Golang-将XML时间编组为XML属性的时间作为日期格式

Question

I'm trying to format a custom time type, Date, that implements the Marshaler interface and simply formats itself as "2006-01-02" when written as XML.

type Person struct {
    ...
    DateOfBirth           Date      `xml:"DOB,attr"`
    ...
}

type Date time.Time

func (d Date) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
    dateString := fmt.Sprintf("\"%v\"", time.Time(d).Format("2006-01-02"))    
    e.EncodeElement(dateString, start)

    return nil
}

I was using this SO as a reference, but the error - &xml.UnsupportedTypeError{Type:(*reflect.rtype)} - is thrown.

I'm missing something, any ideas?

Answer 1

You are implementing the wrong interface.

Since the Date type is meant to be marshaled as an attribute (as shown from the xml:"DOB,attr" tag), it needs to implement the xml.MarshalerAttr interface:

type MarshalerAttr interface {
    MarshalXMLAttr(name Name) (Attr, error)
}

So you probably need to add code like this:

func (d Date) MarshalXMLAttr(name xml.Name) (xml.Attr, error) {
    dateString := time.Time(d).Format("2006-01-02")    
    attr := xml.Attr {
        name,
        dateString,
    }

    return attr, nil
}

Note that I removed the apparently unnecessary quotes from the value string.