从反应js中的字典中提取数据

Question

我从我的 api 中输出 json 中的数据，并在字典中格式化，我想要一个值，例如每个 frame_number 的 intensity0。我如何在 React JS 中执行此操作我已经尝试了多种方法，但我似乎无法理解。你可以看到我在渲染部分的尝试。

import "bootstrap/dist/css/bootstrap.css";   

import React from "react";    
import Buttons_Footer from "./components/Buttons_Footer.js";
import LeftPane from "./components/LeftPane.js"
//import './App.css';
class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = { apiResponse: "" };

  }
  // Comunicate with API
  callAPI() {
    fetch("http://localhost:9000/IntensityAPI") //React app talks to API at this url
      .then(res => res.text())
      .then(res => this.setState({ apiResponse: res }));
  }
  componentWillMount() {
    this.callAPI();
  }
  render() {
    return (

      <div className="App">
      <ul>
      {this.state.apiResponse.map(function(item,index){
        return (<div><h1>{item.frame_number}</h1></div>)
      })}
      </ul>
        <header className="App-header">
          <p></p>
          <div class="row fixed-bottom no-gutters">
            <div class="col-3 fixed-top fixed-bottom">

              <LeftPane></LeftPane>
            </div>
            <div class="offset-md-3" >

            </div>
          </div>
        </header>
      </div>
    );
  }
}
export default App;

[{"frame_number": 1, "roi0": [101.78202823559488, 99.39509279584912, 49.546951219239915, 29.728170731543948], "intensity0": 80.0, "roi1": [101.78202823559488, 99.39509279584912, 49.546951219239915, 29.728170731543948], "intensity1": 157.0},
{"frame_number": 2, "roi0": [102.56623228630755, 97.95906005049548, 50.25603182631066, 30.153619095786393], "intensity0": 80.0, "roi1": [102.56623228630755, 97.95906005049548, 50.25603182631066, 30.153619095786393], "intensity1": 158.0},
{"frame_number": 3, "roi0": [103.39336535376313, 98.20468223716023, 49.58465295946593, 29.750791775679556], "intensity0": 80.0, "roi1": [103.39336535376313, 98.20468223716023, 49.58465295946593, 29.750791775679556], "intensity1": 157.0}, ... etc

Answer 1

而不是 this.state = { apiResponse: "" }; 使用 this.state = { apiResponse: [] };

将数据解析为 json。而不是 .then(res => res.text()) 使用 .then(res => res.json())

从反应js中的字典中提取数据

Extracting data from a dictionary in react js

api

json

render

reactjs

react-bootstrap