Dynamic limit and offset

Author: shane-circuithub

cabal.project

@@ -1,3 +1,3 @@
-packages: .
+packages: ., ../opaleye/*.cabal
 constraints: ansi-wl-pprint < 1.0.0
 allow-newer: base16:base, base16:deepseq, base16:text

src/Rel8/Query/Limit.hs

@@ -1,27 +1,39 @@
+{-# language LambdaCase #-}
+
 module Rel8.Query.Limit
   ( limit
   , offset
   )
 where
 
 -- base
+import Data.Int (Int64)
 import Prelude
 
 -- opaleye
 import qualified Opaleye
+import qualified Opaleye.Internal.HaskellDB.PrimQuery as Opaleye
 
 -- rel8
+import Rel8.Expr (Expr)
+import Rel8.Expr.Opaleye (toColumn, toPrimExpr)
 import Rel8.Query ( Query )
 import Rel8.Query.Opaleye ( mapOpaleye )
 
 
 -- | @limit n@ select at most @n@ rows from a query.  @limit n@ is equivalent
 -- to the SQL @LIMIT n@.
-limit :: Word -> Query a -> Query a
-limit = mapOpaleye . Opaleye.limit . fromIntegral
+limit :: Expr Int64 -> Query a -> Query a
+limit = mapOpaleye . Opaleye.limitField . toColumn . stripCast . toPrimExpr
 
 
 -- | @offset n@ drops the first @n@ rows from a query. @offset n@ is equivalent
 -- to the SQL @OFFSET n@.
-offset :: Word -> Query a -> Query a
-offset = mapOpaleye . Opaleye.offset . fromIntegral
+offset :: Expr Int64 -> Query a -> Query a
+offset = mapOpaleye . Opaleye.offsetField . toColumn . stripCast . toPrimExpr
+
+
+stripCast :: Opaleye.PrimExpr -> Opaleye.PrimExpr
+stripCast = \case
+  Opaleye.CastExpr "\"int8\"" a -> a
+  a -> a