All i need to execute a basic Jackson library code using scala in Intellij Idea editor
I already have installed scala
C:\Users\tt>scala -version
Scala code runner version 2.12.7 -- Copyright 2002-2018, LAMP/EPFL and Lightbend, Inc.
import com.fasterxml.jackson.databind.ObjectMapper
import scala.collection.mutable
val input = scala.io.Source.fromFile("data.json").getLines()
val mapper = new ObjectMapper() with ScalaObjectMapper
mapper.registerModule(DefaultScalaModule)
val obj = mapper.readValue[Map[String, Any]](input)
val data_collection = mutable.HashMap.empty[Int, String]
for (i <- c) {
data_collection.put(
obj.get("id").fold(0)(_.toString.toInt),
obj.get("text").fold("")(_.toString)
)
}
println(data_collection) // Map(1 -> Hello How are you)
I expect IntelliJ editor to automatcially suggest why ScalaObjectMapper and DefaultScalaModule showing as Cannot Resolve symbols despite of using correct imports
Getting errors like below
Error:(4, 1) expected class or object definition
name := "jackson-module-scala"
Error:(6, 1) expected class or object definition
organization := "com.fasterxml.jackson.module"
Error:(8, 1) expected class or object definition
scalaVersion := "2.12.8"
Error:(10, 1) expected class or object definition
crossScalaVersions := Seq("2.10.7", "2.11.12", "2.12.8",
"2.13.0-M5")
Error:(12, 1) expected class or object definition
val scalaMajorVersion = SettingKey[Int]("scalaMajorVersion")
Error:(13, 1) expected class or object definition
scalaMajorVersion := {
Error:(20, 1) expected class or object definition
scalacOptions ++= Seq("-deprecation", "-unchecked", "-feature")
Error:(27, 6) classes cannot be lazy
lazy val java7Home =
Error:(33, 1) expected class or object definition
javacOptions ++= {
Error:(41, 1) expected class or object definition
scalacOptions ++= {
Error:(45, 1) expected class or object definition
unmanagedSourceDirectories in Compile += {
Error:(49, 1) expected class or object definition
val jacksonVersion = "2.9.8"
Error:(51, 1) expected class or object definition
libraryDependencies ++= Seq(
Error:(65, 1) expected class or object definition
resourceGenerators in Compile += Def.task {
Error:(73, 1) expected class or object definition
site.settings
Error:(75, 1) expected class or object definition
site.includeScaladoc()
Error:(77, 1) expected class or object definition
ghpages.settings
Error:(79, 1) expected class or object definition
git.remoteRepo := "git#github.com:FasterXML/jackson-module-
scala.git"
Related
I've defined a case class to be used as a schema for a Dataset in Spark.
I want to be able to refer to individual columns from that schema by referencing them programmatically (vs. hardcoding their string value somewhere)
For example, for the following case class
final case class MySchema(id: Int, name: String, timestamp: Long)
I would like to auto-generate the following object
object MySchema {
val id = "id"
val name = "name"
val timestamp = "timestamp"
}
The Macro approach outlined here appears to be what I want, but it won't compile under Scala 2.12. It gives the following errors which are completely baffling to me and show up in a total of 2 Google results with 0 fixes.
[error] pattern var qq$macro$2 in method unapply is never used: use a wildcard `_` or suppress this warning with `qq$macro$2#_`
[error] case (c#q"$_ class $tpname[..$_] $_(...$params) extends { ..$_ } with ..$_ { $_ => ..$_ }") :: Nil =>
[error] ^
[error] pattern var qq$macro$19 in method unapply is never used: use a wildcard `_` or suppress this warning with `qq$macro$19#_`
[error] case (c#q"$_ class $_[..$_] $_(...$params) extends { ..$_ } with ..$_ { $_ => ..$_ }") ::
[error] ^
[error] pattern var qq$macro$27 in method unapply is never used: use a wildcard `_` or suppress this warning with `qq$macro$27#_`
[error] q"$mods object $tname extends { ..$earlydefns } with ..$parents { $self => ..$body }" :: Nil =>
[error] ^
Suppressing the warning as outlined won't work because the macro numbers change every time I compile.
It's also worth noting that the similar SO answer here runs into the same compiler errors as shown above
IntelliJ also complains about several parts of the macro that the compiler doesn't complain about, but that's not really an issue if I can get it to compile
Is there a way to fix that Macro approach to work in Scala 2.12 or is there a better Scala 2.12 way to do this? (I can't use Scala 2.13 or higher due to compute environment constraints)
Just checked that the macro is still working both in Scala 2.13.10 and 2.12.17.
Most probably, you didn't set up your project for macro annotations
build.sbt
//ThisBuild / scalaVersion := "2.13.10"
ThisBuild / scalaVersion := "2.12.17"
lazy val macroAnnotationSettings = Seq(
scalacOptions ++= (CrossVersion.partialVersion(scalaVersion.value) match {
case Some((2, v)) if v >= 13 => Seq("-Ymacro-annotations") // for Scala 2.13
case _ => Nil
}),
libraryDependencies ++= (CrossVersion.partialVersion(scalaVersion.value) match {
case Some((2, v)) if v <= 12 => // for Scala 2.12
Seq(compilerPlugin("org.scalamacros" % "paradise" % "2.1.1" cross CrossVersion.full))
case _ => Nil
})
)
lazy val core = project
.settings(
macroAnnotationSettings,
scalacOptions ++= Seq(
"-Ymacro-debug-lite", // optional, convenient to see how macros are expanded
),
)
.dependsOn(macros) // you must split your project into subprojects because macros must be compiled before core
lazy val macros = project
.settings(
macroAnnotationSettings,
libraryDependencies ++= Seq(
scalaOrganization.value % "scala-reflect" % scalaVersion.value, // necessary for macros
),
)
project structure:
core
src
main
scala
Main.scala
macros
src
main
scala
Macros.scala
Then just do sbt clean compile.
The whole project: https://gist.github.com/DmytroMitin/2d9dbd6441ebf167aa127b80fb516afd
sbt documentation:
https://www.scala-sbt.org/1.x/docs/Macro-Projects.html
Scala documentation: https://docs.scala-lang.org/overviews/macros/annotations.html
Examples of build.sbt:
https://github.com/typelevel/simulacrum/blob/master/build.sbt
https://github.com/DmytroMitin/AUXify/blob/master/build.sbt
I just set up a new scala project with sbt in IntelliJ, and wrote the following basic class:
Person.scala:
package learning.functional
case class Person(
name: String
)
Main.scala:
package learning.functional
import learning.functional.person
object Main{
val p = Person("John")
}
PersonTest.scala:
import learning.functional.Person
import org.scalatest.FunSuite
class PersonTest extends FunSuite {
test("test person") {
val p = Person("John")
assert(p.name == "John")
}
}
When I try to run sbt test, it throws the following error:
## Exception when compiling 1 sources to /Users/johndooley/Desktop/Scala/scala-learning/target/scala-2.13/test-classes
[error] java.lang.AssertionError: assertion failed:
[error] unexpected value engine in trait FunSuite final <expandedname> private[this]
[error] while compiling: /Users/johndooley/Desktop/Scala/scala-learning/src/test/scala/PersonTest.scala
What could be the reason for this? My build.sbt file:
ThisBuild / scalaVersion := "2.13.10"
libraryDependencies += "org.scalatest" % "scalatest_2.10" % "1.9.1"
lazy val root = (project in file("."))
.settings(
name := "scala-learning"
)
Project structure:
I have tried invalidating cache and restarting, doing clean, update, compile, but nothing works.
I solved this by modifying my dependency to the following:
libraryDependencies += "org.scalatest" %% "scalatest" % "3.2.14"
and completely reloading the sbt shell
I am trying to make my own custom CSV reader. I am using IntelliJ IDEA 14 with sbt and specs2 test framework.
The class I declared in src/main is as follows:
import java.io.FileInputStream
import scala.io.Source
class CSVStream(filePath:String) {
val csvStream = Source.fromInputStream(new FileInputStream(filePath)).getLines()
val headers = csvStream.next().split("\\,", -1)
}
The content of the test file in src/test is as follows:
import org.specs2.mutable._
object CSVStreamSpec {
val csvSourcePath = getClass.getResource("/csv_source.csv").getPath
}
class CSVStreamSpec extends Specification {
import CSVStreamLib.CSVStreamSpec._
"The CSV Stream reader" should {
"Extract the header" in {
val csvSource = CSVStream(csvSourcePath)
}
}
}
The build.sbt file contains the following:
name := "csvStreamLib"
version := "1.0"
scalaVersion := "2.11.4"
libraryDependencies ++= Seq("org.specs2" %% "specs2-core" % "2.4.15" % "test")
parallelExecution in Test := false
The error I am getting when I type test is as follows:
[error] /Users/raiyan/IdeaProjects/csvStreamLib/src/test/scala/csvStreamSpec.scala:18: not found: value CSVStream
[error] val csvSource = CSVStream(csvSourcePath)
[error] ^
[error] one error found
[error] (test:compile) Compilation failed
[error] Total time: 23 s, completed 30-Dec-2014 07:44:46
How do I make the CSVStream class accessible to the CSVStreamSpec class in the test file?
Update:
I tried it with sbt in the command line. The result is the same.
You forgot the new keyword. Without it, the compiler looks for the companion object named CSVStream, not the class. Since there is none, it complains. Add new and it'll work.
This was asked as a "bonus question" in https://stackoverflow.com/questions/12639454/make-scalacheck-tests-deterministic, but not answered:
Is there a way to print out the random seed used by ScalaCheck, so that you can reproduce a specific test run?
There is a hacky way: wrap a random generator to print its seed on initialization and pass it to Test.Parameters. Is there a better option?
As of today, this is possible (see scalacheck#263).
There are some nice examples here: Simple example of using seeds with ScalaCheck for deterministic property-based testing.
In short, you can do:
propertyWithSeed("your property", Some("seed")) =
forAll { ??? }
and the seed will be printed when this property fails.
There is no way to do this today. However, it will be implemented in the future, see https://github.com/rickynils/scalacheck/issues/67
This is my answer there:
Bonus question: Is there an official way to print out the random seed used by ScalaCheck, so that you can reproduce even a non-deterministic test run?
From specs2-scalacheck version 4.6.0 this is now a default behaviour:
Given the test file HelloSpec:
package example
import org.specs2.mutable.Specification
import org.specs2.ScalaCheck
class HelloSpec extends Specification with ScalaCheck {
package example
import org.specs2.mutable.Specification
import org.specs2.ScalaCheck
class HelloSpec extends Specification with ScalaCheck {
s2"""
a simple property $ex1
"""
def ex1 = prop((s: String) => s.reverse.reverse must_== "")
}
build.sbt config:
ThisBuild / scalaVersion := "2.13.0"
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.example"
ThisBuild / organizationName := "example"
lazy val root = (project in file("."))
.settings(
name := "specs2-scalacheck",
libraryDependencies ++= Seq(
"org.specs2" %% "specs2-core" % "4.6.0",
"org.specs2" %% "specs2-matcher-extra" % "4.6.0",
"org.specs2" %% "specs2-scalacheck" % "4.6.0"
).map(_ % "test")
)
When you run the test from the sbt console:
sbt:specs2-scalacheck> testOnly example.HelloSpec
You get the following output:
[info] HelloSpec
[error] x a simple property
[error] Falsified after 2 passed tests.
[error] > ARG_0: "\u0000"
[error] > ARG_0_ORIGINAL: "猹"
[error] The seed is X5CS2sVlnffezQs-bN84NFokhAfmWS4kAg8_gJ6VFIP=
[error]
[error] > '' != '' (HelloSpec.scala:11)
[info] Total for specification HelloSpec
To reproduce that specific run (i.e with the same seed), you can take the seed from the output and pass it using the command line scalacheck.seed:
sbt:specs2-scalacheck>testOnly example.HelloSpec -- scalacheck.seed X5CS2sVlnffezQs-bN84NFokhAfmWS4kAg8_gJ6VFIP=
And this produces the same output as before.
You can also set the seed programmatically using setSeed:
def ex1 = prop((s: String) => s.reverse.reverse must_== "").setSeed("X5CS2sVlnffezQs-bN84NFokhAfmWS4kAg8_gJ6VFIP=")
Yet another way to provide the Seed is pass an implicit Parameters where the seed is set:
package example
import org.specs2.mutable.Specification
import org.specs2.ScalaCheck
import org.scalacheck.rng.Seed
import org.specs2.scalacheck.Parameters
class HelloSpec extends Specification with ScalaCheck {
s2"""
a simple property $ex1
"""
implicit val params = Parameters(minTestsOk = 1000, seed = Seed.fromBase64("X5CS2sVlnffezQs-bN84NFokhAfmWS4kAg8_gJ6VFIP=").toOption)
def ex1 = prop((s: String) => s.reverse.reverse must_== "")
}
Here is the documentation about all those various ways.
This blog also talks about this.
I am trying to use LDAP via unboundid in scala but the compiler keeps crashing.
I just created an object that looks like this:
package utils
import com.unboundid.ldap.sdk._
object LdapHelper {
val ldap = LDAPConnection("ldap.example.com", 389)
}
I added this: "com.unboundid" % "unboundid-ldapsdk" % "2.3.1" to my appDependencies in Build.scala. I use Play 2.1 and Scala Version 2.10.1.
I get a very strange error message (see below):
The error message is so strange that i really dont know where to begin to look for hints.
Not sure if the problem is in unboundid, play, scala, sbt?
How can i successfully integrate unboundid in my scala project?
Thanks
Error in Scala compiler: assertion failed: while compiling: C:\play\todolist\app\utils\LdapHelper.scala during phase: global=typer, atPhase=parser library version: version 2.10.2 compiler version: version 2.10.2 reconstructed args: -classpath C:\play\todolist.target;C:\eclipse\scala-SDK-3.0.1-vfinal-2.10-win32.win32.x86_64\configuration\org.eclipse.
...
last tree to typer: Ident(LDAPConnection)
symbol: (flags: )
symbol definition:
symbol owners:
context owners: value ldap -> object LdapHelper -> package utils
== Enclosing template or block ==
Template( // val : in object LdapHelper
"java.lang.Object" // parents
ValDef(
private
"_"
)
// 3 statements
DefDef( // def : in object LdapHelper
""
[]
List(Nil)
Block(
Apply(
super.""
Nil
)
()
)
)
DefDef( // def x: in object LdapHelper
"x"
[]
Nil
()
)
ValDef( // private[this] val ldap: in object LdapHelper
private
"ldap"
Apply(
"LDAPConnection"
// 2 arguments
"ldap.example.com"
389
)
)
)
There was a warning that turned into an assert in Scala 2.10.2 causing this.
There is a bug open here:
https://issues.scala-lang.org/browse/SI-7014
And a fix staged for 2.10.4:
https://github.com/scala/scala/pull/2829
You can ask Play to use Scala 2.10.4-SNAPSHOT by using the following Build.scala:
import sbt._
import Keys._
import play.Project._
object ApplicationBuild extends Build {
val appName = "AppName"
val appVersion = "1.0-SNAPSHOT"
val mainDeps = Seq(
jdbc,
anorm,
cache
)
lazy val main = play.Project(appName, appVersion, mainDeps).settings(
scalaVersion := "2.10.4-SNAPSHOT"
)
}
If you are using build.sbt the file would look like:
import play.Project._
playScalaSettings
name := "AppName"
version := "1.0-SNAPSHOT"
scalaVersion := "2.10.4-SNAPSHOT"
libraryDependencies ++= Seq(jdbc, anorm, cache)
Note: if building from sbt (instead of play) you may have to add a repository resolver under the scalaVersion line such as:
resolvers += "Typesafe repository" at "http://repo.typesafe.com/typesafe/repo/"
The answer from #jeckhart works.
Firstly I use Scala 2.10.4-RC1 to build the Play 2.3 SNAPSHOT. Then use the output to compile with UnboundID.
Finally everything compiles with no assertion or error.
To build Play 2.3 SNAPSHOT using Scala 2.10.4-RC1, I modified the file framework/project/Build.scala.
Change these two section from
val buildScalaVersion = propOr("scala.version", "2.10.3")
val buildScalaVersionForSbt = propOr("play.sbt.scala.version", "2.10.3")
to
val buildScalaVersion = propOr("scala.version", "2.10.4-RC1")
val buildScalaVersionForSbt = propOr("play.sbt.scala.version", "2.10.4-RC1")