Skip to content

Middleware

[Source]

A two-phase request processor that wraps handler execution.

Middleware is val — shareable across connections and stateless between requests.

before runs during the forward phase, before the handler. Use it for authentication, input validation, or request transformation. To short-circuit the chain (e.g., reject with 401), call ctx.respond() — the framework stops the forward phase and skips to after phases. The ? allows genuine errors to propagate; if before errors without responding, the framework sends 500. ctx.start_streaming() is also partial and errors if a response has already been sent. If before errors after a successful start_streaming(), the framework sends the terminal chunk to close the stream instead of sending 500.

after runs during the reverse phase, after the handler (or after any middleware that short-circuited). It always runs for every middleware whose before was invoked, regardless of whether the chain completed normally, short-circuited, or errored. Use it for logging, cleanup, or response modification. after is not partial — middleware authors handle errors internally if needed.

interface val Middleware

Public Functions

before

[Source]

fun box before(
  ctx: Context ref)
: None val ?

Parameters

Returns

after

[Source]

fun box after(
  ctx: Context ref)
: None val

Parameters

Returns