Unresolved dependency in published assembly package in SBT - sbt

Question

In my project there are 3 sub projects under root. build.sbt is as below.
proj_C depends on proj_A and proj_B.
If I created the assembly proj_C package with below command. It success and the assembly package could be imported in other projects.
sbt "project proj_C" assembly
If I publish with "sbt publish", as I defined addArtifact in proj_C settings, an assembly jar package is also generated and then published. But when I try to compile another project which imports this assembly jar, it will below error
[error] unresolved dependency: proj_A;1.0.0: not found
part of build.sbt is as below. Could anyone point me what I made wrong in my way?
Many thanks!
artifact in (Compile, assembly) := {
val art = (artifact in (Compile, assembly)).value
art.withClassifier(Some("assembly"))
}
lazy val assemblySettings = Seq(
assemblyMergeStrategy in assembly := {
{
case PathList("META-INF", xs # _*) => MergeStrategy.discard
case _ => MergeStrategy.first
}
}
)
lazy val root = Project(base = file("."))
.disablePlugins(sbtassembly.AssemblyPlugin)
.aggregate(proj_A, proj_B, proj_C)
.settings(
commonSettings,
skip in publish := true,
name := "proj_root"
)
lazy val proj_A= (project in file("proj_A"))
.disablePlugins(sbtassembly.AssemblyPlugin)
.settings(
commonSettings,
skip in publish := true,
name := "proj_A"
)
lazy val proj_B= (project in file("proj_B"))
.disablePlugins(sbtassembly.AssemblyPlugin)
.settings(
commonSettings,
skip in publish := true,
name := "proj_B"
)
lazy val proj_C= (project in file("proj_C"))
.settings(
commonSettings,
assemblySettings,
addArtifact(artifact in (Compile, assembly), assembly),
name := "proj_C"
) dependsOn(proj_A, proj_B)

Answer 1

First of all, I hope you know that the publishing of the fat jar is not recommended. And to be honest, in your case I really see no benefit in doing so.
If you simply publish A, B, C separately and then add the dependency in your other project it will all be automatically downloaded (along with dependencies of those projects). And the dependency management will be much easier...
But, since you want to add the A-assembly dependency, by the error I guess that you are actually adding the wrong jar. My guess would be that you publish both C.jar and C-assembly.jar, and you added the dependency like:
"your.organisation" %% "C" % "version"
but you should have:
"your.organisation" %% "C" % "version" classifier "assembly"