Either warn or allow for IDs to contain `:` characters

[lencioni]

I was recently building a toy project with Relay and GraphQL where I needed to encode extra information in my global ID. To do this, I decided to add an idFetcher argument to my globalIdField call that returned a string that was delimited by a :. However, this did not work because of how globalIds are deconstructed in fromGlobalId, so instead of getting my encoded ID (e.g. 123:test) I just got the ID part (e.g. 123).

To prevent this confusion, it might be nice to either warn when this happens or use a different strategy in fromGlobalId than split. Here's a performant version that satisfies this use-case:

export function fromGlobalId(globalId: string): ResolvedGlobalId {
  var unbasedGlobalId = unbase64(globalId);
  var delimiterPos = unbasedGlobalId.indexOf(':');
  return {
    type: unbasedGlobalId.substring(0, delimiterPos),
    id: unbasedGlobalId.substring(delimiterPos + 1)
  };
}

Of course, you could also use a regex if you prefer (but I think I like the substring solution):

export function fromGlobalId(globalId: string): ResolvedGlobalId {
  var tokens = unbase64(globalId).match(/(.+?):(.+)/);
  return {
    type: tokens[1],
    id: tokens[2]
  };
}

Let me know what you think. I'll probably just submit a PR for this change for your convenience.

[dschafer]

Thanks for the report and patch!