Stringify list items with custom tags

[smith-xyz]

I'm trying to work with some yaml that has ruby object tags, specifically the !ruby/object:SomeRule tag for each list item. I'd like to use the custom api tag but I'm struggling to determine how to take the value that is matching and returning what is needed in the stringify method.

import YAML, { ScalarTag } from 'yaml'
import { stringifyString } from 'yaml/util'

const original = `--- 
:some_rules: !seq:SomeRules 
  - !ruby/object:SomeRule 
    id: 1
  - !ruby/object:SomeRule 
  id: 2
  - !ruby/object:SomeRule 
  id: 3
`;

// @ts-ignore
const someRuleRubyTag = {
  identify: value => typeof value === "object" && Object.keys(value!).includes("id"),
  tag: '!ruby/object:SomeRule',
  stringify(item, ctx, onComment, onChompKeep) {
// not sure how to handle the match that arrives here
    return stringifyString(item, ctx, onComment, onChompKeep)
  }
} as ScalarTag;

const jsobj = { ":some_rules": [ { "id": 1 }, { "id": 2 }, { "id": 3 } ]};

console.log(YAML.stringify(
  jsobj,
  { customTags: [someRuleRubyTag] }
));

It seems possible as I get that custom tag back which is great but the value for that tag I can't seem to get (the list item).

[eemeli]

The tag method that you're missing isn't actually stringify, but createNode. Tags that extend maps and sequences require you to define how to turn e.g. something like a !ruby/object:SomeRule into a YAML map. Once you've done that, you should not need to customise the stringifier at all.

[smith-xyz]

Thank you so much, that brought it into perspective! For this particular case, I ended up doing something like this (super rough matching but just for anyone who stumbles on this) since the object key also needed a special tag:

const someRulesRubyTag: ScalarTag = {
  identify: (value) => {
    return Array.isArray(value);
  },
  createNode: (schema, value) => {
    const seq = new YAMLSeq(schema);
    if (Array.isArray(value)) {
      value.forEach(item => {
        const map = new YAMLMap(schema);
        if (item && typeof item === "object") {
          (Object.keys(item) as Array<keyof typeof item>).forEach((key) => {
            map.add(new Pair(key, item[key]));
          });
        }
        map.tag = "!ruby/object:SomeRule"
        seq.add(map);
      })
    }
    seq.tag = "!seq:SomeRules";
    return seq
  },
  tag: "!seq:SomeRules",
  resolve: (value) => value,
  default: false,
};

const jsobj: any = { ":some_rules": [ { "id": 1, "description": "test" }, { "id": 2,  "description": "test"}, { "id": 3,  "description": "test" } ]};

console.log(YAML.stringify(
  jsobj,
  { customTags: [someRulesRubyTag] }
));

/**
:some_rules:
  !seq:SomeRules
  - !ruby/object:SomeRule
    id: 1
    description: test
  - !ruby/object:SomeRule
    id: 2
    description: test
  - !ruby/object:SomeRule
    id: 3
    description: test
*/