Yaml: MarshalYAML doesn't call MarshalYAML on returned value

Created on 16 Oct 2015 · 7Comments · Source: go-yaml/yaml

From reading the docs, I'd expect the following example to print "something",
but it prints "y": 99 instead.

package main

import (
    "fmt"
    "log"
    "gopkg.in/yaml.v2"
)

func main() {
    t := T{99}
    data, err := yaml.Marshal(t)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("%s\n", data)
}

type T struct {
    X int
}

func (t T) MarshalYAML() (interface{}, error) {
    return S{t.X}, nil
}

type S struct {
    Y int
}

func (s S) MarshalYAML() (interface{}, error) {
    return "something", nil
}

Source

rogpeppe

👍1

Most helpful comment

Why MarshalYAML method of Marshaler interface returns interface{} rather than []byte like in encoding/json ?

josephbuchma on 30 Mar 2016

👍7

All 7 comments

Interested in offering a patch for this?

niemeyer on 16 Oct 2015

I am interested in getting this fixed too. +1

sigmonsays on 12 Nov 2015

I'd love to do a patch but there are at least 10 things that I need to do more than this that I know no-one else is ever going to do... Perhaps on a flight sometime, unless I find this bug blocking some other task.

rogpeppe on 13 Nov 2015

Why MarshalYAML method of Marshaler interface returns interface{} rather than []byte like in encoding/json ?

josephbuchma on 30 Mar 2016

👍7

We ran into this. Is this something you'd consider a bug or just inaccurate documentation?