Send HTTP requests

Use Popcorn.Fetch when Elixir code needs HTTP in the browser. It uses the browser fetch() API. You can use it directly or through Req.

Using Req

Add Req to the application dependencies. We support Req 0.5 through 0.7 and 0.8.0-rc.0.

The adapter is compiled only when Req is available. If you add Req after Popcorn has already compiled, recompile it with mix deps.compile popcorn --force.

Popcorn installs its Req adapter when running in the browser. If you already customized the adapter, Popcorn won't install its own.

response = Req.get!("https://api.example.com/status")

You can also select the adapter for one request:

response =
  Req.get!(
    "https://api.example.com/status",
    adapter: Popcorn.Fetch.adapter()
  )

The adapter supports normal response bodies, :into functions, collectables, and :self streams. It buffers request bodies before upload.

Use Popcorn.Fetch directly

Use request/2 when the application does not depend on Req:

{:ok, response} =
  Popcorn.Fetch.request(%{
    method: "GET",
    url: "/api/status"
  })

IO.inspect(response.status)
IO.inspect(response.body)

An HTTP error status still returns {:ok, response}. Network failures and timeouts return {:error, reason}.

Browser limits

Cross-origin requests need permission from the target server's CORS policy. The browser controls cookies, redirects, restricted headers, and response decompression.

Popcorn cannot preserve compressed response bytes. It also cannot set headers such as Host or Cookie directly.