Reafactor/2024 12 schema project replacement

[takapi327]

Implementation Details

This modification changes the way Table types are constructed using the Schema project.
Below we will look at the construction of the Table type corresponding to the User model.

case class User(
  id: Long,
  name: String,
  age: Option[Int],
)

Before

Until now, we had to create instances of Table directly; the arguments of Table had to be passed the corresponding columns in the same order as the properties possessed by the User class, and the data type of the columns had to be set as well, which was mandatory.

The TableQuery using this table type was implemented using Dynamic, which allows type-safe access, but the development tools could not do the completion.

This method of construction was also a bit slower in compile time than class generation

val userTable = Table[User]("user")(
  column("id", BIGINT, AUTO_INCREMENT, PRIMARY_KEY),
  column("name", VARCHAR(255)),
  column("age", INT.UNSIGNED.DEFAULT(None)),
)    

After

In this modification, Table type generation has been changed to a method of creating a class by extending Table. In addition, the data type of a column is no longer required, but can be set arbitrarily by the implementer.

This change to a construction method similar to that of Slick has made it more familiar to implementers.

class UserTable extends Table[User]("user"):
  def id: Column[Long] = column[Long]("id")
  def name: Column[String] = column[String]("name")
  def age: Column[Option[Int]] = column[Option[Int]]("age")

  override def * : Column[User] = (id *: name *: age).to[User]

The data type of the columns can still be set. This setting is used, for example, when generating a schema using this table class.

class UserTable extends Table[User]("user"):
  def id: Column[Long] = column[Long]("id", BIGINT, AUTO_INCREMENT, PRIMARY_KEY)
  def name: Column[String] = column[String]("name", VARCHAR(255))
  def age: Column[Option[Int]] = column[Option[Int]]("age", INT.UNSIGNED.DEFAULT(None))

  override def * : Column[User] = (id *: name *: age).to[User]

Pull Request Checklist

• Wrote unit and integration tests
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code formatting by scalafmt (sbt scalafmtAll command execution)
• Add copyright headers to new files

References