respect the nullability of columns in generated schema (fix #256) (#276)

server/src-lib/Hasura/GraphQL/Resolve/BoolExp.hs

@@ -80,7 +80,7 @@ parseColExp nt n val = do
   fldInfo <- getFldInfo nt n
   case fldInfo of
     Left  pgColInfo          -> RA.AVCol pgColInfo <$> parseOpExps val
-    Right (relInfo, permExp, _) -> do
+    Right (relInfo, permExp, _, _) -> do
       relBoolExp <- parseBoolExp val
       return $ RA.AVRel relInfo relBoolExp permExp
 

server/src-lib/Hasura/GraphQL/Resolve/Context.hs

@@ -42,7 +42,7 @@ import           Hasura.SQL.Value
 import qualified Hasura.SQL.DML                as S
 
 type FieldMap
-  = Map.HashMap (G.NamedType, G.Name) (Either PGColInfo (RelInfo, S.BoolExp, Maybe Int))
+  = Map.HashMap (G.NamedType, G.Name) (Either PGColInfo (RelInfo, S.BoolExp, Maybe Int, Bool))
 
 data OrdTy
   = OAsc
@@ -64,7 +64,7 @@ type OrdByResolveCtx
 
 getFldInfo
   :: (MonadError QErr m, MonadReader r m, Has FieldMap r)
-  => G.NamedType -> G.Name -> m (Either PGColInfo (RelInfo, S.BoolExp, Maybe Int))
+  => G.NamedType -> G.Name -> m (Either PGColInfo (RelInfo, S.BoolExp, Maybe Int, Bool))
 getFldInfo nt n = do
   fldMap <- asks getter
   onNothing (Map.lookup (nt,n) fldMap) $

server/src-lib/Hasura/GraphQL/Resolve/Mutation.hs

@@ -46,7 +46,7 @@ convertReturning ty selSet =
     case _fName fld of
       "__typename" -> return $ RR.RExp $ G.unName $ G.unNamedType ty
       _ -> do
-        PGColInfo col colTy <- getPGColInfo ty $ _fName fld
+        PGColInfo col colTy _ <- getPGColInfo ty $ _fName fld
         return $ RR.RCol (col, colTy)
 
 convertMutResp

server/src-lib/Hasura/GraphQL/Resolve/Select.hs

@@ -42,8 +42,8 @@ fromSelSet fldTy flds =
       _ -> do
         fldInfo <- getFldInfo fldTy fldName
         case fldInfo of
-          Left (PGColInfo pgCol colTy) -> return (rqlFldName, RS.FCol (pgCol, colTy))
-          Right (relInfo, tableFilter, tableLimit) -> do
+          Left (PGColInfo pgCol colTy _) -> return (rqlFldName, RS.FCol (pgCol, colTy))
+          Right (relInfo, tableFilter, tableLimit, _) -> do
             let relTN = riRTable relInfo
             relSelData <- fromField relTN tableFilter tableLimit fld
             let annRel = RS.AnnRel (riName relInfo) (riType relInfo)
@@ -93,7 +93,7 @@ parseOrderBy v = do
   -- return $ map convOrdByElem enums
   -- undefined
   where
-    convOrdByElem (PGColInfo col _, ordTy, nullsOrd) =
+    convOrdByElem (PGColInfo col _ _, ordTy, nullsOrd) =
       S.OrderByItem (Left col)
       (Just $ convOrdTy ordTy)
       (Just $ convNullsOrd nullsOrd)

server/src-lib/Hasura/GraphQL/Schema.hs

@@ -83,7 +83,7 @@ instance Monoid TyAgg where
   mempty = TyAgg Map.empty Map.empty Map.empty
   mappend = (<>)
 
-type SelField = Either PGColInfo (RelInfo, S.BoolExp, Maybe Int)
+type SelField = Either PGColInfo (RelInfo, S.BoolExp, Maybe Int, Bool)
 
 qualTableToName :: QualifiedTable -> G.Name
 qualTableToName = G.Name <$> \case
@@ -95,7 +95,7 @@ isValidTableName = isValidName . qualTableToName
 
 isValidField :: FieldInfo -> Bool
 isValidField = \case
-  FIColumn (PGColInfo col _) -> isColEligible col
+  FIColumn (PGColInfo col _ _) -> isColEligible col
   FIRelationship (RelInfo rn _ _ remTab _) -> isRelEligible rn remTab
   where
     isColEligible = isValidName . G.Name . getPGColTxt
@@ -114,6 +114,14 @@ mkValidConstraints = filter isValid
     isValid (TableConstraint _ n) =
       isValidName $ G.Name $ getConstraintTxt n
 
+isRelNullable :: FieldInfoMap -> RelInfo -> Bool
+isRelNullable fim ri = isNullable
+  where
+    lCols = map fst $ riMapping ri
+    allCols = getCols fim
+    lColInfos = flip filter allCols $ \ci -> pgiName ci `elem` lCols
+    isNullable = any pgiIsNullable lColInfos
+
 mkCompExpName :: PGColType -> G.Name
 mkCompExpName pgColTy =
   G.Name $ T.pack (show pgColTy) <> "_comparison_exp"
@@ -175,11 +183,14 @@ mkCompExpInp colTy =
       ]
 
 mkPGColFld :: PGColInfo -> ObjFldInfo
-mkPGColFld (PGColInfo colName colTy) =
+mkPGColFld (PGColInfo colName colTy isNullable) =
   ObjFldInfo Nothing n Map.empty ty
   where
     n  = G.Name $ getPGColTxt colName
-    ty = G.toGT $ mkScalarTy colTy
+    ty = bool notNullTy nullTy isNullable
+    scalarTy = mkScalarTy colTy
+    notNullTy = G.toGT $ G.toNT scalarTy
+    nullTy = G.toGT scalarTy
 
 -- where: table_bool_exp
 -- limit: Int
@@ -211,8 +222,8 @@ array_relationship(
 object_relationship: remote_table
 
 -}
-mkRelFld :: RelInfo -> ObjFldInfo
-mkRelFld (RelInfo rn rTy _ remTab _) = case rTy of
+mkRelFld :: RelInfo -> Bool -> ObjFldInfo
+mkRelFld (RelInfo rn rTy _ remTab _) isNullable = case rTy of
   ArrRel ->
     ObjFldInfo (Just "An array relationship") (G.Name $ getRelTxt rn)
     (fromInpValL $ mkSelArgs remTab)
@@ -220,8 +231,9 @@ mkRelFld (RelInfo rn rTy _ remTab _) = case rTy of
   ObjRel ->
     ObjFldInfo (Just "An object relationship") (G.Name $ getRelTxt rn)
     Map.empty
-    (G.toGT relTabTy)
+    objRelTy
   where
+    objRelTy = bool (G.toGT $ G.toNT relTabTy) (G.toGT relTabTy) isNullable
     relTabTy = mkTableTy remTab
 
 {-
@@ -239,8 +251,8 @@ mkTableObj
 mkTableObj tn allowedFlds =
   mkObjTyInfo (Just desc) (mkTableTy tn) $ mapFromL _fiName flds
   where
-    flds = map (either mkPGColFld (mkRelFld . fst')) allowedFlds
-    fst' (a, _, _) = a
+    flds = map (either mkPGColFld mkRelFld') allowedFlds
+    mkRelFld' (relInfo, _, _, isNullable) = mkRelFld relInfo isNullable
     desc = G.Description $
       "columns and relationships of " <>> tn
 
@@ -341,13 +353,13 @@ mkBoolExpInp tn fields =
       ]
 
     mkFldExpInp = \case
-      Left (PGColInfo colName colTy) ->
+      Left (PGColInfo colName colTy _) ->
         mk (G.Name $ getPGColTxt colName) (mkCompExpTy colTy)
-      Right (RelInfo relName _ _ remTab _, _, _) ->
+      Right (RelInfo relName _ _ remTab _, _, _, _) ->
         mk (G.Name $ getRelTxt relName) (mkBoolExpTy remTab)
 
 mkPGColInp :: PGColInfo -> InpValInfo
-mkPGColInp (PGColInfo colName colTy) =
+mkPGColInp (PGColInfo colName colTy _) =
   InpValInfo Nothing (G.Name $ getPGColTxt colName) $
   G.toGT $ mkScalarTy colTy
 
@@ -747,7 +759,7 @@ mkOrdByCtx tn cols =
 mkOrdByEnumsOfCol
   :: PGColInfo
   -> [(G.Name, Text, (PGColInfo, OrdTy, NullsOrder))]
-mkOrdByEnumsOfCol colInfo@(PGColInfo col _) =
+mkOrdByEnumsOfCol colInfo@(PGColInfo col _ _) =
   [ ( colN <> "_asc"
     , "in the ascending order of " <> col <<> ", nulls last"
     , (colInfo, OAsc, NLast)
@@ -831,7 +843,7 @@ mkGCtxRole' tn insColsM selFldsM updColsM delPermM constraints =
 
     nameFromSelFld = \case
       Left colInfo -> G.Name $ getPGColTxt $ pgiName colInfo
-      Right (relInfo, _, _) -> G.Name $ getRelTxt $ riName relInfo
+      Right (relInfo, _, _, _) -> G.Name $ getRelTxt $ riName relInfo
 
     -- helper
     mkColFldMap ty = mapFromL ((ty,) . nameFromSelFld) . map Left
@@ -947,7 +959,11 @@ getSelFlds tableCache fields role selPermInfo =
       let remTableSelPermM =
             Map.lookup role (tiRolePermInfoMap remTableInfo) >>= _permSel
       return $ flip fmap remTableSelPermM $
-        \rmSelPermM -> Right $ (relInfo, spiFilter rmSelPermM, spiLimit rmSelPermM)
+        \rmSelPermM -> Right ( relInfo
+                             , spiFilter rmSelPermM
+                             , spiLimit rmSelPermM
+                             , isRelNullable fields relInfo
+                             )
   where
     allowedCols = spiCols selPermInfo
     getTabInfo tn =
@@ -1011,7 +1027,7 @@ mkGCtxMapTable tableCache (TableInfo tn _ fields rolePerms constraints) = do
     allCols = map pgiName colInfos
     selFlds = flip map (toValidFieldInfos fields) $ \case
       FIColumn pgColInfo     -> Left pgColInfo
-      FIRelationship relInfo -> Right (relInfo, noFilter, Nothing)
+      FIRelationship relInfo -> Right (relInfo, noFilter, Nothing, isRelNullable fields relInfo)
     noFilter = S.BELit True
     adminRootFlds =
       getRootFldsRole' tn constraints fields (Just (tn, [])) (Just (noFilter, Nothing, []))

server/src-lib/Hasura/RQL/DDL/Schema/Diff.hs

@@ -18,23 +18,24 @@ module Hasura.RQL.DDL.Schema.Diff
   , getSchemaChangeDeps
   ) where
 
+import           Hasura.Prelude
 import           Hasura.RQL.Types
 import           Hasura.SQL.Types
-import           Hasura.Prelude
 
-import qualified Database.PG.Query    as Q
+import qualified Database.PG.Query   as Q
 
 import           Data.Aeson.Casing
 import           Data.Aeson.TH
 
-import qualified Data.HashMap.Strict  as M
-import qualified Data.HashSet         as HS
+import qualified Data.HashMap.Strict as M
+import qualified Data.HashSet        as HS
 
 data PGColMeta
   = PGColMeta
   { pcmColumnName      :: !PGCol
   , pcmOrdinalPosition :: !Int
   , pcmDataType        :: !PGColType
+  , pcmIsNullable      :: !Bool
   } deriving (Show, Eq)
 
 $(deriveJSON (aesonDrop 3 snakeCase){omitNothingFields=True} ''PGColMeta)
@@ -80,7 +81,7 @@ fetchTableMeta = do
         (SELECT
              table_schema,
              table_name,
-             json_agg((SELECT r FROM (SELECT column_name, udt_name AS data_type, ordinal_position) r)) as columns
+             json_agg((SELECT r FROM (SELECT column_name, udt_name AS data_type, ordinal_position, is_nullable::boolean) r)) as columns
          FROM
              information_schema.columns
          GROUP BY
@@ -141,8 +142,8 @@ getTableDiff oldtm newtm =
 
     existingCols = getOverlap pcmOrdinalPosition oldCols newCols
 
-    pcmToPci (PGColMeta colName _ colType)
-      = PGColInfo colName colType
+    pcmToPci (PGColMeta colName _ colType isNullable)
+      = PGColInfo colName colType isNullable
 
     alteredCols =
       flip map (filter (uncurry (/=)) existingCols) $ \(pcmo, pcmn) ->

server/src-lib/Hasura/RQL/DDL/Schema/Table.hs

@@ -62,7 +62,7 @@ getTableInfo qt@(QualifiedTable sn tn) isSystemDefined = do
 
   -- Fetch the column details
   colData <- Q.catchE defaultTxErrorHandler $ Q.listQ [Q.sql|
-            SELECT column_name, to_json(udt_name)
+            SELECT column_name, to_json(udt_name), is_nullable::boolean
               FROM information_schema.columns
              WHERE table_schema = $1
                AND table_name = $2
@@ -76,7 +76,8 @@ getTableInfo qt@(QualifiedTable sn tn) isSystemDefined = do
                AND table_name = $2
                            |] (sn, tn) False
   return $ mkTableInfo qt isSystemDefined rawConstraints $
-    map (fmap Q.getAltJ) colData
+    flip map colData $ \(colName, Q.AltJ colTy, isNull)
+                       -> (colName, colTy, isNull)
 
 newtype TrackTable
   = TrackTable
@@ -142,7 +143,7 @@ processTableChanges ti tableDiff = do
     delFldFromCache (fromPGCol droppedCol) tn
 
   -- In the newly added columns check that there is no conflict with relationships
-  forM_ addedCols $ \colInfo@(PGColInfo colName _) ->
+  forM_ addedCols $ \colInfo@(PGColInfo colName _ _) ->
     case M.lookup (fromPGCol colName) $ tiFieldInfoMap ti of
       Just (FIRelationship _) ->
         throw400 AlreadyExists $ "cannot add column " <> colName
@@ -152,7 +153,7 @@ processTableChanges ti tableDiff = do
 
   sc <- askSchemaCache
   -- for rest of the columns
-  forM_ alteredCols $ \(PGColInfo oColName oColTy, nci@(PGColInfo nColName nColTy)) ->
+  forM_ alteredCols $ \(PGColInfo oColName oColTy _, nci@(PGColInfo nColName nColTy _)) ->
     if | oColName /= nColName ->
            throw400 NotSupported $ "column renames are not yet supported : " <>
              tn <<> "." <>> oColName

server/src-lib/Hasura/RQL/DML/Internal.hs

@@ -182,7 +182,7 @@ checkOnColExp :: (P1C m)
               => SelPermInfo -> AnnValS -> m AnnValS
 checkOnColExp spi annVal =
   case annVal of
-    AVCol pci@(PGColInfo cn _) opExps -> do
+    AVCol pci@(PGColInfo cn _ _) opExps -> do
       checkSelOnCol spi cn
       return $ AVCol pci opExps
     AVRel relInfo nesAnn _ -> do

server/src-lib/Hasura/RQL/GBoolExp.hs

@@ -227,7 +227,7 @@ parseOpExps
   -> PGColInfo
   -> Value
   -> m [OpExpG a]
-parseOpExps valParser cim (PGColInfo cn colTy) (Object o) =
+parseOpExps valParser cim (PGColInfo cn colTy _) (Object o) =
   forM (M.toList o) $ \(k, v) -> do
   op <- parseOp k
   case (op, v) of
@@ -245,7 +245,7 @@ parseOpExps valParser cim (PGColInfo cn colTy) (Object o) =
         "incompatible column types : " <> cn <<> ", " <>> pgCol
       return $ OECol colOp pgCol
     (Right _, _) -> throw400 UnexpectedPayload "expecting a string for column operator"
-parseOpExps valParser _ (PGColInfo _ colTy) val = do
+parseOpExps valParser _ (PGColInfo _ colTy _) val = do
   annValOp <- parseAnnOpExpG valParser REQ colTy val
   return [OEVal annValOp]
 
@@ -330,9 +330,9 @@ annColExp
 annColExp valueParser colInfoMap (ColExp fieldName colVal) = do
   colInfo <- askFieldInfo colInfoMap fieldName
   case colInfo of
-    FIColumn (PGColInfo _ PGJSON) ->
+    FIColumn (PGColInfo _ PGJSON _) ->
       throwError (err400 UnexpectedPayload "JSON column can not be part of where clause")
-    FIColumn (PGColInfo _ PGJSONB) ->
+    FIColumn (PGColInfo _ PGJSONB _) ->
       throwError (err400 UnexpectedPayload "JSONB column can not be part of where clause")
     FIColumn pgi ->
       AVCol pgi <$> parseOpExps valueParser colInfoMap pgi colVal
@@ -356,7 +356,7 @@ convColRhs
   => BoolExpBuilder m a
   -> S.Qual -> AnnValO a -> m (AnnValG S.BoolExp)
 convColRhs bExpBuilder tableQual annVal = case annVal of
-  AVCol pci@(PGColInfo cn _) opExps -> do
+  AVCol pci@(PGColInfo cn _ _) opExps -> do
     let qualColExp = S.SEQIden $ S.QIden tableQual (toIden cn)
     bExps <- forM opExps $ \case
       OEVal annOpValExp -> bExpBuilder qualColExp annOpValExp

server/src-lib/Hasura/RQL/Types/SchemaCache.hs

@@ -179,8 +179,9 @@ type QTemplateCache = M.HashMap TQueryName QueryTemplateInfo
 
 data PGColInfo
   = PGColInfo
-  { pgiName :: !PGCol
-  , pgiType :: !PGColType
+  { pgiName       :: !PGCol
+  , pgiType       :: !PGColType
+  , pgiIsNullable :: !Bool
   } deriving (Show, Eq)
 
 $(deriveToJSON (aesonDrop 3 snakeCase) ''PGColInfo)
@@ -371,13 +372,13 @@ data TableInfo
 $(deriveToJSON (aesonDrop 2 snakeCase) ''TableInfo)
 
 mkTableInfo :: QualifiedTable -> Bool -> [(ConstraintType, ConstraintName)]
-            -> [(PGCol, PGColType)] -> TableInfo
+            -> [(PGCol, PGColType, Bool)] -> TableInfo
 mkTableInfo tn isSystemDefined rawCons cols =
   TableInfo tn isSystemDefined colMap (M.fromList []) constraints
   where
     constraints = flip map rawCons $ uncurry TableConstraint
     colMap     = M.fromList $ map f cols
-    f (cn, ct) = (fromPGCol cn, FIColumn $ PGColInfo cn ct)
+    f (cn, ct, b) = (fromPGCol cn, FIColumn $ PGColInfo cn ct b)
 
 type TableCache = M.HashMap QualifiedTable TableInfo -- info of all tables