无法在 useEffect 内部设置 state

Question

I'd like to set a value to nickid state using react hooks.

UID from database has a value, then I set the state and console.log after it, it shows null.

any ideas why?

My code:

const [nickid, setNickid] = useState(null); //uid

useEffect(() => {
    firebase.database().ref('/users/').orderByChild('user').equalTo(props.match.params.user).once('value').then(snapshot => {
        if (snapshot.exists()){
            var uid = Object.keys(snapshot.val())[0]; //uid has a value
            setNickid({ nickid: uid });

            console.log(nickid); // here is null

Answer 1

First thing setState/setNickid is async function so you will not get direct that value right after it

Second , change this

setNickid({ nickid: uid });

To

setNickid(uid);

WORKING DEMO

Answer 2

setState is async function (does not execute immediately) if you want to console log nickid when it is changed

useEffect(()=>{
  console.log(nickid)
},[nickid])