用例
我试图从我的箭头函数中获取数据,并在单击按钮时以表格格式显示。
这是我的反应组件
import React, { Component } from "react";
export default class DisplayStats extends Component {
handleClick = () => {
var params = {
EndTime: 1536172199,
MetricDataQueries: [
{
Id: 'm17',
MetricStat: {
Metric: {
Dimensions: [
{
Name: 'BucketName',
Value: BName
},
],
MetricName: 'BucketSizeBytes',
Namespace: 'AWS/S3'
},
Period: 86400,
Stat: 'Sum',
Unit: 'Bytes'
},
ReturnData: true
},
{
Id: 'm18',
MetricStat: {
Metric: {
Dimensions: [
{
Name: 'BucketName',
Value: BName
},
],
MetricName: 'BucketSizeBytes',
Namespace: 'AWS/S3'
},
Period: 86400,
Stat: 'Sum',
Unit: 'Bytes'
},
ReturnData: true
},
],
};
cloudwatch.getMetricData(params, function(err, data) {
if (err) {
console.log(err, err.stack);
}
else
{
const a = JSON.stringify(data);
}
});
}
render() {
return (
<div className="container">
<h1>This is the stats.</h1>
<button onClick={this.handleClick}>Click Me</button>
</div>
)
}
}
因此,当我点击按钮时,它将触发箭头功能并给出响应。控制台中的响应看起来像这样
{"ResponseMetadata":{"RequestId":"12345"},"MetricDataResults":[{"Id":"m17","Label":"StandardStorage BucketSizeBytes","Timestamps":["2018-09-04T18:30:00.000Z"],"Values":[38497162],"StatusCode":"Complete","Messages":[]},{"Id":"m18","Label":"AllStorageTypes NumberOfObjects","Timestamps":["2018-09-04T18:30:00.000Z"],"Values":[10],"StatusCode":"Complete","Messages":[]}]}
为此我已经返回map函数来从上面的json中检索元素。地图功能就是这样的
var names = obj.MetricDataResults.map(function (MetricDataResults) {
return MetricDataResults.Id + ' ' + MetricDataResults.Label + ' ' + MetricDataResults.Timestamps + ' ' + MetricDataResults.Values + ' ' + MetricDataResults.StatusCode + ' ' + MetricDataResults.Messages;
});
假设一切都存储在变量obj
中。
现在我对两件事情感到震惊:
render()
方法中使用它。谢谢任何帮助表示赞赏。
您应该将数据保存在您的状态,然后将其呈现到DOM中。
const data = {
ResponseMetadata: { RequestId: "12345" },
MetricDataResults: [
{
Id: "m17",
Label: "StandardStorage BucketSizeBytes",
Timestamps: ["2018-09-04T18:30:00.000Z"],
Values: [38497162],
StatusCode: "Complete",
Messages: []
},
{
Id: "m18",
Label: "AllStorageTypes NumberOfObjects",
Timestamps: ["2018-09-04T18:30:00.000Z"],
Values: [10],
StatusCode: "Complete",
Messages: []
}
]
};
const fakeRequest = () =>
new Promise(resolve => setTimeout(() => resolve(data)));
class App extends React.Component {
state = {
data: {}
};
handleClick = () => fakeRequest().then(data=> this.setState({ data }));
renderResults = () =>
this.state.data.MetricDataResults.map(MetricDataResults => (
<div key={MetricDataResults.Id}>
<p>ID: {MetricDataResults.Id}</p>
<p>Label: {MetricDataResults.Label}</p>
<p>Timestamp: {MetricDataResults.Timestamps}</p>
<p>Values: {MetricDataResults.Values}</p>
<p>StatusCode: {MetricDataResults.StatusCode}</p>
<p>Messages: {MetricDataResults.Messages}</p>
</div>
));
render() {
return (
<div>
{this.state.data.MetricDataResults &&
this.renderResults()}
<button onClick={this.handleClick}>Get results</button>
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById("root"));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="root"></div>
根据您的情况设置您的州将是这样的:
cloudwatch.getMetricData(params, (err, data) => {
if (err) {
// if you want to keep error in the state
this.setState({ error: error.stack });
} else {
// data should be in your state as data: {}
this.setState({ data });
}
});
应该是这样的:
render() {
return obj.MetricDataResults.map((MetricDataResults) => {
return (
<div>
{MetricDataResults.Id + ' ' + MetricDataResults.Label + ' ' + MetricDataResults.Timestamps + ' ' + MetricDataResults.Values + ' ' + MetricDataResults.StatusCode + ' ' + MetricDataResults.Messages}
</div>
);
});
}
render() {
return obj.MetricDataResults.map(item => (
<div>
{`${item.Id} ${item.Label} ${item.Timestamps} ${item.Values} ${item.StatusCode} ${item.Messages}`}
</div>
);
});
}