How to retrieve/print the final YAML string after YAML files are loaded and merged?

[Bright Zheng]

This is NOT a bug, instead, it's an ask.

It's common to load some YAML files and merge them to generate a so-called "effective" YAML and then print it out.
But I don't know how to print it out as a valid YAML string.

Is there an API to do something like k.ToString() to print out the Koanf object as a YAML string after files are merged?

[Rohan Verma]

You can maybe do something like this?

package main

import (
	"log"

	"github.com/knadh/koanf/parsers/yaml"
	"github.com/knadh/koanf/providers/rawbytes"
	"github.com/knadh/koanf/v2"
)

var k = koanf.New(".")

func main() {
	log.Println(k.Load(rawbytes.Provider([]byte(`key1: val
name1: test
number1: 2`)), yaml.Parser()))

	k.Print()

	log.Println(k.Load(rawbytes.Provider([]byte(`key2: val
name2: test
number2: 2`)), yaml.Parser()))

	k.Print()

	b, _ := k.Marshal(yaml.Parser())
	log.Println("result\n", string(b))
}

2023/11/17 13:49:04 <nil>
key1 -> val
name1 -> test
number1 -> 2
2023/11/17 13:49:04 <nil>
key1 -> val
key2 -> val
name1 -> test
name2 -> test
number1 -> 2
number2 -> 2
2023/11/17 13:49:04 result
 key1: val
key2: val
name1: test
name2: test
number1: 2
number2: 2

[Bright Zheng]

Cool, that works for me. Thank you @rhnvrm!

Not sure whether it's a good idea to have a new API like:

// ToString takes a Parser implementation and generate the config map into string,
// for example, to TOML or JSON string.
func (ko *Koanf) ToString(p Parser) (string, error) {
	bytes, err := p.Marshal(ko.Raw())
	if err != nil {
		return "", err
	}
	return string(bytes), nil
}

[Rohan Verma]

I think the current API should suffice as the ToString method would just be a utility func that converts the output to string.

https://github.com/knadh/koanf#unmarshalling-and-marshalling

[Kailash Nadh]

k.Sprint() returns the human readable form.

You can also marshal to YAML, TOML etc. See https://github.com/knadh/koanf#unmarshalling-and-marshalling

[Bright Zheng]

I think it's fine for me now as long as I know how to generate the YAML string from the object.
And maybe this thread may help others who are curious.