在GOlang中将XML编组：字段为空（APPEND不起作用？）

Question

i'm learning to create XML in Go. Here's my code:

type Request struct {
    XMLName       xml.Name        `xml:"request"`
    Action        string          `xml:"action,attr"`
    ...
    Point         []point         `xml:"point,omitempty"`
}

type point struct {
    geo    string `xml:"point"`
    radius int    `xml:"radius,attr"`
}

func main() {
    v := &Request{Action: "get-objects"}
    v.Point = append(v.Point, point{geo: "55.703038, 37.554457", radius: 10})
    output, err := xml.MarshalIndent(v, "  ", "    ")
    if err != nil {
        fmt.Println("error: %v
", err)
    }
    os.Stdout.Write([]byte(xml.Header))
    os.Stdout.Write(output)

}

I expect the output to be like:

<?xml version="1.0" encoding="UTF-8"?>
  <request action="get-objects">
      <point radius=10>55.703038, 37.554457</point>
  </request>

But what I'm getting is:

 <?xml version="1.0" encoding="UTF-8"?>
      <request action="get-objects">
          <point></point>
      </request>

What am I missing or doing wrong? Because the "name,attr" thing works perfect for everything else (for example, for the "request" field, as you can see). Thanks.

Answer 1

Several things are wrong in your code. When working with encoding packages in Go, all the fields you want to marshal/unmarshal have to be exported. Note that the structs themselves do not have to be exported.

So, first step is to change the point struct to export the fields:

type point struct {
    Geo    string `xml:"point"`
    Radius int    `xml:"radius,attr"`
}

Now, if you want to display the Geo field inside a point, you have to add ,cdata to the xml tag. Finally, there is no need to add an omitempty keyword to a slice.

type Request struct {
    XMLName xml.Name `xml:"request"`
    Action  string   `xml:"action,attr"`
    Point   []point  `xml:"point"`
}

type point struct {
    Geo    string `xml:",chardata"`
    Radius int    `xml:"radius,attr"`
}

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