无法从AsyncStorage获取项目

问题描述

我正在尝试查询我本地保存在设备中的用户数据，并使用它进行API调用。 问题是，当我这样做时，AsyncStorage会在75％的时间内为用户返回null，但是在25％的时间内我可以查询用户，而我不知道问题出在哪里。

const [user,setUser] = useState(null)
  function getQuote() {
    var retrieveData = async () => {
      try {
        const value = await AsyncStorage.getItem("user");
        const data = JSON.parse(value);
        setUser(data.user.email);
      } catch (error) {}
    };
    retrieveData();

    fetch("http://localhost:3000/apI/Order/",{
      method: "POST",body:
        "product_id=" +
        product._id +
        "&user=" +
        user +
        "&quantity=" +
        quote +
        "&status=Request",headers: { "Content-type": "application/x-www-form-urlencoded" },})
      .then((response) => response.json())
      .then((responseJson) => {
        var message = "";
        if (responseJson.result === true) {
          message =
            "Your request for the quote has been made. You will recieve a quote in the quotes tab shortly.";
        } else {
          message =
            "There was an error while send the request. Please try again in a short while.";
        }
        
      });
  }

我也尝试过做

while(user === null){
retrieveData();
}

但这只会使我的应用崩溃。

解决方法

在调用retrieveData函数时，还必须使用异步/等待。 我已经修改了您的代码。现在它可以正常工作了

const [user,setUser] = useState(null)
  async function getQuote() {
    var retrieveData = async () => {
      try {
        const value = await AsyncStorage.getItem("user");
        const data = JSON.parse(value);
        setUser(data.user.email);
      } catch (error) {}
    };
    await retrieveData();

    fetch("http://localhost:3000/api/order/",{
      method: "POST",body:
        "product_id=" +
        product._id +
        "&user=" +
        user +
        "&quantity=" +
        quote +
        "&status=Request",headers: { "Content-type": "application/x-www-form-urlencoded" },})
      .then((response) => response.json())
      .then((responseJson) => {
        var message = "";
        if (responseJson.result === true) {
          message =
            "Your request for the quote has been made. You will recieve a quote in the quotes tab shortly.";
        } else {
          message =
            "There was an error while send the request. Please try again in a short while.";
        }
        
      });
  }