please make Response.Unmarshal to accept io.Reader

[isaacwein]

Please make Response.Unmarshal to accept io.Reader
it is better for performance if the xml.decoder gets a large http repose, it can read it directly from the socket rather then converting the whole response body with io.ReadAll(resp.body) to memory and then passing it to the xml.decoder

this is how I need to do it now

body := []byte(`xml-rpc code`)

err = xmlrpc.Response(body).Unmarshal(&resData)

this is how it will be used after

body := strings.NewReader(`xml-rpc-code`)

err = xmlrpc.Response(body).Unmarshal(&resData)

[icholy]

The tricky part here would be fault detection

xmlrpc/response.go

Lines 26 to 32 in 3377102

	if !faultRx.Match(r) {
	return nil
	}
	var fault FaultError
	if err := unmarshal(r, &fault); err != nil {
	return err
	}

We could potentially use a bufio.Reader to peek at the first N bytes of the stream and use that to figure out if there was a fault.

[isaacwein]

Bufio.reader will defeat the whole purpose of leaving it as a stream The only way todo it to use the xml.unmarshaler interface So if it has a property error it should decide error if not try to decode the success data

…

On Sun, Sep 18, 2022 at 8:34 PM Ilia Choly ***@***.***> wrote: The tricky part here would be fault detection https://github.com/kolo/xmlrpc/blob/3377102c83bd60413083d5c738173f7db6160698/response.go#L26-L32 We could potentially use a bufio.Reader to peek at the first N bytes of the stream and use that to figure out if there was a fault. — Reply to this email directly, view it on GitHub <#80 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AIIO4JGC4DDNJJ33IIH5OF3V66YHVANCNFSM5TPFI6CA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[icholy]

Bufio.reader will defeat the whole purpose of leaving it as a stream

Why do you say that? There's no way to avoid using one when using the encoding/xml package.
See: https://cs.opensource.google/go/go/+/refs/tags/go1.19.1:src/encoding/xml/xml.go;l=375;drc=63d05642d48ec81637481518df962f2b3be435a3

[isaacwein]

I will try to make a demo it might take a day or Two

…

On Sun, Sep 18, 2022 at 10:38 PM Ilia Choly ***@***.***> wrote: Bufio.reader will defeat the whole purpose of leaving it as a stream Why do you say that? There's no way to avoid using one when using the encoding/xml package. — Reply to this email directly, view it on GitHub <#80 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AIIO4JC2RVTL4AFYI3MNEHLV67GZNANCNFSM5TPFI6CA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[isaacwein]

you make a struct liket this

type respData struct {
	Suc any        `xmlrpc:"suc"` // here will go the success data that that need to pe decoded on
	Err *XmlRpcErr `xmlrpc:"err"` // here will go the data if the response body is an error
}

now you make on it a custom UnmarshalXML method and check if the first element after <methodResponse> is <params> or <fault> that will let you know if you need to call the success decoder or the error decoder

I made a partial example go playground

package main

import (
	"encoding/xml"
	"fmt"
	"io"
	"strings"
)

// XML-RPC response success body example
var sucResp = `
<?xml version='1.0'?>
<methodResponse>
    <params>
        <param>
            <value>
                <struct>
                    <member>
                        <name>name</name>
                        <value>
                            <string>jack</string>
                        </value>
                    </member>
                </struct>
            </value>
        </param>
    </params>
</methodResponse>
`
// XML-RPC response error body example
var errorResp = `
<?xml version='1.0'?>
<methodResponse>
    <fault>
        <value>
            <struct>
                <member>
                    <name>faultCode</name>
                    <value>
                        <int>400</int>
                    </value>
                </member>
                <member>
                    <name>faultString</name>
                    <value>
                        <string>Account not found</string>
                    </value>
                </member>
            </struct>
        </value>
    </fault>
</methodResponse>
`

func main() {
	type SUC struct {
		Name string `xmlrpc:"name"`
	}
	
	fmt.Println("---- parsing on success body ----")
	err := XmlRpcDecoder(strings.NewReader(sucResp), &SUC{})
	if err != nil {
		fmt.Println("err", err)
	}
	
	fmt.Println("---- parsing on error body ----")
	err = XmlRpcDecoder(strings.NewReader(errorResp), &SUC{})
	if err != nil {
		fmt.Println("err", err)
	}
}

// XmlRpcErr XML-RPC response error
type XmlRpcErr struct {
	FaultCode   int    `xmlrpc:"faultCode"`
	FaultString string `xmlrpc:"faultString"`
}

func (e *XmlRpcErr) Error() string {
	return fmt.Sprintf("xmlrpc error: %d - %s", e.FaultCode, e.FaultString)
}

// respData XML-RPC response data that holds both success and error data
type respData struct {
	Suc any        `xmlrpc:"suc"`
	Err *XmlRpcErr `xmlrpc:"err"`
}
// UnmarshalXML checking if the xml-rpc body is a success or error
func (r *respData) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	// decode inner elements

	for {
		t, err := d.Token()
		if err != nil {
			return fmt.Errorf("getting first element error: %w",err)
		}
		//var i any
		switch tt := t.(type) {
		case xml.StartElement:
			switch tt.Name.Local {
			case "params":
				fmt.Printf("you decoding success data on r.Suc %T\n", r.Suc)
				return d.DecodeElement(r.Suc, &tt)
			case "fault":
				fmt.Printf("you decoding error data on r.Err %T\n", r.Err)
				return d.DecodeElement(r.Err, &tt)
			}

		case xml.EndElement:
			if tt == start.End() {
				return nil
			}
		}

	}
}

// XmlRpcDecoder XML-RPC response decoder
func XmlRpcDecoder(body io.Reader, sucData any) error {

	resp := &respData{Suc: sucData}

	err := xml.NewDecoder(body).Decode(resp)
	if err != nil {
		return err
	}
	if resp.Err != nil {
		return resp.Err
	}
	return nil
}

[isaacwein]

Bufio.reader will defeat the whole purpose of leaving it as a stream

Why do you say that? There's no way to avoid using one when using the encoding/xml package. See: https://cs.opensource.google/go/go/+/refs/tags/go1.19.1:src/encoding/xml/xml.go;l=375;drc=63d05642d48ec81637481518df962f2b3be435a3

sorry I am taking back my statement, I thought you wanted to read the whole body to memory and then decode it