dumping is formating custom type wrong

[rubendmatos1985]

const yaml = require("js-yaml")

class Test {
  constructor(id) {
    this.id = id
  }
  id

  get Id() {
    return this.id
  }
  async fetchData() {
    console.log("get async data")
  }
}



var customtagYamlType = new yaml.Type("!mapInfo", {
  kind: "scalar",
  resolve: () => true,
  construct: (id) => new Test(id),
  instanceOf: Test,
  represent: (customTag) => customTag.id,
})

const obj = {
  name: 'some',
  data:{
    content:[
      {
        value: new Test("1")
      }
    ]
  }
}


const schema = yaml.Schema.create([customtagYamlType])

const result = yaml.dump(obj, { schema })
console.log(result)

/* the output is 
data:
  content:
  - value: !<!mapInfo> '1'

-----------------------------------------
i am expecting like in the documentation
data:
  content:
  - value: !mapInfo  '1'



node version v12.14.1
  

*/

[rlidwka]

Those string representations are equivalent:

console.log(yaml.load(`
a: !<!mapInfo> '1'
b: !mapInfo '1'
`, { schema }))

// prints { a: Test { id: '1' }, b: Test { id: '1' } }

!<!mapInfo> is a global version of the application-local tag !mapInfo, both variants are acceptable I believe.

Does it cause any issues (e.g. interoperability with other parsers)?

[rubendmatos1985]

Yes they are equivalent but the same library throw an error when convert from !mapInfo to !<!mapInfo> and i try to convert again to json. My example to get in context is that i am making an app which convert Yaml to Json shows a UI where you can edit the content and after that will convert the json again to YAML. I have to use string.replace('!<!mapInfo>', '!mapInfo' ) after dumping. It is working fine but if the object is to long with a lot of custom tags i will compromise the perfromance of the app

[danmactough]

+1 I am also working on a library where I want to be able to load yaml with custom tags, process/transform the data, and then dump the transformed data as yaml while preserving the original -- I want to be able to perform a diff and don't want every custom tag rewritten.

If we had an option available when creating a Type (for example, a boolean flag -- dumpTagsWithGlobalWrapper), it seems like here, we could propagate that option to the state with something like state.dumpTagsWithGlobalWrapper = !!type.dumpTagsWithGlobalWrapper. Then where we currently add that wrapper here, we could conditionally add the wrapper or not.

Would you accept a PR for this?

[rlidwka]

Fixed in a0d0caa (currently in dev branch).

Now tag behavior aligns with pyyaml, where custom tags are dumped as !tag, and there is no way to dump those as !<!tag>. Please tell me if there's any use-case for the old behavior.

Duplicate of:
#364
#187