gpx文件扩展节点gpxtpx:TrackPointExtension

Question

我正在尝试读取在Garmin GPS设备中创建的GPX文件。我有以下代码来尝试提取所有数据，但它挂在节点及其子节点中，即=>

这是代码

//returns http://www.topografix.com/GPX/1/1
XNamespace gpx = GetGpxNameSpace();
XDocument gpxDoc = GetGpxDoc();
XNamespace gpxtpx = XNamespace.Get("gpxtpx");
var waypoints = from waypoint in gpxDoc.Descendants(gpx + "trkpt")
                select new
                {
                    Latitude = waypoint.Attribute("lat").Value,
                    Longitude = waypoint.Attribute("lon").Value,
                    Elevation = waypoint.Element(gpx + "ele") != null ?
                        waypoint.Element(gpx + "ele").Value : null,
                    Dt = waypoint.Element(gpx + "time") != null ?
                        waypoint.Element(gpx + "time").Value : null,
                    hr = waypoint.Element(gpx+ "extensions").Element(gpxtpx +"TrackPointExtension").Element(gpxtpx +"hr").Value
                };
StringBuilder sb = new StringBuilder();
foreach (var wpt in waypoints)
{
    // This is where we'd instantiate data
    // containers for the information retrieved.
    sb.Append(
        string.Format("Name:{0} Latitude:{1} Longitude:{2} Elevation:{3} Date:{4}n",
        "x", wpt.Latitude, wpt.Longitude,
        wpt.Elevation, wpt.Dt));
}
return sb.ToString();

和xml节点

<trkseg>
   <trkpt lon="-111.5252978168428" lat="35.07395471446216">
      <ele>2084.800048828125</ele>
      <time>2012-07-15T14:47:16.000Z</time>
      <extensions>
         <gpxtpx:TrackPointExtension>
            <gpxtpx:hr>155</gpxtpx:hr>
         </gpxtpx:TrackPointExtension>
      </extensions>
   </trkpt>
...
</trkseg>

我可以访问所有其他节点，但当尝试访问hr节点时，我会出错。

感谢您的帮助。

Answer 1

尝试更改

XNamespace gpxtpx = XNamespace.Get("gpxtpx");

至

XNamespace gpxtpx = XNamespace.Get("http://www.garmin.com/xmlschemas/TrackPointExtension/v1");

Answer 2

上面的名称空间建议有效，我发现有必要防止空节点：

HeartRate = trackpoint.Element(gpx + "extensions") != null ?
                                      (trackpoint.Element(gpx + "extensions").Element(gpxtpx + "TrackPointExtension") != null ?
                                       (trackpoint.Element(gpx + "extensions").Element(gpxtpx + "TrackPointExtension").Element(gpxtpx +"hr") != null ? 
                                          trackpoint.Element(gpx + "extensions").Element(gpxtpx + "TrackPointExtension").Element(gpxtpx +"hr").Value : null ) : null   ) : null