help: Handling parentheses in the path pattern not related prefixes

[whitlockjc]

I currently use path-to-regexp in Sway and a user reported an issue that I believe will require me to do a little escaping prior to calling path-to-regexp. The user is currently trying to create an OData path like /Users(:id) but a request path of /Users(1) does not match the regex where I would expect it to. Now, I realize the reason for this is that parentheses are special but before I just go blindly escaping/hacking this to work, I wanted to get your opinion on how best to handle this situation.

Note: OpenAPI/Swagger use bracket-based variable naming in paths so in the linked issue you'll see /Users({id}) instead of /Users(:id). Do not let this trip you up because I already handle converting OpenAPI/Swagger paths to Express-style paths. Also, OpenAPI/Swagger paths do not allow regex in their path pattern (in case that matters with suggesting a solution).

[blakeembrey]

Understood 😄 I actually wrote most of the RAML tooling for Node.js, so I'm also aware of this. Personally, I went and implemented my own path matcher and opened a PR to the Express.js router to make it extensible in 5.0. However, that's just an FYI since you asked for the best solution, and building a custom matcher would be best (but is not really available in Express.js today until, at least, router@2.0 is released). Would you be interested in using this approach? (I wouldn't mind spending some time exposing this work for you to re-use, I can also link to anything RAML-related which solved the same problems).

In terms of today, and if you want to continue mapping to current Express.js-compatible paths, you'll need to escape any special characters path-to-regexp has. Just be aware that although the current path-to-regexp is 1.x and has a lot of improved features, current Express.js uses 0.1.x and has a few quirks when it comes to matching.

[whitlockjc]

Is there a list of special characters? I am sure I can figure it out by code grokking but if you already know, or want to mention it for posterity.

[blakeembrey]

Sure. Of the top of my head, I believe it's (, ), :, *, + and ?.

Reference: https://github.com/pillarjs/path-to-regexp/blob/master/index.js#L27

[whitlockjc]

Thanks @blakeembrey. As for my being interested in you breaking out the reusable stuff from your RAML work, I'd love to help out. I'm all for helping the community.

[blakeembrey]

@whitlockjc Most of the work come from Osprey (https://github.com/mulesoft/osprey) which mostly involved a bit of refactoring of the router (pillarjs/router#29) to support custom path handlers, at which point I wrote https://github.com/mulesoft-labs/raml-path-match. I've been meaning to correct that router and release it separately so more people can actually use it, but the PR's been around for almost a year and a half now

/cc @dougwilson

[blakeembrey]

Closing this since the issue here was answered. You can escape path-to-regexp special characters with \\.