xerial / sbt-sql

A sbt plugin for generating model classes from SQL files

GitHub

sbt-sql

A sbt plugin for generating model classes from SQL query files in src/main/sql.

Why you need sbt-sql?

  • Integrate the power of SQL and Scala
    • If you write an SQL, it creates a Scala class to read the SQL result.
  • Type safety
    • No longer need to write a code like ResultSet.getColumn("id") etc.
    • Editors such as IntelliJ can show the SQL result parameter names and types.
    • For example, if you rename a column name in SQL from id to ID, the code using id will be shown as compilation error. Without sbt-sql, it will be a run-time exception, such as Unknown column "id"!.
  • Reuse your SQL as a template
    • You can embed parameters in your SQL with automatically generated Scala functions.

Usage

Maven Central

sbt-sql supports only sbt 1.3.x or higher.

project/plugins.sbt

// For Presto
addSbtPlugin("org.xerial.sbt" % "sbt-sql-presto" % "(version)")

// For SQLite (available since 0.7.0)
addSbtPlugin("org.xerial.sbt" % "sbt-sql-sqlite" % "(version)")

// For Treasure Data Presto
addSbtPlugin("org.xerial.sbt" % "sbt-sql-td" % "(version)")

// For Generic JDBC drivers
addSbtPlugin("org.xerial.sbt" % "sbt-sql" % "(version)")
// Add your jdbc driver dependency for checking the result schema
libraryDependencies ++= Seq(
   // Add your jdbc driver here
)

build.sbt

This is an example of using a custom JDBC driver:

enablePlugins(SbtSQLJDBC)

// Add your JDBC driver to the dependency
// For using presto-jdbc
libraryDependencies ++= Seq(
  "org.wvlet.airframe" % "airframe-codec" % "20.6.2", // Necessary for mapping JDBC ResultSets to model classes
  "io.prestosql.presto" % "presto-jdbc" % "332"
 )

// You can change SQL file folder. The default is src/main/sql
// sqlDir := (sourceDirectory in Compile).value / "sql"

// Configure your JDBC driver
jdbcDriver := "io.prestosql.jdbc.PrestoDriver"
jdbcURL := "(jdbc url e.g., jdbc:presto://.... )"
jdbcUser := "(jdbc user name)"
jdbcPassword := "(jdbc password)"

sbt-sql-sqlite

sbt-sql-sqlite plugin uses src/main/sql/sqlite as the SQL file directory. Configure jdbcURL and jdbcUser properties:

enablePlugins(SbtSQLSQLite)

jdbcURL := "jdbc:sqlite:(sqlite db file path)"

sbt-sql-presto

sbt-sql-presto plugin uses src/main/sql/presto as the SQL file directory. Configure jdbcURL and jdbcUser properties:

enablePlugins(SbtSQLPresto)

jdbcURL := "jdbc:presto://api-presto.treasuredata.com:443/td-presto"
jdbcUser := "presto user name"

sbt-sql-td (Treasure Data Presto)

To use Treasure Data Presto, set TD_API_KEY environment variable. jdbcUser will be set to this value.

Alternatively you can set TD_API_KEY in your sbt credential:

$HOME/.sbt/1.0/td.sbt

credentials +=
  Credentials("Treasure Data", "api-presto.treasuredata.com", "(your TD API KEY)", "")
enablePlugins(SbtSQLTreasureData)

Writing SQL

src/main/sql/presto/sample/nasdaq.sql

@(start:Long, end:Long)
select * from sample_datasets.nasdaq
where time between ${start} and ${end}

From this SQL file, sbt-sql generates Scala model classes and several utility methods.

  • SQL file can contain template variables ${(Scala expression)}. To define user input variables, use @(name:type, ...). sbt-sql generates a function to populate them, such as Nasdaq.select(start = xxxxx, end = yyyyy). The variable can have a default value, e.g., @(x:String="hello").

Template Variable Examples

  • Embed a String value
@(symbol:String)
select * from sample_datasets.nasdaq
where symbol = '${symbol}'
  • Embed an input table name as a variable with the default value sample_datasets.nasdaq:
@(table:SQL="sample_datasets.nasdaq")
select * from ${table}

SQL type can be used for embedding an SQL expression as a String.

Import statement

You can use your own type for populating SQL templates by importing your class as follows:

@import your.own.class

Using Option[X] types

To generate case classes with Option[X] parameters, add __optional suffix to the target column names.

select a as a__optional // Option[X] will be used  
from ...
@optional(a, b)
select a, b, c // Option[A], Option[B], C 

Generated Files

target/src_managed/main/sample/nasdaq.scala

package sample

object nasdaq {
  def path : String = "/sample/nasdaq.sql"

  def sql(start:Long, end:Long) : String = {
    s""""select * from sample_dataest.nasdaq
where time between ${start} and ${end}
    """
  }

  def select(start:Long, end:Long)(implicit conn:java.sql.Connection): Seq[nasdaq] = ...
  def selectWith(sql:String)(implicit conn:java.sql.Connection): Seq[nasdaq] = ...
}

case class nasdaq(
  symbol: String,
  open: Double,
  volume: Long,
  high: Double,
  low: Double,
  close: Double,
  time: Long
)