Unity (Game Engine) Yaml parsing

Hello,

I am trying to parse meta files from the game engine Unity to Json. (For a kind of self build level editor), now I try to parse the Yaml data with JS-Yaml, but I get an error.

The following Yaml:

%YAML 1.1
%TAG !u! tag:unity3d.com,2011:
--- !u!1 &100000
GameObject:
  m_ObjectHideFlags: 0
  m_PrefabParentObject: {fileID: 0}
  m_PrefabInternal: {fileID: 100100000}
  serializedVersion: 4
  m_Component:
  - 4: {fileID: 400000}
  - 212: {fileID: 21200000}
  - 61: {fileID: 6100000}
  - 50: {fileID: 5000000}
  - 114: {fileID: 11400001}
  m_Layer: 14
  m_Name: CamelGreen
  m_TagString: Plane
  m_Icon: {fileID: 0}
  m_NavMeshLayer: 0
  m_StaticEditorFlags: 0
  m_IsActive: 1
--- !u!1 &100002
...

Throws the error:

JS-YAML: unknown tag !<tag:unity3d.com,2011:1> at line 22, column 1:
    --- !u!1 &100002
    ^

...\node_modules\js-yaml\lib\js-yaml\loader.js:154
    throw generateError(message);
          ^
YAMLException: JS-YAML: undeclared tag handle "!u!" at line 22, column 9:
    --- !u!1 &100002

But as far as my limited knowledge about Yaml goes, I do see a TAG declaration at the top of the Yaml file.

Then I tried to declare a custom tag:

var spaceYamlType = new yaml.Type('!u!', {
  loader: {
    kind: 'object',
    resolver: function (object) {
      return object;
    }
  },
  dumper: {
    kind: 'object',
    instanceOf: Object 
  }
});

var SPACE_SCHEMA = yaml.Schema.create([ spaceYamlType ]);

(Yes, that is code straight copied from the example) But that didn’t work either (same error).

Any idea what is going wrong here?

Arco

[divillysausages]

If anyone happens to come across this, this is the code that I’m using (in 2020/2021) to load prefab and script files:

const fs = require( 'fs' );
const yaml = require( 'js-yaml' );

module.exports = async function ( path ) {
    const types = {};

    let file = await fs.promises.readFile( path, 'utf8' );

    // remove the unity tag line
    file = file.replace( /%TAG.+\r?\n?/, '' );

    // replace each subsequent tag with the full line + map any types
    file = file.replace( /!u!([0-9]+).+/g, ( match, p1 ) => {

        // create our mapping for this type
        if ( !( p1 in types ) ) {
            const type = new yaml.Type( `tag:unity3d.com,2011:${p1}`, {
                kind: 'mapping',
                construct: function ( data ) {
                    return data || {}; // in case of empty node
                },
                instanceOf: Object
            } );
            types[p1] = type;
        }

        return `!<tag:unity3d.com,2011:${p1}>`
    } );

    // create our schema    
    const schema = yaml.Schema.create( Object.values( types ) );

    // parse our yaml
    const objAr = yaml.loadAll( file, null, { schema } );

    // objAr will be something like:
    // [
    //     {
    //         "GameObject": {
    //             ...
    //         }
    //     },
    //     {
    //         "Transform": {
    //             ...
    //         }
    //     },
    //     ...
    // ]
    return objAr;
}

You can just import that anywhere, something like (assuming a file named readUnityFile.js):

const readUnityFile = require('./readUnityFile');
readUnityFile( pathToUnityFile )

[dervus]

You must use loadAll function to load multi-document sources. See the README.