Question

我正在尝试从http调用解析json。为此，我写了http调用，我得到了像this

这样的数据

[ //list of streams
  {
    "entry": "stream",
    "value": {
      "name": "euro", //stream name
      "urls": [ //list of sources
        {
          "value": "tshttp://192.168.1.2:6502", //source URL
          "options": [ //source switching options
            [
              "priority",
              "1"
            ],
            [
              "source_timeout",
              "30"
            ]
          ]
        }
      ],
      "stats": {
        "alive": true, //true if there are recent frames in the stream
        "bitrate": 3690, //biteate
        "bufferings": 0,
        "client_count": 0, //number of clients (viewers) of this stream
        "dash": true, //DASH enabled
        "dvr_enabled": false, //archive recording disabled
        "hds": true, //HDS enabled
        "hls": true, //HLS enabled
        "input_error_rate": 0, //number of errors registered per second
        "last_access_at": 1493279230436,
        "media_info": { //stream content info
          "height": 576, //image height
          "streams": [
            {
              "bitrate": 191, //biteate
              "codec": "mp2a", //codec
              "content": "audio", //content type:audio
              "lang": "eng", //language
              "track_id": "a1" //track number
            },
            {
              "bitrate": 3256, //bitrate
              "codec": "mp2v", //codec
              "content": "video", //content type: video
              "size": "1024x576", //image size
              "track_id": "v1" //track number
            }
          ],
          "width": 1024 //image width
        },
        "out_bandwidth": 4002, //out bandwidth
        "push_stats": { //stream copy statistisc, bytes
          "tshttp://container4:8080/static1/mpegts": 2000918592
        },
        "remote": false, //the stream is not repeated from another Flussonic
        "retry_count": 0, //number of automatic retries
        "running": true, //stream is being broadcased, does not necessarily mean there are frames in the stream
        "start_running_at": 1493279194382,
        "ts_delay": 113, //milliseconds since the most recent frame in the stream 
        "url": "tshttp://192.168.1.2:6502" //URL of current source
      },
      "options": { //stream configuration
        "static": false, 
        "retry_limit": 10,
        "clients_timeout": 60,
        "source_timeout": 60,
        "pushes": [ 
          [
            "tshttp://container4:8080/static1/mpegts"
          ]
        ],
        "publish_enabled": false,
        "add_audio_only": false,
        "dash_off": false,
        "dvr_protected": false,
        "hds_off": false,
        "hls_off": false,
        "m4s_off": false,
        "mpegts_off": false,
        "pulse_off": false,
        "rtmp_off": false,
        "rtsp_off": false,
        "webrtc_off": false
      }
    }
  },
  ...
]

因此，如果我想获得视频比特率，我必须写下这个：

video_bitrate: data.value.stats.media_info.streams[1].bitrate

但有时比特率值不存在并抛出异常。我不想那样，我怎么检查呢？

我找到的一种方式是我必须写：

if(data.hasOwnProperty('value')) {
 if (data.value.hasOwnProperty('value')) {
  ...
  if(data.value.stats.media_info.streams[1].hasOwnerProperty('bitrate') {...}
 }
}

但它太长而且丑陋。我还能做什么？

Answer 1

您可以使用jsonpath：

var jp = require('jsonpath');
var bitrates = jp.query(data, '$..streams[1].bitrate');

Answer 2

尝试javascript的三元运算符：D https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator

const has_it = data.hasOwnProperty('value') ? true : false;

通过验证解析json

2 个答案: