Question

我想在设置数据时立即响应asyncstorage 但我似乎找不到办法这是我的代码

我的listitem onpress =＆gt; onLearnMore

onLearnMore = (rowData) => {
    this.setState({name:rowData.name}),
    this.setState({email:rowData.email}),
    this.setState({phone:rowData.phone}),
    this.setState({street:rowData.location.street}),
    this.setState({city:rowData.location.city}),
    this.setState({state:rowData.location.state}),
    this.setState({postcode:rowData.location.postcode}),
    this.saveData();
    //this.props.navigation.navigate('Details', { ...rowData });
  };

saveData将项目设置为asyncstorage

saveData(){
    let data = {
      name: this.state.name,
      email: this.state.email,
      phone: this.state.phone,
      street: this.state.street,
      city: this.state.city,
      state: this.state.state,
      postcode: this.state.postcode,
    }
    AsyncStorage.setItem('data',JSON.stringify(data));
    this.previewData();
  }

这是我的previewData

  previewData = async () =>{
    try{
      let datachecker = await AsyncStorage.getItem('data');
      let parsed = JSON.parse(datachecker);
      alert(parsed.name);
    }catch(error){
      alert(error);
    }
  }

但是显示设置为asyncstorage的项目的警报不会立即同步。我需要预览两次以获得与设置状态属性相同的结果

更新错误案例我发现当你设置数据保存到异步存储时它可以立即同步，无论如何都要修复它？

我很抱歉英语不好

Answer 1

setState在您的第一个方法onEarnMore中是异步的，您应该将所有更新批处理到一个setState并将回调传递给第二个参数。

onLearnMore = (rowData) => {
    this.setState({
      name: rowData.name,
      email: rowData.email,
      phone: rowData.phone,
      street: rowData.location.street,
      city: rowData.location.city,
      state: rowData.location.state,
      postcode: rowData.location.postcode
    }, () => {
     // setState second argument is a callback to be invoked
     // after updating state finished
     // this time you can now call any function that depends on the updated state
       this.saveData();
      //this.props.navigation.navigate('Details', { ...rowData })
    });

  };

在你的saveData函数中，AsyncStorage.setItem也是异步的并且返回一个你可以简单地使用.then或await的promise，但如果你使用await，请确保将saveData函数更改为async。

使用.then

AsyncStorage.setItem('data',JSON.stringify(data)).then(this.previewData());

或使用await

async saveData(){
    // omitted code
    await AsyncStorage.setItem('data',JSON.stringify(data));
    this.previewData();
  }

Answer 2

正如名称本身所暗示的那样，它以异步方式存储。为了在完成setItem时执行某些操作，可以传递回调函数。查看http://facebook.github.io/react-native/releases/0.49/docs/asyncstorage.html#setitem

您的代码需要

AsyncStorage.setItem('data',JSON.stringify(data), this.previewData.bind(this));

为什么我的异步存储不会立即同步

2 个答案: