graphql-engine/server/src-lib/Hasura/RQL/IR/OrderBy.hs
2023-04-24 18:37:33 +00:00

66 lines
1.5 KiB
Haskell

module Hasura.RQL.IR.OrderBy
( OrderByCol (..),
OrderByItemG (..),
OrderByItem,
-- used by RQL.DML.Types
orderByColFromTxt,
)
where
import Data.Aeson
import Data.Text qualified as T
import Hasura.Prelude
import Hasura.RQL.Types.Backend
import Hasura.RQL.Types.BackendType
import Hasura.RQL.Types.Common
-- order by col
data OrderByCol
= OCPG FieldName
| OCRel FieldName OrderByCol
deriving (Show, Eq)
instance FromJSON OrderByCol where
parseJSON = \case
(String t) -> orderByColFromToks $ T.split (== '.') t
v -> parseJSON v >>= orderByColFromToks
orderByColFromToks ::
(MonadFail m) =>
[Text] ->
m OrderByCol
orderByColFromToks toks = do
when (any T.null toks) $ fail "col/rel cannot be empty"
case toks of
[] -> fail "failed to parse an OrderByCol: found empty cols"
x : xs -> return $ go (FieldName x) xs
where
go fld = \case
[] -> OCPG fld
x : xs -> OCRel fld $ go (FieldName x) xs
orderByColFromTxt ::
(MonadFail m) =>
Text ->
m OrderByCol
orderByColFromTxt =
orderByColFromToks . T.split (== '.')
-- order by item
data OrderByItemG (b :: BackendType) a = OrderByItemG
{ obiType :: Maybe (BasicOrderType b),
obiColumn :: a,
obiNulls :: Maybe (NullsOrderType b)
}
deriving (Functor, Foldable, Traversable, Generic)
deriving instance (Backend b, Show a) => Show (OrderByItemG b a)
deriving instance (Backend b, Eq a) => Eq (OrderByItemG b a)
instance (Backend b, Hashable a) => Hashable (OrderByItemG b a)
type OrderByItem b = OrderByItemG b OrderByCol