How should one configure Slick to persist tables between sessions? - database

Question

I have experienced some issues while setting up Slick 2.0.2. Any configuration that I do in one session is lost in the next. For example, in the first session, I create the table and add three people:
// H2 in-memory database
lazy val db = Database.forURL("jdbc:h2:mem:contacts", driver="org.h2.Driver")
// Contacts table
lazy val contacts = TableQuery[ContactsSchema]
// Initial session
db withSession { implicit session =>
contacts.ddl.create
// Inserts sample data
contacts += Person("John", "123 Main street", 29)
contacts += Person("Greg", "Neither here nor there", 40)
contacts += Person("Michael", "Continental U.S.", 34)
// Successfully retrieves data
contacts foreach { person =>
println(person)
}
}
All is well up to this point. The output repeats the three people whom I added. When I start a new session, I start to experience issues.
// New session in which the previous data is lost
db withSession { implicit session =>
contacts foreach { person =>
println(person)
}
}
The above block creates a org.h2.jdbc.JdbcSQLException: Table "CONTACTS" not found exception. If I edit as follows
db withSession { implicit session =>
contacts.ddl.create
contacts foreach { person =>
println(person)
}
}
then all the data is erased.
I see that the Scalatra guide to Slick uses a similar configuration to mine. What am I doing wrong? How should I get the data to persist between sessions? Does the fact that I am using an in-memory database have anything to do with it?

Answer 1

Two choices.
Either create a session and keep it open. That can be done with a withSession scope lower on the call stack or db.createSession.
Or add ;DB_CLOSE_DELAY=-1 to the database url. That keeps the db alive as long as the vm runs.
See http://www.h2database.com/html/features.html#in_memory_databases