Slick insert based on previous readings

[Robert Koziol]

Dear all,

I have a standalone application of scala Play Framework. I am trying to perform a DB insert based on the values I have previously read. I read a great number of tutorials and documentation and I analized all these simple examples of slick operations. However I am still stuck with my problem.

I know that if we want to run the DB code sequentially we need to use 'for comprehension'.

My code is something like:

val bookiesOdds = for {
    firstBoxer <- boxerDao.findByName(event.firstBoxer.firstName, event.firstBoxer.middleName, event.firstBoxer.lastName) map {_.getOrElse(throw new NoBoxerException("No boxer " + event.firstBoxer.fullName + " in database!"))}
    secondBoxer <- boxerDao.findByName(event.secondBoxer.firstName, event.secondBoxer.middleName, event.secondBoxer.lastName) map {_.getOrElse(throw new NoBoxerException("No boxer " + event.secondBoxer.fullName + " in database!"))}
    fight <- fightDao.findOrCreateFight(firstBoxer, secondBoxer, new java.sql.Date(event.date.getTime))
    oddsId <- bookiesDao.createOdds(fight.id, event.periods.head.firstOdds.getOrElse(0), event.periods.head.drawOdds, event.periods.head.secondOdds.getOrElse(0), "pinnaclesports")
} yield {
    fight
}

Each dao operation is one db.run call. FirstBoxer and secondBoxer are read from DB without any problem. Then I would like to check if the fight between these boxers already exists. In this case findOrCreateFight should return that fight. Otherwise findOrCreateFight should create a new fight and return this newly created fight. Each case returned fight's id is a parameter for the last call of createOdds function.

So the findOrCreateFight function should look like this:

def findOrCreateFight(firstBoxer: BoxersRow, secondBoxer: BoxersRow, eventDate: java.sql.Date): Future[FightsRow] = {
    for {
        fight <- findByBoxersAndDate(firstBoxer, secondBoxer, eventDate)
        if (fight == None)      
            f <- createAndFindFight(firstBoxer, secondBoxer, eventDate)
    } yield fight.getOrElse(throw new NoFightException("Can not find a fight in DB"))
}

But of course this 'if' condition inside is not possible and it seems that invoking the code invokes createAndFindFight each time which leads for DB's Duplicate entry errors.. Could anyone guide me how to fix the findOrCreateFight function?

Best Regards
 

[Egon Nijns]

You don't need a for comprehension here:
findByBoxersAndDate(firstBoxer, secondBoxer, eventDate).getOrElse(createAndFindFight(firstBoxer, secondBoxer, eventDate)) should do

Op 30-jun.-2016 18:30 schreef "Robert Koziol" <rkoz...@gmail.com>:

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