Disable tag support

[novln]

Hello,

Is it possible to disable tag support with UnmarshalWithConf so we could unmarshal a konf instance to a struct without having to provides tags?

Reference: https://github.com/knadh/koanf/blob/master/koanf.go#L199

Like adding a new field called DisableTag as a boolean (in order to avoid compatibility break).

Let me know what you think.
Thank you in advance.

[knadh]

koanf uses the mapstructure package to do the unmarshalling. Looks like mapstructure implicitly behaves the way you described. That is, if there's no tag on a struct field, it unmarshals it any way. I'll investigate more and document this behaviour.

package main

import (
	"fmt"
	"log"

	"github.com/knadh/koanf"
	"github.com/knadh/koanf/parsers/json"
	"github.com/knadh/koanf/providers/file"
)

func main() {
	var k = koanf.New(".")

	// struct with no 'koanf' tags.
	type test struct {
		Type string
	}

	// Load JSON config.
	if err := k.Load(file.Provider("mock/mock.json"), json.Parser()); err != nil {
		log.Fatalf("error loading config: %v", err)
	}

	var out test
	k.Unmarshal("", &out)

	fmt.Println(out)
}

[novln]

Oh, okay. It's kind of misleading 😕
Thank you for the explanation, and yeah, some comments on this behavior would be great.

[rhnvrm]

Added a wiki entry to document this: https://github.com/knadh/koanf/wiki#mapstructure