akka/akka-http

empty Uri fragment ignored

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#3,859 opened on Jun 29, 2021

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Description

The Uri.withFragment function does not allow one to set an empty fragment, which is allowed by the IETF spec I believe, and by the Uri constructor, as shown:

import akka.http.scaladsl.model.Uri
import Uri.*

scala> val good = Uri("https",Authority(Host("example.com")),Path./("doc"),None,Some(""))       
val good: akka.http.scaladsl.model.Uri = https://example.com/doc#

scala> val noFrag = Uri("https",Authority(Host("example.com")),Path./("doc"),None,None)
val noFrag: akka.http.scaladsl.model.Uri = https://example.com/doc

scala> noFrag.withFragment("")
val res3: akka.http.scaladsl.model.Uri = https://example.com/doc

Contributor guide

Tech stack
None
Domain
backend
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.
1-3 hours
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.
clear
Prerequisites
Scala basicsURI RFC knowledgeAkka HTTP source structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
The issue is in the `withFragment` method of `Uri` class in Akka HTTP. The current implementation treats an empty string as no fragment, but the URI constructor allows empty fragment. To fix, examine `Uri.scala` around the `withFragment` method (likely in `akka http core/src/main/scala/akka/http/scaladsl/model/Uri.scala`). The fix should ensure that setting an empty fragment string results in a URI with an empty fragment, not `None`. Check the constructor logic for how fragment is stored and adapt `withFragment` accordingly. Also review the IETF URI spec (RFC 3986) to confirm empty fragment is allowed.