Marshal From yaml.Node gives invalid Yaml

[will7200]

Summary

Reading a valid yaml spec into a yaml.Node and then Marshalling doesn't produce valid yaml.

Occurrence

Go version: go1.12.3 windows/amd64
Branch: v3
Commit: cdc409d

Example

package main

import (
    "fmt"
    "log"

    "gopkg.in/yaml.v3"
)

var (
    sourceYaml = `version: 1
type: verbose
kind : bfr

# my list of applications
applications:

#  First app
  - name: app1
    kind: nodejs
    path: app1
    exec:
      platforms: k8s
      builder: test
`
)

func main() {
    t := yaml.Node{}

    err := yaml.Unmarshal([]byte(sourceYaml), &t)
    if err != nil {
        log.Fatalf("error: %v", err)
    }

    b, err := yaml.Marshal(&t)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(string(b))
}

Produces the following yaml

version: 1
type: verbose
kind: bfr


# my list of applications
applications:
-   #  First app
name: app1
    kind: nodejs
    path: app1
    exec:
        platforms: k8s
        builder: test

Expected yaml

version: 1
type: verbose
kind: bfr


# my list of applications
applications:
-   #  First app
    name: app1
    kind: nodejs
    path: app1
    exec:
        platforms: k8s
        builder: test

[niemeyer]

I believe this has been fixed shortly after the release with fc85683.

Will close this, but please reopen if you can reproduce after ensuring your tree is up to date.

[will7200]

Here is my go.mod

module retainyamlcommments

go 1.12

require (
	github.com/davecgh/go-spew v1.1.1 // indirect
	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
	gopkg.in/yaml.v3 v3.0.0-20190409140830-cdc409dda467
)

Please correct me if I am wrong, but this is the latest commit.

[will7200]

@niemeyer Cannot Reopen for whatever reason

[SofiaTa]

@niemeyer - we also took the latest cdc409dc commit which include fc85683 and the issue is persist, can you please re-open it ? since it doesn't work ( I verify that the new code if !first || emitter.states[len(emitter.states)-1] != yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE { is there but it doesnt works) is there some workaround ?

[niemeyer]

Thanks, I'll look into it.

[niemeyer]

This should have been fixed by 55513ca. Please let me know if you you find any other issues.

[RaynDol]

@niemeyer - im trying to run the program with the issue against commit 55513cacd4ae8b250e3a9084ab9d8c407b1ed618 and getting the exact same result , i.e. the yaml is still looks the same and invalid ...Do I miss something ? I just run the program in the post

[niemeyer]

@RaynDol If you're getting the exact same result you're just not running the right code. I've copy & pasted the logic and can go back and forth between the two revisions and get the error or not depending on which revision I'm running.

[RaynDol]

@niemeyer - not sure that I got you, I use the latest version see go.mod

module mta_parse

go 1.12

require gopkg.in/yaml.v3 v3.0.0-20190502103701-55513cacd4ae

and run the following code which includes valid yaml

package main

import (
	"fmt"
	"log"

	"gopkg.in/yaml.v3"
)

var (
	sourceYaml = `version: 1
type: verbose
kind : bfr

# my list of applications
applications:

#  First app
  - name: app1
    kind: nodejs
    path: app1
    exec:
      platforms: k8s
      builder: test
`
)

func main() {
	t := yaml.Node{}

	err := yaml.Unmarshal([]byte(sourceYaml), &t)
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	b, err := yaml.Marshal(&t)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(b))
}

The output is

version: 1
type: verbose
kind: bfr


# my list of applications
applications:
  - #  First app
    name: app1
    kind: nodejs
    path: app1
    exec:
        platforms: k8s
        builder: test


Process finished with exit code 0

what am I missing ? does it works for you ?

please see that the comment is starting the array as before ....

expected yaml

 #  First app
 -  name: app1
    kind: nodejs
    path: app1
    exec:
        platforms: k8s
        builder: test

if I remove the comment (first app) it looks ok, but with the comment change the yaml to invalid yaml

[niemeyer]

@RaynDol That's not the exact same output, and that's valid yaml that represents the same data that was marshalled.

I'm happy to evolve the formatting so comments are placed in the locations most people would appreciate, but that's neither the same output nor invalid, so separate issue.

[RaynDol]

@niemeyer - Thanks, I've opend the following issue. it will be great if you can have a look

#459

Thanks a lot for your hard work! V3 features are superb!