Re: [Haskelldb-users] Problem using CalendarTimeT column

[Colin P. A. <co...@co...>]

>>>>> "Justin" == Justin Bailey <jgb...@gm...> writes:

The type used is not determined by HaskellDB. Your application
    Justin> determines the type it expects, and the appropriate
    Justin> Convertible instance is selected. If that doesn't make
    Justin> sense, what I mean is the type signature of your result
    Justin> determines the type to which the value will be
    Justin> converted. For example, if your function is named
    Justin> "getTimestampRows", you can control the type converted to
    Justin> via it's signature:


    Justin>   getTimestampRows :: IO [Record (Col1 (Expr Day)) ... )]

    Justin> or

    Justin>   getTimestampRows :: IO [Record (Col1 (Expr ZonedTime))
    Justin> ... )]

    Justin> or

    Justin>   getTimestampRows :: IO [Record (Col1 (Expr UTCTime))
    Justin> ... )]

    Justin> Does that help?

Not really, as I am not actually requesting that column (not
intentioanlly, anyway).
Probably I have got the project call wrong. My code looks like this:

 let q = do
        t <- DB.table IT.imageTable
        DB.project (IT.indexNumber DB.<< t DB.! IT.indexNumber)
        DB.order [DB.desc t IT.indexNumber]
        return t
  rs <- DB.query db q
  let nextIndex = case null rs of
                    True -> 1
                    False -> 1 + (head rs DB.! IT.indexNumber)

I can't say that I could understand the project function from the
examples I saw. Mu intention was just to retrieve the indexNumber
column, which is defined as an integerT in the FieldDesc.
-- 
Colin Adams
Preston Lancashire