Scala Play集成ReactiveMongo失败：依赖未找到问题求助

Hey there, let's work through why you're hitting that frustrating unresolved dependency error. The core issue here is a version mismatch between Scala, Play Framework, and ReactiveMongo—let's break it down and fix it step by step.

Why This Error Happens #

The dependency you're trying to use:

org.reactivemongo#play2-reactivemongo_2.12;0.11.7.play24

doesn't exist in any public repository, and here's the breakdown:

• The 0.11.7.play24 suffix tells us this ReactiveMongo version is built exclusively for Play 2.4.
• Play 2.4 only supports Scala 2.10 and 2.11—there's no official build of Play 2.4 that works with Scala 2.12.
• So combining Scala 2.12 with Play 2.4 + ReactiveMongo 0.11.7 is an incompatible mix that simply doesn't exist.

Solutions to Fix the Error #

Option 1: Stick with Play 2.4 (Downgrade Scala) #

If you want to keep using Play 2.4, you'll need to switch your project to Scala 2.11.x (the latest stable release is 2.11.12):

1. Update your build.sbt to set the correct Scala version:

   scalaVersion := "2.11.12"
   

2. Adjust your ReactiveMongo dependency to match (using %% lets sbt auto-apply the Scala version suffix):

   libraryDependencies += "org.reactivemongo" %% "play2-reactivemongo" % "0.11.7.play24"
   

Option 2: Keep Scala 2.12 (Upgrade Play Framework) #

If you want to stay on Scala 2.12, you need to upgrade Play to a version that supports it. Play 2.5+ works with Scala 2.12, but we recommend a newer, supported release like Play 2.6, 2.7, or 2.8. Here's how to match ReactiveMongo versions:

• Play 2.6 → ReactiveMongo 0.12.7.play26
• Play 2.7 → ReactiveMongo 0.18.1.play27
• Play 2.8 → ReactiveMongo 1.0.10.play28

For example, if you upgrade to Play 2.8, your dependency would look like this:

libraryDependencies += "org.reactivemongo" %% "play2-reactivemongo" % "1.0.10.play28"

Quick Check: Verify Your Resolvers #

Make sure your build.sbt includes the ReactiveMongo releases repository—this ensures sbt can locate the dependency:

resolvers += "ReactiveMongo Releases" at "https://releases.reactivemongo.org/releases"

Final Note #

Always double-check that your Scala, Play, and ReactiveMongo versions align. ReactiveMongo's version naming follows a strict pattern: [reactivemongo-version].play[play-version], so you can easily match them up for compatibility.

内容的提问来源于stack exchange，提问作者Jwan622