akka/akka-http

Marshaller.withFixedContentType doesn't seem to work

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#1,077 opened on May 2, 2017

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 (4 comments) (0 reactions) (0 assignees)Scala (1,311 stars) (598 forks)batch import
1 - triagedbughelp wantedt:docst:marshalling

Description

When I create a ToEntityMarshaller for a type with Marshaller.withFixedContentType, as so:

  case class SomeType2(content: String)

  implicit val st2AsCsv: ToEntityMarshaller[SomeType2] =
    Marshaller.withFixedContentType(ContentTypes.`text/csv(UTF-8)`)(_.content)

the response is still returning Content-Type: text/plain; charset=UTF-8. Using Marshaller.StringMarshaller.wrap works, though.

  case class SomeType1(content: String)

  implicit val st1AsCsv: ToEntityMarshaller[SomeType1] =
    Marshaller.StringMarshaller.wrap(MediaTypes.`text/csv`)(_.content)

Here's a minimal example to reproduce: https://gist.github.com/chadselph/9149bab77c7aebfcea24bc15c9b82495

I've only tested this on 10.0.5, am I doing something wrong or is this a bug?

Contributor guide

Tech stack
scala
Domain
backendapi
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Scala basicsAkka HTTP marshalling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the Marshaller.withFixedContentType method to understand why it does not correctly set the Content Type header. Compare its implementation with Marshaller.StringMarshaller.wrap, which works. Check the Akka HTTP source code (e.g., Marshaller.scala) and trace the marshalling logic for entities with fixed content types.