在使用 react Hook 重新填充表单进行编辑时遇到问题。

父组件:Edit.js

const EditData = (props) => {
    const { Id } = props.match.params;
    const dispatch = useDispatch();
    // calling redux action to get the data
    useEffect(() => {
      dispatch(getDataById(Id));
    }, [Id]);
    const data = useSelector((state) => state.data);
    const initialState = {
      Id: data.cardId || '',
      Number: data.Number || '',
      Date: data.Date,
    };
    //calling custom hook
    const { handleChange, handleSubmit, values,errors } = useForm(
        initialState,// passing initial state to custom hook
        validateOnSubmit,
        submit
    );
    // used to submit the data
    function submit() {
      dispatch(updateCard(values));
    }
    return (<DateForm
            handleSubmit={handleSubmit}
            handleChange={handleChange}
            values={values}
            />);
  };

自定义钩子(Hook):useform.js

  const useForm = (initialState, validateOnSubmit, callback) => {
    const [values, setValues] = useState(initialState);
    const [errors, setErrors] = useState({});
    const [isSubmitting, setIsSubmitting] = useState(false);

    const handleChange = (event) => {
      const { name, value } = event.target;
      setValues({
        ...values,
        [name]: value
      });
    };
    const handleSubmit = (event) => {
      event.preventDefault();
      setErrors(validateOnSubmit(values));
      setIsSubmitting(true);
    };

    useEffect(() => {
      if (Object.keys(errors).length === 0 && isSubmitting) {
        callback();
      }
    }, [errors]);

    return {
      handleChange,
      handleSubmit,
      values,
      errors
    };
  };

当 API 调用完成时，react 重新呈现自定义但 Hook 的本地状态未更新。

const useForm = (initialState, validateOnSubmit, callback) => {
      console.log(initialState);

on second render, here i can receive data from the API

    const [values, setValues] = useState(initialState);

but values is not getting updated, values is still holding the state from the initial render

我想不通这是为什么。我刚开始使用 React Hooks，请帮助我。

Answer 1

正如 OP 在评论中所述:

the initialState variable is updated when the API call get completed,I'm passing that initialState variable to const [values, setValues] = useState(initialState); , so it should update the values variable right?. but it's not!

应该更新状态，初始状态分配一次，直到组件卸载。

参见 useState API , 它在 lazy initialization 中说明:

The initialState argument is the state used during the initial render. In subsequent renders, it is disregarded.