Bastion.Upload

lib/upload.march — Bastion.Upload: multipart form-data upload parsing.

Parses multipart/form-data request bodies into a list of UploadedFile records (for file fields) and a list of (name, value) pairs (for text fields).

The body is read fully into memory before parsing. This works well for uploads up to a few hundred MB on typical hardware; for true streaming to external storage see the Streaming section below.

── Usage ──────────────────────────────────────────────────────────────────────

fn handle_upload(conn) do
  let opts = { Bastion.Upload.default_opts() with
    max_file_size = 5_000_000,
    allowed_types = ["image/jpeg", "image/png", "image/webp"]
  }
  match Bastion.Upload.parse_conn(conn, opts) do
  Err(e) ->
    let msg = Bastion.Upload.error_message(e)
    Controller.json(conn, 422, "{\"error\":\"" ++ msg ++ "\"}")
  Ok(result) ->
    let files  = result.files
    let fields = result.fields
    let photo  = List.head(files)
    -- process files...
    Controller.json(conn, 200, "{\"uploaded\":" ++ String.from_int(List.length(files)) ++ "}")
  end
end

After the request handler returns, temporary files are automatically deleted via the after-send hook system.

Types

typeUploadedFileUploadedFile = {#

typeUploadOptsUploadOpts = {#

typeUploadResultUploadResult = {#

typeUploadErrorUploadError =#

Functions

fndefault_optsdefault_opts() : UploadOpts#

Return default upload options (10MB max file, 10 files, 64KB fields, all types allowed).

fnerror_messageerror_message(err : UploadError) : String#

Return a human-readable message for an UploadError.

fnparseparse(body : String, content_type : String, opts : UploadOpts) : Result(UploadResult, UploadError)#

Parse a raw multipart body with an explicit content-type header string.

Useful in tests where you build the body manually:

    let body = build_multipart_body(boundary, fields, files)
    let ct   = "multipart/form-data; boundary=" ++ boundary
    Bastion.Upload.parse(body, ct, Bastion.Upload.default_opts())

fnparse_connparse_conn(conn, opts : UploadOpts) : Result(UploadResult, UploadError)#

Parse a multipart/form-data request from a Conn.

Reads the full request body and content-type header, then delegates to parse/3.
Returns Ok(UploadResult) or Err(UploadError).