krystal/go-katapult

package buildspec

import (
    "encoding/xml"
    "fmt"
)

type User struct {
    ID           string `json:"id,omitempty" yaml:"id,omitempty"`
    EmailAddress string `json:"email_address,omitempty" yaml:"email_address,omitempty"`
}

func (s *User) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
    x := &xmlUser{}

    switch {
    case s.ID != "":
        x.Value = s.ID
    case s.EmailAddress != "":
        x.By = "email_address"
        x.Value = s.EmailAddress
    }

    return e.EncodeElement(x, start)
}

func (s *User) UnmarshalXML(
    d *xml.Decoder,
    start xml.StartElement,
) error {
    x := &xmlUser{}
    _ = d.DecodeElement(&x, &start)

    v := User{}

    switch {
    case x.By == "":
        v.ID = x.Value
    case x.By == "email_address":
        v.EmailAddress = x.Value
    default:
        return fmt.Errorf(
            `%w: User by="%s" is not supported`, ErrParseXML, x.By,
        )
    }

    *s = v

    return nil
}

type xmlUser xmlLookupElem

type xmlUsers struct {
    All   string  `xml:"all,attr,omitempty"`
    Users []*User `xml:"User,omitempty"`
}