接口和encoding / xml解组

Question

I have a soap service I'm writing against. One portion of the soap API is for returning a query result, and I'm hoping to provide the base structs for decoding the envelope, while allow a developer to fill in the interface in which encoding/xml will decode to.

type QueryEnvelope struct {
    XMLName xml.Name   `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`
    Body    *QueryBody `xml:"http://schemas.xmlsoap.org/soap/envelope/ Body"`
}

type QueryBody struct {
    QueryResult *QueryResult `xml:"queryResponse>result"`
}

type QueryResult struct {
    Done    bool    `xml:"done"`
    Size    int     `xml:"size"`
    Records Record `xml:"records"`
}

type Record interface {
    UnmarshalXML(d *xml.Decoder, start xml.StartElement) error
}

Is it possible to inject an interface like this for unmarhsalling or do I have to accept the interface at the QueryEnvelope{} level?

Ideally client side would act as such:

type Record struct {
     Id int `xml:"id"`,
     Name stirng `xml:"name"`
}

func (r *Record) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
     // unmasrshal here, or best case I dont even need to implment UnmarsahlXML()!
}
res, err := Query("select id from table", Record{})

This would mean that they don't have to reproduce the QueryEnvelope struct (as a developer using the package I'm creating)

Answer 1

So you can indeed inject an interface partway through, I was failing it allocate memory for the decoder to work:

Package:

type QueryEnvelope struct {
    XMLName xml.Name   `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`
    Body    *QueryBody `xml:"http://schemas.xmlsoap.org/soap/envelope/ Body"`
}

type QueryBody struct {
    QueryResult *QueryResult `xml:"queryResponse>result"`
}

type QueryResult struct {
    Done    bool        `xml:"done"`
    Size    int         `xml:"size"`
    Records interface{} `xml:"records"`
}

func (r *Resource) Query(sql string, r interface{}) error {
    t := &QueryEnvelope{Body: &QueryBody{QueryResult: &QueryResult{Records: r}}}
    //do query and unmarshal into t
    return err
}

Client / main:

type Record struct {
    Id   string `xml:"id"`
    Name string `xml:"name"`
}

r := new([]*Record) // must allocate memory using new
err = ent.Query("select id, name from account limit 3", r)