Reactjs promise.all

Question

在“获取贷款”之前，我很难让“studentDataPromise”来解决。我需要获取学生的数据，以便能够获取loans....any的想法，我的错误是什么？

目前

1. 调用toggleIsReady()并将其设置为true
2. fetchLoans()被调用，但是由于它依赖于学生数据，所以它不取
3. fetchStudentData()被调用并正确获取
4. fetchClasses()被调用并正确获取

    let studentDataPromise = null;
    let fetchClassesPromise = null;
    let fetchLoansPromise = null;

    useEffect(() => {
        studentDataPromise = fetchStudentData();
    }, []);

    useEffect(() => {
        fetchClassesPromise = fetchClasses();
    }, []);

    useEffect(() => {
        fetchLoansPromise = fetchLoans();
    }, []);

    /**
     * resolves promises and toggles isReady
     * action to true
     */


    Promise.all([studentDataPromise, fetchClassesPromise])
        .then(() => fetchLoansPromise)
        .then(() => toggleIsReady())
        .catch(error => {
            throw new Error(error);
        });

Answer 1

https://stackoverflow.com/a/55502465/11119825

看这个帖子，这是我现在解决的。感谢大家！

Answer 2

如果我理解正确的话，你应该这样做：

    const [student, setStudent] = useState({});
    const [classes, setClasses] = useState([]);
    const [loans, setLoans] = useState([]);
    useEffect(async () => {
        const studentData = await fetchStudentData();
        const fetchClasses = await fetchClasses();
        const fetchLoans = await fetchLoans();
        await toggleIsReady();
    }, []);