仅对Golang中的匹配字段取消编组innerxml

Question

If I have the following XML:

<blah>
  <a>stuff here</a>
  <b>other stuff</b>
  <b>more stuff</b>
</blah>

I'd like to be able to unmarshal the innerxml of <blah>, but only include the <b> elements and all raw tags, and exclude everything else. In this example, my raw innerxml result needs to be:

<b>other stuff</b>
<b>more stuff</b>

Not sure if this is doable with struct tags or if I have to write a custom unmarshaler function.

Tried the following code:

package main

import (
    "encoding/xml"
    "fmt"
)

type blah struct {
    XMLName xml.Name `xml:"blah"`
    RawXML  string   `xml:",innerxml"`
}

func main() {

    blahXML := []byte(`<blah>
    <a>stuff here</a>
    <b>other stuff</b>
    <b>more stuff</b>
</blah>`)

    var blah blah

    if err := xml.Unmarshal(blahXML, &blah); err != nil {
        panic(err)
    }

    fmt.Printf("%s
", blah.RawXML)
}

Which returns all of the innerxml:

<a>stuff here</a>
<b>other stuff</b>
<b>more stuff</b>

Not sure how to just return the raw <b> lines.

Thanks!

Answer 1

If you want the inner XML of an element, that will be everything inside that element. You can't choose specific elements and still call it inner XML; that's not how XML parsers work. It seems like what you actually want is the outer XML of all the b elements in the document. That's relatively easy, once you look at it from the right perspective. I'd suggest just unmarshalling the b elements, and if you want to reconstruct the XML with only those elements, just marshal it again:

type blah struct {
    XMLName xml.Name `xml:"blah"`
    Bees    []b      `xml:"b"`
}

type b struct {
    RawXML string `xml:",innerxml"`
}

func main() {
    blahXML := []byte(`<blah>
    <a>stuff here</a>
    <b>other stuff</b>
    <b>more stuff</b>
</blah>`)
    test := new(blah)
    err := xml.Unmarshal(blahXML, test)
    if err != nil {
        panic(err)
    }
    output, err := xml.Marshal(&test)
    if err != nil {
        panic(err)
    }
    fmt.Println(string(output))
}

Playground example here: https://play.golang.org/p/MAtWk2YMld