Marshall map to XML in Go

Question

I'm trying to output a map as XML data, however I receive the following error:

xml: unsupported type: map[string]int

Marshalling maps works fine for JSON so I don't get why it wouldn't work the same for XML. Is using a Struct really the only way?

Answer 1

I ended up solving this by using the xml.Marshaler as suggested by Dave C

// StringMap is a map[string]string.
type StringMap map[string]string

// StringMap marshals into XML.
func (s StringMap) MarshalXML(e *xml.Encoder, start xml.StartElement) error {

    tokens := []xml.Token{start}

    for key, value := range s {
        t := xml.StartElement{Name: xml.Name{"", key}}
        tokens = append(tokens, t, xml.CharData(value), xml.EndElement{t.Name})
    }

    tokens = append(tokens, xml.EndElement{start.Name})

    for _, t := range tokens {
        err := e.EncodeToken(t)
        if err != nil {
            return err
        }
    }

    // flush to ensure tokens are written
    return e.Flush()
}

_{Source: https://gist.github.com/jackspirou/4477e37d1f1c043806e0}

Now the map can be marshalled by simply calling

output, err := xml.MarshalIndent(data, "", "  ")