gleam-lang / fetch

📡 Make requests to HTTP servers with fetch

Fetch

Bindings to JavaScript's built in HTTP client, fetch.

If you are running your Gleam project on the Erlang target (the default for new Gleam projects) then you will want to use a different library which can run on Erlang, such as gleam_httpc.

import gleam/fetch
import gleam/http/request
import gleam/http/response
import gleam/javascript/promise

pub fn main() {
  let assert Ok(req) = request.to("https://example.com")

  // Send the HTTP request to the server
  use resp <- promise.try_await(fetch.send(req))
  use resp <- promise.try_await(fetch.read_text_body(resp))

  // We get a response record back
  resp.status
  // -> 200

  response.get_header(resp, "content-type")
  // -> Ok("text/html; charset=UTF-8")

  promise.resolve(Ok(Nil))
}

fetch's Issues

Passing options when sending fetch requests

Some time ago we chatted how we could make it possible to pass request options to fetch.send(). I actually forgot about the issue until I hopped back on my toy project this weekend and got stuck 😆 Opening a GH issue this time to keep it visible.

Here's the related discord discussion. We didn't reach any conclusion but it should help jog our memory.

The simplest solution would be to introduce a FetchOptions type that we would pass to a new dedicated function like fetch.send_with_options(request, options).

Another path would be having a new FetchRequest type that wraps the classic gleam/http/request.{Request} with additional fetch-specific fields, such as mode, credentials, etc. We could then provide a builder pipeline to take the request, add options, and send it.

Update for latest Gleam HTTP

Support for binary content

3rd party provides me with large gzip'ed json.

Add

@external(javascript, "../ffi.mjs", "read_body")
pub fn read_body(
  a: Response(FetchBody),
) -> Promise(Result(Response(BitArray), FetchError))

which the user must gunzip afterwards?

If so, I have a PR.

README example leads to errors

Hello, I am learning gleam and wanted to figure out how to make http calls in JS targets but the README example produces an error and I am not sure what to do.
Here are my steps:

1. $ gleam new fetch
2. $ cd fetch
3. $ gleam add gleam_fetch
4. copy and paste the code example from the current README
5. $ gleam run -t javascript

The result:

Compiled in 0.02s
    Running fetch.main
file:///Users/george/dev/gleam/fetch/build/dev/javascript/gleam_fetch/ffi.mjs:40
  let headers = new globalThis.Headers();
                ^

TypeError: globalThis.Headers is not a constructor
    at make_headers (file:///Users/george/dev/gleam/fetch/build/dev/javascript/gleam_fetch/ffi.mjs:40:17)
    at to_fetch_request (file:///Users/george/dev/gleam/fetch/build/dev/javascript/gleam_fetch/ffi.mjs:32:14)
    at Module.send (file:///Users/george/dev/gleam/fetch/build/dev/javascript/gleam_fetch/gleam/fetch.mjs:37:17)
    at main (file:///Users/george/dev/gleam/fetch/build/dev/javascript/fetch/fetch.mjs:21:12)
    at file:///Users/george/dev/gleam/fetch/build/dev/javascript/fetch/gleam.main.mjs:2:1
    at ModuleJob.run (node:internal/modules/esm/module_job:175:25)
    at async Loader.import (node:internal/modules/esm/loader:178:24)
    at async Object.loadESM (node:internal/process/esm_loader:68:5)