Requests

Read headers, body, query strings, and form data from the incoming request.

Method and path

code

let method = toucan.method_of(c)   // "GET", "POST", ...
let path   = toucan.path_of(c)     // "/users/42"
let query  = toucan.query_of(c)    // "page=2&sort=asc"

Headers

Read a specific header by name (case-insensitive):

code

let auth   = toucan.header_of(c, "Authorization")
let cookie = toucan.header_of(c, "Cookie")
let ct     = toucan.content_type_of(c)

Returns "" when the header is absent.

Request body

code

let body = toucan.body_of(c)

The raw body string. For JSON APIs, parse this directly. For forms, use form_field instead.

Query parameters

Parse the query string into key-value pairs:

code

let params = toucan.query_params(c)           // List(#(String, String))
let page   = toucan.query_param(c, "page")    // "2" or ""
let sort   = toucan.query_param(c, "sort")    // "asc" or ""

Form data

Parse application/x-www-form-urlencoded request bodies:

code

fn handle_signup(c: toucan.Ctx) -> toucan.Ctx:
  let name  = toucan.form_field(c, "name")
  let email = toucan.form_field(c, "email")
  case string.is_empty(name):
    True  -> toucan.redirect(c, "/signup?error=missing_name")
    False -> create_user_and_redirect(c, name, email)

form_field returns "" when the field is absent or the body is not form-encoded.

For large multipart uploads, prefer a focused parser in your app or a package designed for binary uploads. The file_upload example shows the current shape: small text uploads can be parsed in Donna, while image uploads use a small FFI helper so files are written as real binary data.

URL parameters

Parameters captured from :name segments in toucan.path:

code

fn show_user(c: toucan.Ctx) -> toucan.Ctx:
  c
  |> toucan.get
  |> toucan.path("/users/:id")
  |> render_user

fn render_user(c: toucan.Ctx) -> toucan.Ctx:
  let id = toucan.param(c, "id")
  toucan.json(c, "{\"id\":\"" <> id <> "\"}")

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