nmtokenExample.go

package main

/*
Description:
Parsing an NMTOKENS XML tag into a slice of strings 
*/
import (
	"encoding/xml"
	"strings"
	"time"
)

// The NMTOKENS type
type Nmtokens []string

// Override default unmarshaling to parse a string from the tag body, into an slice of
// strings
func (t *Nmtokens) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	var v string
    // Get the tag body as a string
	if err := d.DecodeElement(&v, &start); err != nil {
		return err
	}

	*t = strings.Fields(v)
	return nil
}

// Override default unmarshaling of attribute
func (t *Nmtokens) UnmarshalXMLAttr(attr xml.Attr) error {
	*t = strings.Fields(attr.Value)
	return nil
}


// Usage:
/*
Assuming the following XSD schema:
    <xs:element name="postMetadata">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="labels" type="xs:NMTOKENS"/>
                <xs:element name="createDate" type="xs:dateTime"/>
            </xs:sequence>
	    <xs:attribute name="authors" type="xs:NMTOKENS"/>
        </xs:complexType>
    </xs:element>
*/

type PostMetedata struct {
	Authors    Nmtokens  `xml:"authors,attr"`
	Labels     Nmtokens  `xml:"labels"`
	CreateDate time.Time `xml:"createDate"`
}


func main() {
	// our XML as a byte array
	xmlBytes := []byte(`<xsd:postMetadata authors="someone someone-else">
    <labels>programming go-lang XML</labels>
    <createDate>2018-07-08T15:52:58Z</createDate>
</postMetadata>`)

	var postData PostMetedata
	xml.Unmarshal(xmlBytes, &postData)

	// Print all labels, each in single line
	println("Labels:")
	for _, label := range postData.Labels {
		println("- " + label)
	}

	// Print all autors, each in single line
	println("Authors:")
	for _, author := range postData.Authors {
		println("- " + author)
	}
}

/*
Output

Labels:
- programming
- go-lang
- XML
Authors:
- someone
- someone-else

*/