Edda.Json

JSON request/response helpers for Edda.

Built on top of saga_json. The ToJson / FromJson traits do the work; this module is just the glue between them and Edda's Request / Response.

Types

BodyError

type BodyError =
  | NoBody
  | NotUtf8
  | JsonError J.Error

Why decoding a JSON body failed. Keeps body-level problems (missing body, non-UTF8) distinct from JSON-level ones (malformed, wrong shape) so the response can say something useful.

Functions

json

fun json : Int -> a -> Response where {a: ToJson}

Encode a value as a JSON response body with the given status. Sets Content-Type: application/json automatically.

body_json

fun body_json : Request -> Result a BodyError where {a: FromJson}

Decode the request body as JSON into a value of type a.

The call site needs a type annotation to pick the right FromJson impl: body_json req : Result User BodyError

body_error_response

fun body_error_response : BodyError -> Response

A reasonable default 400 response for BodyError. Most apps will want this directly; apps with structured error envelopes can write their own mapping.