NodeJS 无法读取 JSON 数据中的 [Object]答案

【问题标题】：NodeJS could not read [Object] in JSON dataNodeJS 无法读取 JSON 数据中的 [Object]
【发布时间】：2021-11-23 09:46:24
【问题描述】：

我有 JSON 格式的数据

{"mac":"f008d155b4fe","deviceClass":["iBeacon","eddystone"],"model":"iBeacon","lastSeen":"1637655820","bevent":{"event":"update"},"rssi":{"last":-84},"beacons":[{"ibeacon":{"uuid":"783a69707094d0863b4a9bf94e555241","major":816,"minor":6,"power":0},"eddystone":{"power":0}}],"sensors":{"temperatureC":18,"voltage":3.299999952316284},"stats":{"uptime":"710","adv_cnt":"24","frame_cnt":7}},
        {"mac":"a0e6f8515eff","deviceClass":["arubaTag"],"firmware":{"bankA":"1.2-15"},"assetId":"0000-0000-0000","lastSeen":"1637655821","bevent":{"event":"update"},"rssi":{"last":-69},"sensors":{"battery":83},"stats":{"uptime":"82350","frame_cnt":3},"vendorName":"Aruba"}

我可以从级别 1 打印数据，但我无法从 JSON 打印另一级别的数据我想从信标打印值：[[Object]]，求指点谢谢

这是我的代码

const data = [
        {"mac":"f008d155b4fe","deviceClass":["iBeacon","eddystone"],"model":"iBeacon","lastSeen":"1637655820","bevent":{"event":"update"},"rssi":{"last":-84},"beacons":[{"ibeacon":{"uuid":"783a69707094d0863b4a9bf94e555241","major":816,"minor":6,"power":0},"eddystone":{"power":0}}],"sensors":{"temperatureC":18,"voltage":3.299999952316284},"stats":{"uptime":"710","adv_cnt":"24","frame_cnt":7}},
        {"mac":"a0e6f8515eff","deviceClass":["arubaTag"],"firmware":{"bankA":"1.2-15"},"assetId":"0000-0000-0000","lastSeen":"1637655821","bevent":{"event":"update"},"rssi":{"last":-69},"sensors":{"battery":83},"stats":{"uptime":"82350","frame_cnt":3},"vendorName":"Aruba"}
  ];
  
  const arr1 = data.filter(d => d.mac == "f008d155b4fe");
  console.log('arr1', arr1);
  for (k in arr1.beacons) {
    console.log(k, ":", arr1.beacons[k]);
}

【问题讨论】：

标签： node.js json

【解决方案1】：

这对我有用，我把它全部变成了一个对象，现在你可以通过 newData.devices[0].beacons[0].(property) 访问信标

const newData = {"devices": [{"mac":"f008d155b4fe","deviceClass":["iBeacon","eddystone"],"model":"iBeacon","lastSeen":"1637655820","bevent":{"event":"update"},"rssi":{"last":-84},"beacons":[{"ibeacon":{"uuid":"783a69707094d0863b4a9bf94e555241","major":816,"minor":6,"power":0},"eddystone":{"power":0}}],"sensors":{"temperatureC":18,"voltage":3.299999952316284},"stats":{"uptime":"710","adv_cnt":"24","frame_cnt":7}},         {"mac":"a0e6f8515eff","deviceClass":["arubaTag"],"firmware":{"bankA":"1.2-15"},"assetId":"0000-0000-0000","lastSeen":"1637655821","bevent":{"event":"update"},"rssi":{"last":-69},"sensors":{"battery":83},"stats":{"uptime":"82350","frame_cnt":3},"vendorName":"Aruba"}]};
for (const beacon of newData.devices[0].beacons) {
    console.log(beacon);
}

【讨论】：

【解决方案2】：

您已接近解决方案，但 arr1 是一个数组，因此它没有“信标”属性。请改用以下内容：

    const data = [
        {"mac":"f008d155b4fe","deviceClass":["iBeacon","eddystone"],"model":"iBeacon","lastSeen":"1637655820","bevent":{"event":"update"},"rssi":{"last":-84},"beacons":[{"ibeacon":{"uuid":"7$
        {"mac":"a0e6f8515eff","deviceClass":["arubaTag"],"firmware":{"bankA":"1.2-15"},"assetId":"0000-0000-0000","lastSeen":"1637655821","bevent":{"event":"update"},"rssi":{"last":-69},"sen$
  ];

  const arr1 = data.filter(d => d.mac == "f008d155b4fe");
  console.log('arr1', arr1);
  for (k of arr1) {
    console.log(k.beacons);
}

【讨论】：

【解决方案3】：

arr1 是一个没有 beacons 属性的数组。如果您希望它是 mac 的唯一一项，您应该使用 data.find 而不是 data.filter。也不要使用for-in 循环遍历数组。您可以改用for-of 或.forEach。

const data = [
        {"mac":"f008d155b4fe","deviceClass":["iBeacon","eddystone"],"model":"iBeacon","lastSeen":"1637655820","bevent":{"event":"update"},"rssi":{"last":-84},"beacons":[{"ibeacon":{"uuid":"783a69707094d0863b4a9bf94e555241","major":816,"minor":6,"power":0},"eddystone":{"power":0}}],"sensors":{"temperatureC":18,"voltage":3.299999952316284},"stats":{"uptime":"710","adv_cnt":"24","frame_cnt":7}},
        {"mac":"a0e6f8515eff","deviceClass":["arubaTag"],"firmware":{"bankA":"1.2-15"},"assetId":"0000-0000-0000","lastSeen":"1637655821","bevent":{"event":"update"},"rssi":{"last":-69},"sensors":{"battery":83},"stats":{"uptime":"82350","frame_cnt":3},"vendorName":"Aruba"}
  ];
  
  // expecting only o1 
  const arr1 = data.find(d => d.mac == "f008d155b4fe");
  console.log('arr1', arr1);
  for (const beacon of arr1.beacons) { // use for-of or `forEach`
    console.log(beacon);
}

【讨论】：