解析XML命名空间节点

huangapple
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英文:

Parsing XML namespaced nodes

问题

我对Go相对较新，但在一个基本任务上遇到了困难。我正在使用"encoding/xml"包解析一个GPX文件，并有以下示例xml数据;

  1. <gpx creator="StravaGPX" version="1.1" xmlns="http://www.topografix.com/GPX/1/1" 
  3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd" xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1" xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3">
  4.  <metadata>
  5.   <time>2013-02-16T10:11:25Z</time>
  6.  </metadata>
  7.  <trk>
  8.   <name>Demo Data</name>
  9.   <trkseg>
  10.    <trkpt lat="51.6395658" lon="-3.3623858">
  11.     <ele>111.6</ele>
  12.     <time>2013-02-16T10:11:25Z</time>
  13.     <extensions>
  14.      <gpxtpx:TrackPointExtension>
  15.       <gpxtpx:atemp>8</gpxtpx:atemp>
  16.       <gpxtpx:hr>136</gpxtpx:hr>
  17.       <gpxtpx:cad>0</gpxtpx:cad>
  18.      </gpxtpx:TrackPointExtension>
  19.     </extensions>
  20.    </trkpt>

到目前为止，我能够使用以下类型获取最基本的信息;

  1. type Gpx struct {
  2. 	Creator string `xml:"creator,attr"`
  3. 	Time string `xml:"metadata>time"`
  4. 	Title string `xml:"trk>name"`
  5. 	TrackPoints []TrackPoint `xml:"trk>trkseg>trkpt"`
  6. }
  8. type TrackPoint struct {
  9. 	Lat float64 `xml:"lat,attr"`
  10. 	Lon float64 `xml:"lon,attr"`
  11. 	Elevation float32 `xml:"ele"`
  12. 	Time string `xml:"time"`
  13. 	Temperature int `xml:"extensions>gpxtpx>atemp"`
  14. }

我在TrackPoint.Temperature的解析中失败了。我无法正确匹配扩展节点下的命名空间节点。

有关我出错的地方有什么建议吗？

英文:

I am relatively new to Go but struggling with a basic task. I am parsing a GPX file using the "encoding/xml" package and have the following example xml data;

  1. &lt;gpx creator=&quot;StravaGPX&quot; version=&quot;1.1&quot; xmlns=&quot;http://www.topografix.com/GPX/1/1&quot; 
  3. xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot; xsi:schemaLocation=&quot;http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd&quot; xmlns:gpxtpx=&quot;http://www.garmin.com/xmlschemas/TrackPointExtension/v1&quot; xmlns:gpxx=&quot;http://www.garmin.com/xmlschemas/GpxExtensions/v3&quot;&gt;
  4.  &lt;metadata&gt;
  5.   &lt;time&gt;2013-02-16T10:11:25Z&lt;/time&gt;
  6.  &lt;/metadata&gt;
  7.  &lt;trk&gt;
  8.   &lt;name&gt;Demo Data&lt;/name&gt;
  9.   &lt;trkseg&gt;
  10.    &lt;trkpt lat=&quot;51.6395658&quot; lon=&quot;-3.3623858&quot;&gt;
  11.     &lt;ele&gt;111.6&lt;/ele&gt;
  12.     &lt;time&gt;2013-02-16T10:11:25Z&lt;/time&gt;
  13.     &lt;extensions&gt;
  14.      &lt;gpxtpx:TrackPointExtension&gt;
  15.       &lt;gpxtpx:atemp&gt;8&lt;/gpxtpx:atemp&gt;
  16.       &lt;gpxtpx:hr&gt;136&lt;/gpxtpx:hr&gt;
  17.       &lt;gpxtpx:cad&gt;0&lt;/gpxtpx:cad&gt;
  18.      &lt;/gpxtpx:TrackPointExtension&gt;
  19.     &lt;/extensions&gt;
  20.    &lt;/trkpt&gt;

So far I am able to get at the most basic info with the following types;

  1. type Gpx struct {
  2. 	Creator string `xml:&quot;creator,attr&quot;`
  3. 	Time string `xml:&quot;metadata&gt;time&quot;`
  4. 	Title string `xml:&quot;trk&gt;name&quot;`
  5. 	TrackPoints []TrackPoint `xml:&quot;trk&gt;trkseg&gt;trkpt&quot;`
  6. }
  8. type TrackPoint struct {
  9. 	Lat float64 `xml:&quot;lat,attr&quot;`
  10. 	Lon float64 `xml:&quot;lon,attr&quot;`
  11. 	Elevation float32 `xml:&quot;ele&quot;`
  12. 	Time string `xml:&quot;time&quot;`
  13. 	Temperature int `xml:&quot;extensions&gt;gpxtpx&gt;atemp&quot;`
  14. }

Where I am failing to parse is in TrackPoint.Temperature. I cannot get the tag right to match the namespaced nodes underneath extensions.

Any suggestions as to where I am going wrong?

答案1

得分: 1

你的TrackPoint.Temperature xml指令中，你正在针对一个命名空间而不是一个变量名进行定位。

将

  1. Temperature int `xml:"extensions>gpxtpx>atemp"`

改为

  1. Temperature int `xml:"extensions>TrackPointExtension>atemp"`

在playground中，这是一个工作副本。

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"encoding/xml"
  6. )
  8. type Gpx struct {
  9.     Creator string `xml:"creator,attr"`
  10.     Time string `xml:"metadata>time"`
  11.     Title string `xml:"trk>name"`
  12.     TrackPoints []TrackPoint `xml:"trk>trkseg>trkpt"`
  13. }
  15. type TrackPoint struct {
  16.     Lat float64 `xml:"lat,attr"`
  17.     Lon float64 `xml:"lon,attr"`
  18.     Elevation float32 `xml:"ele"`
  19.     Time string `xml:"time"`
  20.     Temperature int `xml:"extensions>TrackPointExtension>atemp"`
  21. }
  23. func main() {
  24. 	data := `<gpx creator="StravaGPX" version="1.1" xmlns="http://www.topografix.com/GPX/1/1" 
  26. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd" xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1" xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3">
  27.  <metadata>
  28.   <time>2013-02-16T10:11:25Z</time>
  29.  </metadata>
  30.  <trk>
  31.   <name>Demo Data</name>
  32.   <trkseg>
  33.    <trkpt lat="51.6395658" lon="-3.3623858">
  34.     <ele>111.6</ele>
  35.     <time>2013-02-16T10:11:25Z</time>
  36.     <extensions>
  37.      <gpxtpx:TrackPointExtension>
  38.       <gpxtpx:atemp>8</gpxtpx:atemp>
  39.       <gpxtpx:hr>136</gpxtpx:hr>
  40.       <gpxtpx:cad>0</gpxtpx:cad>
  41.      </gpxtpx:TrackPointExtension>
  42.     </extensions>
  43.    </trkpt>
  44.   </trkseg>
  45.  </trk>
  46. `
  47. 	g := &Gpx{}
  48. 	_ = xml.Unmarshal([]byte(data), g)
  49. 	fmt.Printf("len: %d\n", len(g.TrackPoints))
  50. 	fmt.Printf("temp: %v\n", g.TrackPoints[0].Temperature)
  51. }
英文:

You're targeting a namespace instead of a variable name in your TrackPoint.Temperature xml instructions.

Change

  1. Temperature int `xml:&quot;extensions&gt;gpxtpx&gt;atemp&quot;`

To

  1. Temperature int `xml:&quot;extensions&gt;TrackPointExtension&gt;atemp&quot;`

<a href="http://play.golang.org/p/992Ozf7fn1">Here's a working copy</a> in the playground.

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;encoding/xml&quot;
  6. 	)
  8. type Gpx struct {
  9.     Creator string `xml:&quot;creator,attr&quot;`
  10.     Time string `xml:&quot;metadata&gt;time&quot;`
  11.     Title string `xml:&quot;trk&gt;name&quot;`
  12.     TrackPoints []TrackPoint `xml:&quot;trk&gt;trkseg&gt;trkpt&quot;`
  13. }
  15. type TrackPoint struct {
  16.     Lat float64 `xml:&quot;lat,attr&quot;`
  17.     Lon float64 `xml:&quot;lon,attr&quot;`
  18.     Elevation float32 `xml:&quot;ele&quot;`
  19.     Time string `xml:&quot;time&quot;`
  20.     Temperature int `xml:&quot;extensions&gt;TrackPointExtension&gt;atemp&quot;`
  21. }
  23. func main() {
  24. 	data := `&lt;gpx creator=&quot;StravaGPX&quot; version=&quot;1.1&quot; xmlns=&quot;http://www.topografix.com/GPX/1/1&quot; 
  26. xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot; xsi:schemaLocation=&quot;http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd&quot; xmlns:gpxtpx=&quot;http://www.garmin.com/xmlschemas/TrackPointExtension/v1&quot; xmlns:gpxx=&quot;http://www.garmin.com/xmlschemas/GpxExtensions/v3&quot;&gt;
  27.  &lt;metadata&gt;
  28.   &lt;time&gt;2013-02-16T10:11:25Z&lt;/time&gt;
  29.  &lt;/metadata&gt;
  30.  &lt;trk&gt;
  31.   &lt;name&gt;Demo Data&lt;/name&gt;
  32.   &lt;trkseg&gt;
  33.    &lt;trkpt lat=&quot;51.6395658&quot; lon=&quot;-3.3623858&quot;&gt;
  34.     &lt;ele&gt;111.6&lt;/ele&gt;
  35.     &lt;time&gt;2013-02-16T10:11:25Z&lt;/time&gt;
  36.     &lt;extensions&gt;
  37.      &lt;gpxtpx:TrackPointExtension&gt;
  38.       &lt;gpxtpx:atemp&gt;8&lt;/gpxtpx:atemp&gt;
  39.       &lt;gpxtpx:hr&gt;136&lt;/gpxtpx:hr&gt;
  40.       &lt;gpxtpx:cad&gt;0&lt;/gpxtpx:cad&gt;
  41.      &lt;/gpxtpx:TrackPointExtension&gt;
  42.     &lt;/extensions&gt;
  43.    &lt;/trkpt&gt;
  44.   &lt;/trkseg&gt;
  45.  &lt;/trk&gt;
  46. `
  47. 	g := &amp;Gpx{}
  48. 	_ = xml.Unmarshal([]byte(data), g)
  49. 	fmt.Printf(&quot;len: %d\n&quot;, len(g.TrackPoints))
  50. 	fmt.Printf(&quot;temp: %v\n&quot;, g.TrackPoints[0].Temperature)
  51. }

huangapple
  • 本文由 发表于 2013年2月19日 06:35:23
  • 转载请务必保留本文链接：https://go.coder-hub.com/14946566.html
  • go
  • xml
  • xml-parsing
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