正确的结构布局以解析Go中的xml

Question

Trying to parse some nmap data with golang, but the layout of my structs isn't quite working. Link to code on playground: https://play.golang.org/p/kODRGiH71W

package main

import (
    "encoding/xml"
    "fmt"
)

type Extrareasons struct {
    Reason string `xml:"reason,attr"`
    Count  uint32 `xml:"count,attr"`
}

type Extraports struct {
    State  string       `xml:"state,attr"`
    Count  uint32       `xml:"count,attr"`
    Reason Extrareasons `xml:"extrareasons"`
}

type StateProps struct {
    State  string `xml:"state,attr"`
    Reason string `xml:"reason,attr"`
}

type PortProps struct {
    Protocol string `xml:"protocol,attr"`
    Port     uint32 `xml:"portid,attr"`
    StateStuff StateProps `xml:"state"`
}

type PortInfo struct {
    Extra    Extraports `xml:"extraports"`
    PortProp PortProps  `xml:"port"`
}

type Ports struct {
    Port PortInfo `xml:"ports"`
}

func main() {
    xmlString := `<ports>
         <extraports state="closed" count="64">
            <extrareasons reason="conn-refused" count="64" />
         </extraports>
         <port protocol="tcp" portid="22">
            <state state="open" reason="syn-ack" reason_ttl="0" />
            <service name="ssh" method="table" conf="3" />
         </port>
      </ports>`

    var x Ports
    if err := xml.Unmarshal([]byte(xmlString), &x); err == nil {
        fmt.Printf("%+v
", x)
    } else {
        fmt.Println("err:", err)
    }

}

$ go run test.go 
{Port:{Extra:{State: Count:0 Reason:{Reason: Count:0}} PortProp:{Protocol: Port:0 StateStuff:{State: Reason:}}}}

Answer 1

The layer that the Ports wrapper struct creates is unnecessary, drop it. You only need to model the contents of the root xml element which is <ports> and its content is described / modeled by PortInfo. There is no need for a type that wraps the root element.

Simply change

var x Ports

to

var x PortInfo 

And it will work. Try it on the Go Playground. Output (wrapped):

{Extra:{State:closed Count:64 Reason:{Reason:conn-refused Count:64}}
    PortProp:{Protocol:tcp Port:22 StateStuff:{State:open Reason:syn-ack}}}