khibino/haskell-relational-record
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Add placeholder.

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This commit is contained in:
Kei Hibino 2013-05-02 18:44:38 +09:00
parent 14c6cd58ca
commit e254f11903
1 changed files with 22 additions and 4 deletions
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26
relational-join/src/Database/Relational/Query/Projection.hs
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@ -14,7 +14,10 @@ module Database.Relational.Query.Projection (
valueProjection,
ValueProjectable (value),
valueTrue, valueFalse, valueNull
valueTrue, valueFalse,
SqlProjectable (unsafeSqlValue),
valueNull, placeholder
) where
import Prelude hiding ((!!))
@ -125,9 +128,11 @@ instance ProjectableMaybe Projection where
instance ProjectableMaybe Expr where
p !? pi' = toExpr $ p `projectMaybe` pi'
unsafeSqlProjection :: String -> Projection (Singleton t)
unsafeSqlProjection = unsafeFromColumns . (:[])
valueProjection :: ShowConstantSQL t => t -> Projection (Singleton t)
valueProjection = unsafeFromColumns . (:[]) . showConstantSQL
valueProjection = unsafeSqlProjection . showConstantSQL
class ValueProjectable p where
value :: (ShowConstantSQL t) => t -> p (Singleton t)
@ -145,5 +150,18 @@ valueTrue = value True
valueFalse :: ValueProjectable p => p (Singleton Bool)
valueFalse = value False
valueNull :: (ValueProjectable p, ShowConstantSQL a) => p (Singleton (Maybe a))
valueNull = value Nothing
class SqlProjectable p where
unsafeSqlValue :: String -> p (Singleton t)
instance SqlProjectable Projection where
unsafeSqlValue = unsafeSqlProjection
instance SqlProjectable Expr where
unsafeSqlValue = UnsafeExpr.Expr
valueNull :: SqlProjectable p => p (Singleton (Maybe a))
valueNull = unsafeSqlValue "NULL"
placeholder :: SqlProjectable p => p (Singleton t)
placeholder = unsafeSqlValue "?"