Add not found schema to base services

[paulmelnikow]

This code is from the clojar badge:

    if (Object.keys(json).length === 0) {
      /* Note the 'not found' response from clojars is:
          status code = 200, body = {} */
      throw new NotFound()
    }

We have a bunch of other similar examples, where the schema is written to accommodate the not found case, and then there's code written to detect the alternate case and throw an error.

This responsibility is a kind of schema validation. We'd have clearer guarantees, particularly in the "found" case, if this responsiblity were delegated to Joi.

A really clean way to express this would be to optionally provide two schemas to _requestJson and friends. One would be the schema for the success case (like what we're passing now) and the other a notFoundSchema. If the notFoundSchema matches, we automatically throw NotFound, using the 404 error message.

[calebcartwright]

Something I've seen (which I think is along the very same lines), is that for not found scenarios some services will return an HTTP 200 with an html page (that contains the text '404 Not Found'). Would it be feasible to have a notFoundSchema that can handle those html scenarios too?

[paulmelnikow]

some services will return an HTTP 200 with an html page (that contains the text '404 Not Found')

😝

Are these JSON services? notFoundSchema would require valid JSON, though we could have a notFoundRegex which we test if the JSON won't parse, before returning the typical "unparseable json".

[calebcartwright]

Two places where I've seen this recently are:

• Snyk (for npm package) https://github.com/badges/shields/blob/master/services/snyk/snyk-vulnerability-npm.service.js#L52
• Coverity (https://github.com/badges/shields/blob/master/services/coverity/coverity-scan.service.js#L73)

Are these JSON services?

😆 They'll return JSON if the query target exists, but doing that HTML nonsense otherwise. I believe the current behavior with those would be invalid response for the badge message when the projects are not found since that HTML isn't valid JSON

[paulmelnikow]

I believe the current behavior with those would be invalid response for the badge message when the projects are not found since that HTML isn't valid JSON

It'd be nice to improve on that.

[calebcartwright]

Actually I'm wrong 🤦‍♂️ Forgot I added this to return a more meaningful message.

Still would be great if those services would actually respond with a 404 status code or always return JSON so we could use the notFoundSchema approach