A Req plugin for sending multipart/form-data request bodies.

It builds on the multipart library: you assemble a Multipart struct and hand it to Req through the :multi option. The plugin then sets the Content-Type (with the multipart boundary) and Content-Length headers and streams the encoded body.

Usage

multipart =
  Multipart.new()
  |> Multipart.add_part(Multipart.Part.text_field("hello world", "greeting"))

Req.new()
|> ReqMulti.attach()
|> Req.post!(multi: multipart)

Building the multipart

The %Multipart{} struct comes from the multipart library. Start with Multipart.new/0 and add one part per field or attachment with Multipart.add_part/2, using a builder from Multipart.Part:

Multipart.new()
# a plain form field
|> Multipart.add_part(Multipart.Part.text_field("hello world", "greeting"))
# a file read from disk
|> Multipart.add_part(Multipart.Part.file_field("/path/to/photo.png", "photo"))
# a file whose bytes you already hold
|> Multipart.add_part(Multipart.Part.file_content_field("report.pdf", pdf, "document"))

Other common builders are Multipart.Part.stream_field/3 and the lower-level binary_body/2/file_body/2. See the Multipart.Part docs for the full list and their optional headers/opts arguments.

Options

• :multi - a %Multipart{} struct to encode and send as the request body. When set to any other value, the request raises an ArgumentError. When omitted, the request is sent unchanged.