akka/akka-http

formField fails if custom unmarshaller is in scope

Open

#541 opened on Nov 17, 2016

View on GitHub
 (7 comments) (4 reactions) (0 assignees)Scala (598 forks)batch import
1 - triagedhelp wantedt:docs

Repository metrics

Stars
 (1,311 stars)
PR merge metrics
 (Avg merge 1d 10h) (2 merged PRs in 30d)

Description

formField directive fails if there is too generic unmarshaller in scope, that prevents FieldMagnet machinery to work. It can happen quite a lot - for example when using akka-http-json4s or other generic unmarshaller.

Reproducer https://github.com/marekzebrowski/akka-http-form-field-bug

If it is not solvable, maybe a word of warning in documentation, or a guide how to write own unmarshaller would be helpful

Contributor guide

Research direction
Investigate how formField selects implicit unmarshaller and why a generic one causes failure. Look into implicit resolution and FieldMagnet priority. Consider adding a more specific unmarshaller or using a different approach.
Tech stack
scala
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
ScalaAkka HTTP
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50