我得到错误：即使我创建了清理，也无法对未安装的组件执行 React state 更新

Question

An error keeps bothering me on my app says

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.

I do declare a useEffect in my Context so that I can have a realtime data storing and getting for my app.

Here is my code in Context;

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>
    );
};

And I get this error in my Login.jsx and in my even though I don't declare useEffect in submitting and declaring it in.

Here is my code;

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);
    };

And I have tried many ways the internet has offered to fix this up but unfortunately it does not fix my problem.

I do have useEffect in my UsersTable.jsx and TeamTables.jsx.

Here is my code in UsersTable.jsx;

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]);

Here is my useEffect code in my TeamTable.jsx;

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]);

The isLoaded is used as an AJAX

Answer 1

Well, you can use the React recommended way to fix this issue. All you need to do is wrap your api call within makeCancellable method and cancel them when your component is unmounting.

Ref: https://reactjs.org/blog/2015/12/16/ismounted-antipattern.html

To do that create

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;
    },
  };
};

create a variable for the request outside your useEffect

let fetchTeamsRequest = null;

and updated your useEffect function like below.

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]);