akka / akka/akka-http

formField fails if custom unmarshaller is in scope

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#541 7 comments 4 reactions 0 assignees View on GitHub

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1 - triaged help wanted t:docs
Dominant language
Scala
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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

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Research direction

The payload names no repository files or tests; start with the linked reproducer and trace the formField directive and FieldMagnet machinery while a generic unmarshaller is in scope. Done means formField works in that situation, or the limitation is documented with guidance for writing an unmarshaller.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
api, backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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