Adding comments into Slick

Question

Is there a way I can add comments into the sql that is formed by slick without writing a raw sql statement? This is to keep track of the code in application that launched the sql.

Something similar to this https://www.techonthenet.com/postgresql/comments.php — binshi, Dec 05 '18 at 16:31

score 3 · Answer 1 · answered Jul 21 '19 at 23:12

I'm sorry to say no. Currently in the 3.3.1 version of Slick, there is no way to add a comment to queries other that creating the SQL code by hand.

It may be get added later as there is an open issue years ago for that:

https://github.com/slick/slick/issues/468

score 0 · Answer 2 · answered Jan 05 '23 at 21:41

We accomplished this by downcasting DBIOAction and using SqlAction.overrideStatements:

val databaseAction: DBIOAction[A, NoStream, E] = ??? // your action 
val comment: String = ??? // your comment
val annotatedAction = databaseAction match {
      case sqlAction: SqlAction[A, NoStream, E] => sqlAction.overrideStatements(sqlAction.statements.map { s =>
        "/* " + comment + " */ " + s
      })
      case otherAction => otherAction
    }

db.run(annotatedAction)

It causes all SQL statements to be prefixed with a comment. You can make the comment be some unique identifier to help you connect SQL to your code, or you could do it automatically by finding a relevant stack frame in Thread.currentThread.getStackTrace before running the query.

Adding comments into Slick

2 Answers2