fetchById无法在react中呈现状态，但console.log正确呈现状态

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

function MyComponent() {
  const [data, setData] = useState(null);

  useEffect(() => {
    const fetchData = async () => {
      const result = await fetchById();
      setData(result);
    };

    fetchData();
  }, []); // 空依赖数组确保只在组件挂载时执行一次

  useEffect(() => {
    console.log('Data updated:', data);
  }, [data]); // 监听 data 的变化并打印

  return (
    <div>
      {data ? <p>{data}</p> : <p>Loading...</p>}
    </div>
  );
}

const fetchData = async () => {
  const result = await fetchById();
  setData(prevData => ({ ...prevData, ...result }));
};

const fetchData = async () => {
  try {
    const result = await fetchById();
    if (result) {
      setData(result);
    } else {
      setData(null); // 或者设置一个默认值
    }
  } catch (error) {
    console.error('Error fetching data:', error);
    setData(null); // 处理错误情况
  }
};