feat: add URLParam function to router

[eduardoboucas]

I wanted to define a route like /route/{param} and extract the value of param in the handler. I didn't find a built-in way of extracting the value of URL parameters with the router, so this PR adds a function that wraps the URLParam function from chi.

Example usage:

r.Get("/jobs/{jobId}", func(w http.ResponseWriter, req *http.Request) error {
  jobId := r.URLParam(req, "jobId")
  
  doSomething(jobId)
  
  w.WriteHeader(http.StatusOK)

  return nil
})

Apologies if it's already possible to do this with the router and I completely missed it, in which case feel free to close the PR.

[mheffner]

Cool 👍

[mraerino]

i don't get why this needs to be a method on the chiWrapper?
why not make this a freestanding function?

[eduardoboucas]

It doesn't have to be, as it doesn't access the chi instance, but from a functional perspective it felt like the appropriate place. I don't have a strong preference, though. What location do you suggest? router/helpers.go?

[mraerino]

i feel like it could just be some code like this to reexport it?

const URLParam = chi.URLParam

[eduardoboucas]

I personally prefer having a method that we explicitly implement and which we can customise the behaviour of in the future, if needed.

Is this a blocker for you?

[mraerino]

you can replace a reexport with a freestanding function at any point, it will not break anyone except if the signature differs which is the same if it is a function now.

[mraerino]

i've often just used chi.URLParam directly

[eduardoboucas]

i've often just used chi.URLParam directly

But that means using chi as a direct dependency and interacting both with the abstraction and with the underlying package, which doesn't feel ideal?

[mheffner]

Good to merge?

[eduardoboucas]

Good to merge?

Ouch, sorry! This one fell through the cracks.

Unless #259 (comment) is a blocker, this is good to go. I'll wait for that to be clarified and then merge.