在 React JS 中解析 JSON 值并映射到组件

Question

我已经被困了好几天试图从 Fetch API JSON 结果中将数据提取到我的组件中。作为一个 React 初学者，这对我来说是一个挑战，任何帮助我学习和解决问题的方向都是值得赞赏的。我在下面复制了以下 JSON 响应，然后是我的组件设置。

我的想法是，我没有按顺序提取正确的 JSON 键值或类似的内容。

JSON：

{
  "data": [
    {
      "virusIndex": 2,
      "temperature": 26.5,
      "humidity": 58.6,
      "pm25": 3,
      "tvoc": 234,
      "co2": 435,
      "co": 0,
      "airPressure": 991,
      "ozone": 8.7,
      "no2": 19.4,
      "timestamp": 1646109873
    }
  ],
  "usersettings": {
    "temperature": "°C",
    "temp": "c",
    "humidity": "%",
    "pm25": "µg/m^3",
    "dust": "µg/m^3",
    "tvoc": "ppb",
    "voc": "ppb",
    "co2": "ppm",
    "co": "ppm",
    "airPressure": "mbar",
    "pressure": "mbar",
    "ozone": "ppb",
    "no2": "ppb",
    "pm1": "µg/m^3",
    "pm4": "µg/m^3",
    "pm10": "µg/m^3",
    "ch2o": "ppb",
    "light": "lux",
    "sound": "dBA"
  },
  "count": 104
}

应用程序.js：

class App extends Component {

  constructor(props) {
    super(props);
    this.state = {
      airData: []
    }
   }

componentDidMount(){
var myHeaders = new Headers();
      myHeaders.append("Authorization", "Bearer xxxxxxxxx");

      var urlencoded = new URLSearchParams();
      urlencoded.append("macAddress", "xxxxxxxx");
      urlencoded.append("mode", "minute");

      var requestOptions = {
      method: 'POST',
      headers: myHeaders,
      body: urlencoded,
      redirect: 'follow'
      };

  fetch("MY_API_URL", requestOptions)
   .then(response => response.json())
   .then(res => {
     console.log(res)
     this.setState({
       airData: res.data
     })
   });
  }


  
  render () {
        return (
          <div className="app">
            <Header />
            <div className="spacer"></div>
            <OverallStatus />
            {this.state.airData.map(res => {
                  <div>
                    <div className='qualityFactor'>
                      <h1><img src={iconHumidity} alt="Logo" className="iconSmall" />Humidity {res.humidity}%</h1>
                      <ProgressBar completed={res.humidity}
                      maxCompleted={100} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconAirPressure} alt="Logo" className="iconSmall" />Air Pressure {e.AirPressure} hPa</h1>
                      <ProgressBar completed={e.AirPressure}
                      maxCompleted={1030} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconCarbonDioxide} alt="Logo" className="iconSmall" />Carbon Dioxide {e.CO2} ppm</h1>
                      <ProgressBar completed={e.CO2}
                      maxCompleted={2000} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconVOCs} alt="Logo" className="iconSmall" />Chemicals {e.TVOC} ppb</h1>
                      <ProgressBar completed={e.TVOC}
                      maxCompleted={1000} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconParticulateMatter} alt="Logo" className="iconSmall" />Particles {e.PM25} ug/m3</h1>
                      <ProgressBar completed={e.PM25}
                      maxCompleted={100} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconCarbonMonoxide} alt="Logo" className="iconSmall" />Carbon Monoxide {e.CO} ppm</h1>
                      <ProgressBar completed={e.CO}
                      maxCompleted={100} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconNitrogenDioxide} alt="Logo" className="iconSmall" />Nitrogen Dioxide {e.NO2} ppb</h1>
                      <ProgressBar completed={e.NO2}
                      maxCompleted={200} className="statusBar" />
                    </div>
                    <div className='qualityFactor'>
                      <h1><img src={iconOzone} alt="Logo" className="iconSmall" />Ozone {e.Ozone} ppb</h1>
                      <ProgressBar completed={e.Ozone}
                      maxCompleted={100} className="statusBar" />
                    </div>
                  </div>
              })}
          </div>
        )
    }
  }
  
  

export default App;

Answer 1

Javascript 对象键区分大小写。因此，e.CO2 与 e.co2 不同。

另外，您还没有声明变量“e”，但您正在使用它。它应该是“res”

您还错过了地图函数内的return语句。