useState返回初始值而不是更新值

Question

我强制下面的代码在catch块中运行，它将getFoodCategoriesFailed设置为true，之后当它转到最终块时，它仍然将getFoodCategoriesFailed显示为false，这是它的初始值。有人能指出我做错了什么并帮我改正吗。

const [getFoodCategoriesFailed, setGetFoodCategoriesFailed] = useState(false);

const getCategories = async (url) => {
  const { request } = await requestor.get({ url });

  request.then((response) => {
    setFoodCategories(response);
    setGetFoodCategoriesFailed(false);
  }).catch(() => {
    setFoodCategories(undefined);
    setGetFoodCategoriesFailed(true);
  }).finally(() => {
    onFoodCategoriesRetrieved(getFoodCategoriesFailed, foodCategories?.food_categories);
  });
};

useEffect(() => {
  const url = "xyz";
  getCategories(url);
}, [foodCategories]);

Answer 1

我不是专家，所以如果这没有帮助，我很抱歉，但是...有几件事我可能会尝试：

>

类似的东西：

const getCategories = async (url) => {
  const { request } = await requestor.get({ url });
  let localFoodCategories = undefined;
  let localGetFoodCategoriesFailed = true;
  
  request.then((response) => {
    localFoodCategories = response;
    localGetFoodCategoriesFailed = false;
  }).catch(() => {
  }).finally(() => {
    setFoodCategories(localFoodCategories);
    setGetFoodCategoriesFailed(localGetFoodCategoriesFailed);
    onFoodCategoriesRetrieved(localGetFoodCategoriesFailed, localFoodCategories?.food_categories);
  });
};

Answer 2

useState不会同步更改

useState是同步的吗？

如果要同步使用useState，请使用下面的代码

import { useState, useRef, useEffect } from 'react';

export default function useStateCallback(initialState) {
  const [state, setState] = useState(initialState);
  const cbRef = useRef(null); // mutable ref to store current callback

  // eslint-disable-next-line no-shadow
  const setStateCallback = (state, cb) => {
    cbRef.current = cb; // store passed callback to ref
    setState(state);
  };

  useEffect(() => {
    // cb.current is `null` on initial render, so we only execute cb on state *updates*
    if (cbRef.current) {
      cbRef.current(state);
      cbRef.current = null; // reset callback after execution
    }
  }, [state]);

  return [state, setStateCallback];
}