Reactjs 在React中设置异步/等待状态
在代码示例中,我试图使用Reactjs 在React中设置异步/等待状态,reactjs,promise,async-await,react-native,es6-promise,Reactjs,Promise,Async Await,React Native,Es6 Promise,在代码示例中,我试图使用Promise对象数组调用setState()。数据(坐标)必须从外部REST服务获取 在React中执行此操作是否有共同的模式 async getLocations(locations) { var annotations = locations.map(this.getLocation); console.log("ANNOTATIONS:", annotations); this.setState({ annotat
Promise
对象数组调用setState()
。数据(坐标)必须从外部REST服务获取
在React中执行此操作是否有共同的模式
async getLocations(locations) {
var annotations = locations.map(this.getLocation);
console.log("ANNOTATIONS:", annotations);
this.setState({
annotations:annotations
});
}
async getLocation(location) {
try {
let res = await Geocoder.geocodeAddress(location.address);
return (
{
latitude: res[0].position.lat,
longitude: res[0].position.lng,
title: location.address,
subtitle: location.provider,
}
);
}
catch(err) {
console.log("Error fetching geodata",err);
}
return null;
}
结果数组包含Promise对象,状态更新结果出错:
ANNOTATIONS: [Promise, Promise, Promise, Promise, Promise, Promise, Promise]
ExceptionsManager.js:70 Warning: Failed prop type: Required prop `annotations[0].latitude` was not specified in `MapView`.
in MapView (at index.js:204)
in SampleAppInspection (at renderApplication.ios.js:90)
in RCTView (at View.js:348)
in View (at renderApplication.ios.js:65)
in RCTView (at View.js:348)
in View (at renderApplication.ios.js:64)
in AppContainer (at renderApplication.ios.js:89)
这其实很简单。您需要打开正在传递的承诺数组
setState
,因为它不支持承诺:
this.setState({
annotations: await Promise.all(annotations)
});
Promise.all
部分等待整个数组,而wait则将其展开,以便setState
查看