diff --git a/apiary-persistent.cabal b/apiary-persistent.cabal
--- a/apiary-persistent.cabal
+++ b/apiary-persistent.cabal
@@ -1,5 +1,5 @@
 name:                apiary-persistent
-version:             0.8.0.0
+version:             0.9.0.0
 synopsis:            persistent support for apiary web framework.
 description:
   example: <https://github.com/philopon/apiary/blob/master/examples/persistent.hs>
@@ -21,9 +21,10 @@
   other-modules:       
   build-depends:       base               >=4.6   && <4.8
                      , persistent         >=1.3   && <1.4
+                     , apiary             >=0.9   && <0.10
                      , monad-logger       >=0.3   && <0.4
                      , resourcet          >=1.1   && <1.2
-                     , mtl                >=2.1   && <2.2
+                     , mtl                >=2.1   && <2.3
                      , reflection         >=1.4   && <1.5
                      , transformers-base  >=0.4   && <0.5
 
diff --git a/src/Web/Apiary/Database/Persist.hs b/src/Web/Apiary/Database/Persist.hs
--- a/src/Web/Apiary/Database/Persist.hs
+++ b/src/Web/Apiary/Database/Persist.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE Rank2Types #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE TypeFamilies #-}
 
 module Web.Apiary.Database.Persist (
     -- * runner
@@ -14,26 +15,54 @@
     -- * types
     , HasPersist
 
+    -- * filter
+    , sql
+    , BoolLike(..)
+
     -- * reexport
     , module Database.Persist.Sql
     ) where
 
 import Database.Persist.Sql
+import Web.Apiary
+import Control.Applicative
 import Control.Monad.Trans.Resource
 import Data.Reflection
+import Data.Apiary.SList
+import Control.Monad.Apiary.Filter.Internal
 
-type HasPersist = Given ApiaryPersistState
+type HasPersist = Given Persist
 
-newtype ApiaryPersistState = ApiaryPersistState
+newtype Persist = Persist
     { getPool    :: ConnectionPool
     }
 
 runSql :: (MonadBaseControl IO m, HasPersist) => SqlPersistT (ResourceT m) a -> m a
-runSql a =
-    runResourceT $
-    runSqlPool a (getPool given)
+runSql a = runResourceT $ runSqlPool a (getPool given)
 
 withWithSqlPool :: (forall a. (ConnectionPool -> m a) -> m a)
                 -> (HasPersist => m b) -> m b
 withWithSqlPool with m = with $ \pool -> 
-    give (ApiaryPersistState pool) m
+    give (Persist pool) m
+
+class BoolLike a where
+  type UnBool a
+  unBool :: a -> Maybe (UnBool a)
+
+instance BoolLike (Maybe a) where
+    type UnBool (Maybe a) = a
+    unBool = id
+
+instance BoolLike [a] where
+    type UnBool [a] = [a]
+    unBool [] = Nothing
+    unBool a  = Just a
+
+-- | filter by sql query. since 0.9.0.0.
+sql :: (BoolLike a, Functor n, Monad n, MonadBaseControl IO (ActionT n), HasPersist)
+    => SqlPersistT (ResourceT (ActionT n)) a
+    -> ApiaryT (Snoc as (UnBool a)) n m b
+    -> ApiaryT as n m b
+sql p = focus $ \l -> do
+    r <- runSql p
+    maybe empty (\i -> return $ sSnoc l i) $ unBool r