NestedTransactions.md

Nested transactions details

Transaction blocks can be nested:

transaction {
    Actors.insert {
      it[firstName] = "Alice"
    }
    
    transaction {
        Actors.insert {
          it[firstName] = "Bruce"
        }
    }  // 1  
     
       // 2
     
    Actors.insert {
      it[firstName] = "Jeff"
    }
}      // 3 

In the happy flow:

• At point 1, nothing gets committed yet.
• At point 3, Alice, Bruce and Jeff are all committed.

For this to work correctly, the following configuration is required:

val db = Database.connect(...)
db.useNestedTransactions = true 

If db.useNestedTransactions is false then the code sample above would commit Alice and Bruce at point 1. Any following rollbacks() do not work. This appears to be a bug in the newest version: Jetbrains/Exposed/issues/605.