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scalasqueryl

Booleans in Squeryl dynamic queries

I'm trying to use Squeryl (0.9.4 for scala 2.8.1) dynamic queries (.? and inhibitWhen(...)). They are working fine while I'm using String/Int/whatever fields, but seem to interfere with squeryl's syntax sugar for boolean conditions.

Assuming we have a is_trusted: Option[Boolean] defined somewhere, the following code

where ( obj => 
  obj.is_trusted === is_trusted.?
)

does not compile, throwing the following error:

... type mismatch;
[error]  found   : org.squeryl.dsl.ast.LogicalBoolean
[error]  required: org.squeryl.dsl.NonNumericalExpression[org.squeryl.PrimitiveTypeMode.BooleanType]
[error]     obj.is_trusted === is_trusted.?
[error]                                   ^

even this one does not work, failing on the first condition:

where ( obj => 
  obj.is_trusted.inhibitWhen(is_trusted == Some(true)) and
  not(obj.is_trusted).inhibitWhen(is_trusted == Some(false))
)

The only working version uses double not as a hint for the compiler:

not(not(obj.is_trusted)).inhibitWhen(is_trusted != Some(true)) and
not(obj.is_trusted).inhibitWhen(is_trusted != Some(false))

Is there a more sane way to do dynamic queries with booleans?

Solution

  • Hmm... I think this is probably another bug caused by an implicit conversion from Boolean -> LogicalBoolean. That feature has been deprecated in 0.9.5 because of issues similar to this. What the .? should do is trigger an implicit conversion from Boolean -> BooleanExpression but since LogicalBoolean has a .? method as well there is a conflict and the latter appears to be have precedence. I know it's not terribly pretty, but try this:

    where ( obj => 
  obj.is_trusted === is_trusted.~.?
)

    The .~ should force the conversion to BooleanExpression[Option[Boolean]] before .? is invoked.