Squeryl Dynamic Join Clauses

What I'm looking for seems fairly common but I can't seem to figure it out through the Squeryl api. I need to have a conditional piece to my on statement for a join. def getAllJoin

Solution 1:

If you are simply looking to add a conditional to your where clause, you can do something like this:

on(
   t1.secondary === t2.id and
   (if(hasFallback.isDefined) t1.fallback.isNotNull else 1 === 1.inhibitWhen(true))
)

The inhibitWhen clause should always prevent the output of 1 === 1 from showing up in the actual SQL, but it allows your if/else to return a LogicalBoolean.

Solution 2:

There is a talk related to a similar question on github and a google group:

https://github.com/max-l/Squeryl/pull/168

https://github.com/max-l/Squeryl/pull/144

https://groups.google.com/forum/#!topic/squeryl/BBAXbtRq9v4

If you're using squeryl-0.9.5-6, then you should find a way out by your own. I chose to do (a similar task) the following way:

/** thin wrappwer with no runtime cost */implicitclassRichLogicalBoolean(val e: LogicalBoolean) extends AnyVal {
        def and(condition: Boolean, other: LogicalBoolean) = if (condition) other and e else e
    }

after this, I can write a code like:

t1.secondary === t2.id and
    (yourCondition, t1.fallback.isNotNull)