Scala: Guide for Data Science Professionals

Accessing database metadata

Commonly, especially during development, you might start the script by dropping the table if it exists, then recreating it. We can find if a table is defined by accessing the database metadata through the MTable object. To get a list of tables with name matching a certain pattern, we can run MTable.getTables(pattern):

scala> import slick.jdbc.meta.MTable
import slick.jdbc.meta.MTable

scala> db.withSession { implicit session =>
  MTable.getTables("transactions").list
}
List[scala.slick.jdbc.meta.MTable] = List(MTable(MQName(fec.transactions),TABLE,,None,None,None) ...)

Thus, to drop the transactions table if it exists, we can run the following:

scala> db.withSession { implicit session =>
 if(MTable.getTables("transactions").list.nonEmpty) ...