[英]When i use Async/Await i get the warning of : Can't perform a React state update on an unmounted component
[英]I get Error: Can't perform a React state update on an unmounted component even though i created cleanup
一個錯誤一直困擾着我的應用程序說
Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
我確實在我的上下文中聲明了一個 useEffect,以便我可以為我的應用程序存儲和獲取實時數據。
這是我在上下文中的代碼;
const FetchProvider = ({ children }) => {
const [userList, setUserList] = useState([]);
const [teamList, setTeamList] = useState([]);
const authContext = useContext(AuthContext);
const authAxios = axios.create({
baseURL: process.env.REACT_APP_API_URL,
});
useEffect(() => {
let isCancelled = false;
if (
authContext.isAuthenticated &&
authContext.authState.userInfo !== null
) {
const getUsers = async () => {
try {
const users = await authAxios.get('/admin/get-all-users');
if (!isCancelled) {
setUserList(users.data);
}
} catch (error) {
if (!isCancelled) {
console.log(error);
}
}
};
const getTeams = async () => {
try {
const teams = await authAxios.get('/get-all-teams');
if (!isCancelled) {
setTeamList(teams.data);
}
} catch (error) {
if (!isCancelled) {
console.log(error);
}
}
};
getUsers();
getTeams();
}
return () => {
isCancelled = true;
};
}, [authAxios, authContext]);
return (
<Provider
value={{
authAxios,
userList,
setUserList,
teamList,
setTeamList,
}}
>
{children}
</Provider>
);
};
我在我的 Login.jsx 和我的 Login.jsx 中得到了這個錯誤,即使我在提交和聲明它時沒有聲明 useEffect 。
這是我的代碼;
const submitCredentials = async (credentials, resetForm) => {
try {
setLoginLoading(true);
const { data } = await publicFetch.post('signin', credentials);
authContext.setAuthState(data);
setSignupSuccess(data.message);
setSignupError('');
setOpen(true);
setTimeout(() => {
setLoginLoading(false);
setredirectOnlogin(true);
resetForm(true);
}, 400);
} catch (error) {
setLoginLoading(false);
const { data } = error.response;
setSignupError(data.message);
setSignupSuccess('');
setOpen(true);
}
return setLoginLoading(false);
};
我已經嘗試了互聯網提供的許多方法來解決這個問題,但不幸的是它並沒有解決我的問題。
我的 UsersTable.jsx 和 TeamTables.jsx 中確實有 useEffect。
這是我在 UsersTable.jsx 中的代碼;
useEffect(() => {
let isCancelled = false;
const getUsers = async () => {
try {
const users = await fetchContext.authAxios.get('/admin/get-all-users');
setIsLoaded(true);
if (isLoaded === true) {
if (!isCancelled) {
fetchContext.setUserList(users.data);
}
}
return () => {
isCancelled = true;
};
} catch (error) {
if (!isCancelled) {
console.log(error);
}
}
};
getUsers();
return () => {
isCancelled = true;
};
}, [fetchContext, isLoaded]);
這是我的 TeamTable.jsx 中的 useEffect 代碼;
useEffect(() => {
let isCancelled = false;
const getTeams = async () => {
try {
const teams = await fetchContext.authAxios.get('get-all-teams');
setIsLoaded(true);
if (isLoaded === true) {
if (!isCancelled) {
fetchContext.setTeamList(teams.data);
}
}
} catch (error) {
if (!isCancelled) {
console.log(error);
}
}
};
getTeams();
return () => {
isCancelled = true;
};
}, [fetchContext, isLoaded]);
isLoaded 用作 AJAX
好吧,你可以使用 React 推薦的方法來解決這個問題。 您需要做的就是將 api 調用包裝在 makeCancellable 方法中,並在卸載組件時取消它們。
參考: https://reactjs.org/blog/2015/12/16/ismounted-antipattern.html
為此創建
const makeCancelable = (promise) => {
let isCancelled = false;
const wrappedPromise = new Promise((resolve, reject) => {
promise.then(
val => isCancelled ? reject({isCanceled: true}) : resolve(val),
error => isCancelled ? reject({isCanceled: true}) : reject(error)
);
});
return {
promise: wrappedPromise,
cancel() {
isCancelled = true;
},
};
};
為您的useEffect
之外的請求創建一個變量
let fetchTeamsRequest = null;
並更新了您的useEffect
function,如下所示。
useEffect(() => {
const getTeams = async () => {
if (fetchTeamsRequest) {
try {
await fetchTeamsRequest.promise;
return;
} catch (error) {
return;
}
}
fetchTeamsRequest = makeCancellable(fetchContext.authAxios.get('get-all-teams'));
try {
const teams = await fetchTeamsRequest.promise;
fetchTeamsRequest = null;
setIsLoaded(true);
if (isLoaded === true) {
if (!fetchTeamsRequest.isCancelled) {
fetchContext.setTeamList(teams.data);
}
}
} catch (error) {
if (!fetchTeamsRequest.isCancelled) {
fetchTeamsRequest = null;
console.log(error);
}
}
};
getTeams();
return () => {
if (fetchTeamsRequest) {
fetchTeamsRequest.cancel();
}
};
}, [fetchContext, isLoaded]);
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