Question

我的函数生成一个随机数，并检查它是否已经存在于数据库中。问题是我在注册新用户时使用了此函数，并且需要在此处添加一个Promise，以便该函数不会返回null。

有人可以告诉我我该怎么写，以便可以确定首先返回import * as React from 'react'; import { Text, View, StyleSheet,Button } from 'react-native'; import RadioForm, { RadioButton, RadioButtonInput, RadioButtonLabel } from 'react-native-simple-radio-button'; export default class App extends React.Component { state = { ages: [ {key:1,label:20}, {key:2,label:30}, {key:3,label:40}, ], initialRadioPos: -1 } render() { return ( <View style={styles.container}> <View style={{ flexDirection: 'column', marginTop: 10, alignItems: 'flex-start', }}> <RadioForm radio_props={this.state.ages} initial={this.state.initialRadioPos} formHorizontal={false} labelHorizontal={true} buttonColor={this.state.switched ? '#673AB7' : '#A9A9A9'} selectedButtonColor={this.state.switched ? '#673AB7' : '#A9A9A9'} onPress={currentAge => { this.setState({ currentAge }); }} /> <Button title="submit" onPress={()=>this.clear()}/> </View> </View> ); } clear = () =>{ this.setState({ initialRadioPos:-1 }) } } const styles = StyleSheet.create({ container: { flex: 1, justifyContent: 'center', backgroundColor: '#ecf0f1', padding: 8, }, });。

getAccountBill()

我的注册控制器：

  function getAccountBill() {
    const accountBill = `2222${Math.floor(
      Math.random() * 90000000000000000000,
    ) + 10000000000000000000}`;

    Bill.findOne({
      where: {
        account_bill: accountBill,
      },
    })
      .then(isAccountBill => {
        if (isAccountBill) {
          getAccountBill();
        }
        console.log('accountBill', accountBill);
        return accountBill;
      })
      .catch(err => {
        /* just ignore */
      });
  }

Answer 1

鉴于getAccountBill内部对Mongo进行了异步调用，您可以返回其结果并await对其进行调用，然后再调用Bill.create。

async / await使以同步方式编写异步代码变得非常容易。

async function getAccountBill() {
  const accountBill = `2222${Math.floor(
    Math.random() * 90000000000000000000,
  ) + 10000000000000000000}`;

  try {
    const acct = await Bill.findOne({
      where: {
        account_bill: accountBill,
      },
    });
    return acct ? await getAccountBill() : accountBill;
  } catch(e) {
    // if you ignore the error, at least log it
    console.error(e);
  }
}

然后在控制器中，等待帐号，然后再创建帐户

const user = await User.create({
  login: req.body.login,
  password: req.body.password,
  name: req.body.name,
  surname: req.body.surname,
  email: req.body.email,
  date_registration: getTodayDate(),
});
const account_bill = await getAccountBill();
const bill = await Bill.create({
  id_owner: user.id,
  account_bill,
  available_funds: getAvailableFunds(),
})
const additional = await Additional.create({
  id_owner: user.id,
  account_balance_history: getAccountBalanceHistory(),
});
res.status(200).json({ register: true });

生成随机数并检查数据库JavaScript NodeJS中是否存在该随机数

1 个答案: