(feat): Add request.set_headers and request.prepend_headers

[dmmulroy]

This PR adds pluralized versions for set_header and prepend_header that will each take a list of #(String, String) and apply them to the request in the same fashion as the singular versions. In addition, tests have been added to cover the new functions.

[lpil]

Thank you for this, but seeing as one can pipe the existing function I don't yet know of a strong case for their additions.

What was the situation which prompted you to implement these?

[dmmulroy]

I like constructing headers in their own function, generally, into a list and adding them to requests as such. Here's an example

fn to_http_request(
  client: Client,
  method: Method,
  req: Request,
) -> HttpRequest(String) {
  let headers =
    client
    |> headers
    |> merge_headers(req.headers)

  let body =
    req.body
    |> option.map(json.to_string)
    |> option.unwrap("")

  let query =
    option.map(req.query, fn(params) {
      list.map(params, fn(param) {
        let key = pair.first(param)
        let value = pair.second(param)

        #(uri.percent_encode(key), uri.percent_encode(value))
      })
    })
    |> option.unwrap([])

  request.new()
  |> request.set_method(method)
  |> request_ext.set_headers(headers)
  |> request.set_scheme(Https)
  |> request.set_host(host)
  |> request.set_body(body)
  |> request.set_path(req.path)
  |> request.set_query(query)
}

Full code: https://github.com/dmmulroy/glitch/blob/main/src/glitch/api/client.gleam#L97

[dmmulroy]

I'd also add there is kind of a precedence for this type of API in the library already with set_query which takes a list of query params rather than adding one at a time.

pub fn set_query(
  req: Request(a),
  query: List(#(String, String)),
) -> Request(a)

[lpil]

In this specific case I think it'd be best to use the Gleam HTTP request type rather than having a custom one

[dmmulroy]

I don't think I'm fully following what you're suggesting here - could you clarify?

I concur that I definitely don't need the extra Request and the HttpRequest alias type. I'l probably get rid those tomorrow and just use the gleam_http Request. That being said, I don't want to expose the Request type to users so at some point I need to translate input data to headers. My choices currently are:

1. Repeatedly calling request.set_header, but this isn't great because the number of headers I may add is dynamic so its clashes with using a single chain of functions via the pipe operator.

2. Do something like this where I map input data to a gleam_http Request

  Request(..request.new(), headers: headers)
  |> request.set_method(method)
  |> request.set_scheme(Https)
  |> request.set_host(host)
  |> request.set_body(body)
  |> request.set_path(req.path)
  |> request.set_query(query)

3. Use an "extension module" like request_ext.set_headers

[lpil]

Let's keep this being something in your codebase for now, and we can see if it's something that there's a demand for later. Time often brings more clarity.

[dmmulroy]

Sounds good - thanks for engaging and thanks for your time, always appreciate it.

[lpil]

No, thank you!! Contributions are super important

[dmmulroy]

Okay I'm back, and I feel more strongly now that this should be added.

I just ran into a really confusing "bug" where I had a http request (using httpc) fail because gleam_http did not properly lowercase my headers and when httpc invoked this expression¹:

|> request.get_header("content-type")

It does not find the header because I add my headers dynamically and as a list. Right now, the obvious way to do this, as we discussed above, is to supply the header list to the constructor like this²:

Request(..request.new(), method: Get, headers: headers)

Since using a "builder" pattern is fairly idiomatic in Gleam, and appears to be the preferred api with gleam_http along with request.new(). I think we should really consider adding set_headers so that other users can easily add a list of headers via the build pattern/api and have gleam_http take care of the lowercasing for them

I am also opening a second PR³ that I think is more important than this one to make get_header case_insensitive during the search, but I still think we should make it as easy as possibly to do the right thing.

Footnotes

1. https://github.com/gleam-lang/httpc/blob/v2.1.2/src/gleam/httpc.gleam#L80 ↩

2. https://github.com/dmmulroy/glitch/blob/a508cb1b915934b004d64dae8bdc31fe05064a1b/src/glitch/api/client.gleam#L56-L68 ↩

3. https://github.com/gleam-lang/http/pull/54 ↩

[dmmulroy]

See #54 for additional context on why this was closed