Merge branch 'Baeldung:master' into transparent-scala3

Author: yadavan88

build.sbt

@@ -326,7 +326,8 @@ lazy val scala_libraries_4 = (project in file("scala-libraries-4"))
     libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.2" % Test,
     libraryDependencies ++= Seq(
       "org.scala-lang.modules" %% "scala-async" % "1.0.1",
-      "org.scala-lang" % "scala-reflect" % scalaVersion.value % Provided
+      "org.scala-lang" % "scala-reflect" % scalaVersion.value % Provided,
+      "org.tpolecat" %% "skunk-core" % "0.3.2"
     ),
      libraryDependencies ++= Seq(
       "org.apache.spark" %% "spark-core" % sparkVersion,

scala-libraries-4/src/test/scala/com/baeldung/scala/skunk/Session.scala

@@ -0,0 +1,70 @@
+package com.baeldung.scala.skunk
+
+import cats.effect.{IO, IOApp}
+import cats.effect.kernel.Resource
+import skunk.{Query, Session}
+import cats.effect._
+import natchez.Trace.Implicits.noop
+import skunk._
+import skunk.implicits._
+import skunk.codec.all._
+
+object Skunk{
+  case class User(id: Int, username: String, email: String, age:Int)
+
+  def createSession(): Resource[IO, Session[IO]] =
+    Session.single[IO]( host = "localhost",
+      user = "baeldung",
+      database = "baeldung",
+      password = Some("baeldung"),
+      port = 5432
+    )
+
+  def getAllUsers(resource: Resource[IO, Session[IO]]) = {
+    val query: Query[Void, Int ~ String ~ String ~ Int] =
+      sql"SELECT * FROM Users"
+      .query(int4 ~ varchar(255) ~ varchar(255) ~ int4)
+
+    val mappedQuery: Query[Void, User] = query
+      .gmap[User]
+    val results: IO[List[User]] = resource.use(s => s.execute(mappedQuery))
+    results
+  }
+
+  def getUserWithId(resource: Resource[IO, Session[IO]]) = {
+    val query:Query[Int ~ String, User]  =
+      sql"""
+        SELECT * FROM Users WHERE
+          id = $int4 AND username LIKE $varchar
+       """
+      .query(int4 ~ varchar(255) ~ varchar(255) ~ int4)
+      .gmap[User]
+
+   val preparedQuery: Resource[IO, PreparedQuery[IO, Int ~ String, User]] =  resource
+      .flatMap(session => session.prepare(query))
+
+    preparedQuery.use(pq => pq.unique(1, "baeldungUser"))
+  }
+
+  def removeUserWithId(resource: Resource[IO, Session[IO]]) = {
+    val command: Command[Void]  =
+      sql"""
+        DELETE FROM Users WHERE
+          id = 5
+       """
+        .command
+
+    resource.use(session => session.execute(command))
+  }
+
+  def removePrepared(resource: Resource[IO, Session[IO]]) = {
+    val command: Command[Int ~ String]  =
+      sql"""
+        DELETE FROM Users WHERE
+          id = $int4 and username = $varchar
+       """
+        .command
+    resource.flatMap(session => session.prepare(command))
+      .use(pc => pc.execute((1, "baeldungUser")))
+  }
+}