Option to ignore unresolved aliases

[rarkins]

We have a use case in Renovate Bot where users would like Renovate to ignore unresolved aliases and continue anyway: renovatebot/renovate#31902

Is there any technical or philosophical reason why this option couldn't be supported?

[eemeli]

If you need special handling for unresolved aliases, why not define a visitor to apply it? For an example, see #497 (comment).

[rarkins]

Thanks for the quick response. Do you mean something like this?

import { parseDocument, visit } from 'yaml'

const doc = parseDocument('foo: *bar');
visit(doc, {
  Alias(key, node) {
    if (!node.resolve(doc)) return undefined
  }
});

Would you expect that to fix/remove any doc.errors? I attempted it with this code but it didn't work:

  const rawDocuments = parseAllDocuments(
    massagedContent,
    prepareParseOption(options),
  );

  const schema = options?.customSchema;

  const results: ResT[] = [];
  for (const rawDocument of rawDocuments) {
    visit(rawDocument, {
      Alias(key, node) {
        if (!node.resolve(rawDocument)) {
          return undefined;
        }
      },
    });

    const document = rawDocument.toJS({ maxAliasCount: 10000 });

    const errors = rawDocument.errors;
    // handle YAML parse errors
    if (errors?.length) {
      const error = new AggregateError(errors, 'Failed to parse YAML file');
      if (options?.failureBehaviour === 'filter') {
        logger.debug({ error, document }, 'Failed to parse YAML');
        continue;
      }
      throw error;
    }

[eemeli]

I meant applying some change to the node or document in the visitor. As is, returning undefined does nothing. If you want to replace the node, create its replacement and return that. See the docs here: https://eemeli.org/yaml/#finding-and-modifying-nodes

[rarkins]

If done correctly, will modifying nodes automatically resolve associated errors?

[eemeli]

Within this library, yes, because alias resolution is only done when calling toJS(), but in your larger application context I've no idea what errors you might end up experiencing because of these unresolved aliases.