在Go中解组xml时省略空数组元素

Question

I try to unmarshal an xml array where I want to omit empty elements.

I would expect the following code to print 2, as the second bar element is empty. Instead 3 is printed.

package main

import (
    "fmt"
    "encoding/xml"
    "bytes"
)

type foo struct {
    Bars []string `xml:"bar,omitempty"`
}

func main() {
    xmlStr := `
        <foo>
            <bar>1</bar>
            <bar></bar>
            <bar>2</bar>
        </foo>`

    var f foo
    xml.NewDecoder(bytes.NewBufferString(xmlStr)).Decode(&f)
    fmt.Println(len(f.Bars))
}

Go playground link: https://play.golang.org/p/co8QxkyKTv

Answer 1

Unless you want to get into xml.Unmarshaler dark magic, I'd suggest just do

func compact(ss []string) []string {
    res := make([]string, 0, len(ss))
    for _, s := range ss {
        if s != "" {
            res = append(res, s)
        }
    }
    return res
}