Reactjs 为什么“useState（）”似乎不起作用？

我有一些需要动态生成的对象属性。该对象是Formik组件的initialValues对象

当我尝试在useEffect调用中更新FormValue时，它们似乎不起作用

useEffect(() => {
    async function getRoles() {
      let res

      try {
        res = await fetch(`http://localhost/roles?active=Yes`)
      } catch (err) {
        console.log('Err in getRoles', JSON.stringify(err))
      }
      const { rows } = await res.json()

      console.log('rows: ' + JSON.stringify(rows))
      setRoles(rows)

      const possibleRoles = {}
      rows.forEach((role, index) => {
        const key = role.code.toLowerCase()
        possibleRoles[key + '_reviewer'] = ''
      })

      console.log('formValues before: ' + JSON.stringify(formValues))
      console.log('possibleRoles: ' + JSON.stringify(possibleRoles))

      const newValues = { ...possibleRoles, ...formValues }
      console.log('newValues: ' + JSON.stringify(newValues))

      setFormValues({ ...newValues })
      console.log('formValues after: ' + JSON.stringify(formValues))

    }

    getRoles()

    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []
)

// console results:
rows: [{"code":"aaa"},{"code":"bbb"},{"code":"ccc"}]
formValues before: {"formChoice":"","sectionChoices":[],"requestor":"dd","materials":""}
possibleRoles: {"aaa_reviewer":"","bbb_reviewer":"","ccc_reviewer":""}
newValues: {"aaa_reviewer":"","bbb_reviewer":"","ccc_reviewer":"","formChoice":"","sectionChoices":[],"requestor":"dd","materials":""}
formValues after: {"formChoice":"","sectionChoices":[],"requestor":"dd","materials":""}

我做错了什么？这是我的解构吗？

尝试使用useEffect之类的东西

这将在初始渲染时进行

const [roles, setRoles] = useState([]);

 useEffect(() => {
   async function getRoles() {
      let res

      try {
        res = await fetch(`http://localhost/roles?active=Yes`)
      } catch (err) {
        console.log('Err in getRoles', JSON.stringify(err))
      }
      const { rows } = await res.json()

      console.log('rows: ' + JSON.stringify(rows))
      setRoles(rows)
     }
  }, []);

现在只需观察另一个useEffect块中状态角色的变化

---

如果您的Formik状态已更新但未出现在浏览器中，请尝试启用Formik表单上的重新初始化道具。您会看到以前的状态，因为setState是异步的。当你想在useEffect中使用道具时，你必须设置依赖项，这样你就应该在[]中放入initialValues。如果我在[]中放入initialValues，我会得到一个可爱的无限循环。我曾假设setState上的等待将避免异步性质。尝试过同样的结果+无限循环，因为它会重新呈现Formik

useEffect(() => {
    const possibleRoles = {}
      roles.forEach((role, index) => {
        const key = role.code.toLowerCase()
        possibleRoles[key + '_reviewer'] = ''
      })


      console.log('formValues before: ' + JSON.stringify(formValues))
      console.log('possibleRoles: ' + JSON.stringify(possibleRoles))

      const newValues = { ...possibleRoles, ...formValues }
      console.log('newValues: ' + JSON.stringify(newValues))

      setFormValues({ ...newValues })
      console.log('formValues after: ' + JSON.stringify(formValues))

  }, [roles]);