Cache Condition Directives

conditional

Wraps the inner route with support for conditional requests as defined by RFC 7232. Given the resource's EntityTag and/or Last-Modified date, the directive evaluates If-Match, If-Unmodified-Since, If-None-Match, If-Modified-Since and If-Range and answers 304 Not Modified or 412 Precondition Failed without running the inner route when the preconditions say so. The ETag and Last-Modified headers are added to every response except a 412, unless the inner route set them.

import org.http4s.{ EntityTag, HttpDate }

val tag = EntityTag("v42")
val modified = HttpDate.unsafeFromEpochSecond(1700000000L)

val route: Route = path("resource") {
  conditional(tag, modified) {
    complete("the resource")
  }
}

Three overloads exist: conditional(eTag), conditional(lastModified) and conditional(eTag: Option[EntityTag], lastModified: Option[HttpDate]). Entity tags are compared strongly for If-Match and If-Range and weakly for If-None-Match, as the RFC requires.