Guntis Smaukstelis
113 lines
3.9 KiB
Scala
113 lines
3.9 KiB
Scala
package db
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import cats.data.NonEmptyList
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import cats.effect._
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import cats.effect.unsafe.implicits.global
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import doobie._
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import doobie.implicits._
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import java.time.format.DateTimeFormatter
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import java.time.{LocalDateTime, ZoneId, ZonedDateTime}
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import doobie.postgres.implicits._
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case class SqlContent(value: String)
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object Postgres {
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def transactor[F[_]: Async]: Transactor[F] = Transactor.fromDriverManager[F](
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"org.postgresql.Driver",
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"jdbc:postgresql://localhost:5432/weather-tool",
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"postgres",
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"mysecretpassword"
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)
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def getResourceContent(path: String): IO[String] = {
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val streamResource = Resource.make(IO(getClass.getResourceAsStream(path))) { stream =>
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IO(stream.close()).handleErrorWith(_ => IO.unit)
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}
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streamResource.use { stream =>
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IO(scala.io.Source.fromInputStream(stream).mkString)
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}
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}
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// def findUserById(userId: Int)(implicit xa: Transactor[IO]): IO[Option[User]] = {
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// sql"SELECT id, name FROM users WHERE id = $userId"
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// .query[User]
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// .option
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// .transact(xa)
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// }
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def createWeatherTable(implicit xa: Transactor[IO]): IO[Int] = {
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for {
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createTableSql <- getResourceContent("/db/create_weather_table.sql")
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result <- Update0(createTableSql, None).run.transact(xa)
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} yield result
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}
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implicit val doubleOptionMeta: Meta[Option[Double]] = Meta[Double].imap(Option(_))(_.getOrElse(Double.NaN))
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def insertInWeatherTable(xa: Transactor[IO]): IO[Int] = {
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val formatter = DateTimeFormatter.ofPattern("yyyyMMdd_HHmm")
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val dateTime = LocalDateTime.parse("20230516_1500", formatter)
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val rigaZone = ZoneId.of("Europe/Riga")
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val zonedTime: ZonedDateTime = dateTime.atZone(rigaZone)
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// in pgAdmin run: ```SET TIMEZONE = 'Europe/Riga';```
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for {
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insertTableSql <- getResourceContent("/db/insert_weather_table.sql")
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result <- Update[(ZonedDateTime, String, Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], Option[Double], List[String])](
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insertTableSql
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).run((zonedTime, "Rīga", Some(20.2), Some(8.8), Some(15.6), None, None, None, None, None, None, None, None, None, None, List("hail", "rain"))).transact(xa)
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} yield result
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}
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def selectWeatherTable(xa: Transactor[IO]): IO[List[(String, Option[Double])]] = {
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val formatter = DateTimeFormatter.ofPattern("yyyyMMdd_HHmm")
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val rigaZone = ZoneId.of("Europe/Riga")
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val from = LocalDateTime.parse("20230516_0100", formatter).atZone(rigaZone)
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val to = LocalDateTime.parse("20230516_1500", formatter).atZone(rigaZone)
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val citiesNel = NonEmptyList.of("Rīga", "Rēzekne")
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val granularity = "HOUR" // "HOUR", "DAY", "MONTH", "YEAR"
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val columnName = "tempMin"
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val baseQuery =
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fr"""
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SELECT
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city,
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MIN(""" ++ Fragment.const(columnName) ++
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fr""") AS tempMin
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FROM weather
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WHERE
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""" ++ Fragments.in(fr"city", citiesNel) ++ fr"""
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AND dateTime BETWEEN $from AND $to
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AND """ ++ Fragment.const(columnName) ++fr""" IS NOT NULL
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GROUP BY city, EXTRACT(""" ++ Fragment.const(granularity) ++ fr""" FROM dateTime)
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"""
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baseQuery
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.query[(String, Option[Double])]
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.to[List]
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.transact(xa)
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}
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def dropWeatherTable(implicit xa: Transactor[IO]): IO[Int] = {
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for {
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dropTableSql <- getResourceContent("/db/drop_weather_table.sql")
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result <- Update0(dropTableSql, None).run.transact(xa)
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} yield result
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}
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def main(args: Array[String]): Unit = {
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val xa = transactor[IO]
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// val result = createWeatherTable(xa).unsafeRunSync()
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// val result = insertInWeatherTable(xa).unsafeRunSync()
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val result = selectWeatherTable(xa).unsafeRunSync()
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// val result = dropWeatherTable(xa).unsafeRunSync()
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println(s"result: $result")
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}
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}
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