在反應中將數據從一個 state 傳遞到另一個 state

Question

const [object, setObject] = useState({
        id: null,
        created_date: "2021-02-18",
        classroom:"",
        name: "",
});

我想將 create_date 值傳遞給另一個 state

const [notify, setNotify] = useState({
        id: 5,
        created_by: "1",
        notification:"object added",
        received_date:created_date,
});

在這里，我想要接收日期中的 created_date 值

Answer 1

您必須為此使用 useEffect ，因為object會隨着時間的推移而發生變異，並且notify必須跟上。

const initialObject = {
        id: null,
        created_date: "2021-02-18",
        classroom:"",
        name: "",
}

const [object, setObject] = useState(initialObject);

const [notify, setNotify] = useState({
        id: 5,
        created_by: "1",
        notification:"object added",
        received_date:initialObject.created_date,
});

useEffect(()=>{
   setNotify(notify => ({...notify, received_date: object.created_date})
}, [object])

Answer 2

這是你想做的參考

import { useState } from "react";

export default function App() {
  const [object, setObject] = useState({
    id: null,
    created_date: "2021-02-18",
    classroom: "",
    name: ""
  });

  const [notify, setNotify] = useState({
    id: 5,
    created_by: "1",
    notification: "object added",
    received_date: object.created_date
  });

  return <div>{notify.received_date}</div>;
}