Resolve aliases when using getIn

[remcohaszing]

Is your feature request related to a problem? Please describe.

I have a situation where I have a list of paths from a YAML document. I need to map these paths to the location in the document source code. This can be done using the following code:

import { parseDocument } from 'yaml';

const yaml = `
foo: &anchor
  bar: 1
fooz:
  baz: *anchor
`;

const doc = parseDocument(yaml, {});
console.dir(doc.getIn(['foo', 'bar'], true));
console.dir(doc.getIn(['fooz', 'baz'], true));
console.dir(doc.getIn(['fooz', 'baz', 'bar'], true));

Unfortunately the last statement doesn’t work, because getIn doesn’t resolve aliases.

Describe the solution you'd like

I would love for getIn to be able to resolve aliases.

Describe alternatives you've considered

Possibly new methods can be introduced: resolve(key, keepScalar?) and resolveIn(path, keepScalar?). This would avoid breaking changes in get and getIn respectively.

It’s possible to do this manually, but I think it’s a useful feature for this library to support out of the box.

Additional context

We use this together with the jsonschema package. Apart from this issue, it’s working amazing!

[eemeli]

I like this idea. I'd really rather not add any new methods specifically for it, though.

I'm rather tempted to say that going from doc.getIn(['fooz', 'baz', 'bar'], true) returning undefined to indicate not finding the value, to it returning the Scalar { value: 1 } should not count as a breaking change: Really it's just an improvement in the search method.

Or is there a potential real-world use where this might break something?

[remcohaszing]

I think whether or not this is a breaking change really depends on how you look at it. For me this wouldn’t break anything, nor can I think of any potential real-world use cases that could break, but it is a change of behaviour.

Another alternative would be to accept an options object:

interface GetOptions {
  keepScalar?: boolean;
  resolveAnchors?: boolean;
}

doc.getIn(path: Iterable<unknown>, options?: boolean | GetOptions)

Passing true would be equivalent to { keepScalar: true }

---

I think it also makes sense to resolve the alias node itself if that would be the result. So given the example above, the following two lines would be equivalent:

console.dir(doc.getIn(['foo'], true));
console.dir(doc.getIn(['fooz', 'baz'], true));

[remcohaszing]

I’ll gladly provide a pull request if we reach concensus about the options format. :)