如何获取 function 中传递给另一个组件的 useState 变量的值

Question

The best way to describe question is my code:

function EstateParamsList({ estateType, category }) {
  const [isLoading, setIsLoading] = useState(true)
  const [params, setParams] = useState({})
  const [showPopUp, setShowPopUp] = useState(false)

  useEffect(() => {
    if (category && typeof category.id !== undefined) {
      return db.collection(`dictionaries/ESTATE_PARAMS/${estateType}/${category.id}/params`).onSnapshot(response => {
        const paramsObject = {}
        response.forEach(param => {
          paramsObject[param.id] = {
            ...convertParamObjetcToFieldsConfig(param.data()),
            change: fieldChangedHandler
          }
        })
        setParams(paramsObject)
        setIsLoading(false)
      })
    } else {
      setIsLoading(false)
    }
  }, [category])
 console.log(params)
  const fieldChangedHandler = (event, fieldIdentifier) => {
    if(params)
      console.log(params)
  }

So i have params variable, that im init with object, that i'm getting async from firebase. Implementation of initializing you can see in useEffect method . For every object i want to pass ref for the function "fieldChangedHandler", for managing value of inputs.

fieldChangedHandler is a method of my EstateParamsList . But there i cant get value of params!

Question is WHY? I'm calling fieldChangedHandler only after everything was rendered, and async request was done.

Below is console log of params. Why in func is empty params ?

Calling:

const renderParamsAsFields = params => {
  const fields = []
  for (const key in params) {
    fields.push(<Field {...params[key]} changed={event => params[key].change(event, key)} />)
  }
  return fields.length ? fields : <div className='EstateParamsManager-EmptyValues'>Нет параметров</div>
}

Answer 1

Why not use curried function?

const createFieldChangedHandler = (
  params,
  fieldIdentifier
) => event => {
  if (params) console.log(params);
};

function EstateParamsList({ estateType, category }) {
//... other code
  useEffect(() => {
    //...other code
    change: createFieldChangedHandler(
       paramsObject,
       param.id
    ),
    //...other code
   }, [category, estateType]);//fixed missing dependency

When you call the change function you should already have the right values in scope:

<Field {...params[key]} changed={params[key].change} />