Restconf server does NOT support multiple key requests on list nodes.

[Pawel-Guzik]

Side Note: Below bug report based on GET request, but this case also applies to DELETE

---

Actual behavior
In the case of the Yang node request with multiple key values, restconf server response contains only resource coupled with the first key.

• Considering the following request
  GET .../<list_node>=<key_1>,<key_2>,...,<key_n>
• Server responds with:
  {<key_1_resource_value>}

---

Expected behavior
In the case of the Yang node request with multiple key values, restconf server response contains all resources coupled with each requested key.

• Considering the following request
  GET .../<list_node>=<key_1>,<key_2>,...,<key_n>
• Server responds with:
  {<key_1_resource_value>, <key_2_resource_value>,...,<key_n_resource_value>}

---

Reproduction steps
Code used to reproduce the bug can be found in the section below

1. Start restconf server - go run main.go
2. Create more than 1 resource within the books Yang node (it is already done, by configuration within startup.json file)
3. Perform read request, requesting more than 1 resource from the books list-node
   Request:
   curl -X GET http://localhost:8080/restconf/data/library:books=0,1
   Response:
   {"book-id":0,"title":"Book nr 0"}

---

Code used to reproduce a bug
yang/library.yang

module library {
	revision 2024-10-03;  
	      list books {
	      key book-id;
      
              leaf book-id {
	          description "unique id for book";
                  type int32;
              }
      
              leaf title {
	          description "title of the book";
                  type string;
              }
	}
}

main.go

package main

import (
	"github.com/freeconf/restconf"
	"github.com/freeconf/restconf/device"
	"github.com/freeconf/yang/fc"
	"github.com/freeconf/yang/nodeutil"
	"github.com/freeconf/yang/source"
)

type Book struct {
	BookId int
	Title  string
}

type Library struct {
	Books []*Book
}

type Model struct {
	Library *Library
}

func NewLibrary() *Library {
	lib := &Library{
		Books: []*Book{},
	}
	return lib
}

func main() {
	fc.DebugLog(true)
	ypath := source.Any(source.Path("yang"), restconf.InternalYPath)
	d := device.New(ypath)
	rootNode := &nodeutil.Node{Object: NewLibrary()}
	d.Add("library", rootNode)
	restconf.NewServer(d)
	d.ApplyStartupConfigFile("./startup.json")
	select {}
}

startup.json

{
    "fc-restconf": {
        "web": {
            "port": ":8080"
        }
    },
    "library": {
        "books": [
            {
                "book-id": 0,
                "title": "Book nr 0"
            },
            {
                "book-id": 1,
                "title": "Book nr 1"
            }
        ]
    }
}

---

Additional informations
Related RESTCONF rfc section - https://datatracker.ietf.org/doc/html/rfc8040#section-3.5.3
go.mod content:

module multiplekeys

go 1.23.0

require (
	github.com/freeconf/restconf v0.0.0-20240627124255-9543e7933a6e // indirect
	github.com/freeconf/yang v0.0.0-20240126135339-ef92ddeb9f99 // indirect
)