Nested lookup failing

[urso]

go-ucfg supports lookup based on the result string value. Lookup fails when the final expansion is an object, but still works if the target is a primitive value.

Test program:

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os"

	"github.com/elastic/beats/libbeat/common"
)

func main() {
	files := os.Args[1:]
	cfg, err := common.LoadFiles(files...)
	if err != nil {
		log.Fatal(err)
	}

	tmp := map[string]interface{}{}
	if err := cfg.Unpack(&tmp); err != nil {
		log.Fatal(err)
	}

	b, err := json.MarshalIndent(tmp, "", "    ")
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s\n", b)
}

First test file (a.yml):

setting: ${${select}}
select: test
test: a

Second test file (b.yml):

setting: ${${select}}
select: test
test:
  key: value

Expected output:

$ go run main.go a.yml
{
    "select": "test",
    "setting": "a",
    "test": "a"
}
$ go run main.go b.yml
{
    "select": {
        "key": "value",
    },
    "setting": "a",
    "test": {
        "key": "value"
     }
}

Actual output:

go run main.go a.yml
{
    "select": "test",
    "setting": "a",
    "test": "a"
}
$ go run main.go b.yml
2020/02/22 09:46:45 type mismatch accessing 'setting' (source:'b.yml')
exit status 1