{-# LANGUAGE ViewPatterns #-} -- | This module defines translation functions for queries which select data. -- Principally this includes translating the @query@ root field, but parts are -- also reused for serving the responses for mutations. module Hasura.Backends.MSSQL.FromIr.Query ( fromQueryRootField, fromSelect, fromSourceRelationship, ) where import Control.Applicative (getConst) import Control.Monad.Validate import Data.Aeson.Extended qualified as J import Data.HashMap.Strict qualified as HM import Data.List.NonEmpty qualified as NE import Data.Map.Strict (Map) import Data.Map.Strict qualified as M import Data.Proxy import Data.Text.NonEmpty (mkNonEmptyTextUnsafe) import Database.ODBC.SQLServer qualified as ODBC import Hasura.Backends.MSSQL.FromIr ( Error (..), FromIr, NameTemplate (..), generateAlias, ) import Hasura.Backends.MSSQL.Instances.Types () import Hasura.Backends.MSSQL.Types.Internal as TSQL import Hasura.Prelude import Hasura.RQL.IR qualified as IR import Hasura.RQL.Types.Column qualified as IR import Hasura.RQL.Types.Common qualified as IR import Hasura.RQL.Types.Relationships.Local qualified as IR import Hasura.SQL.Backend -- | This is the top-level entry point for translation of Query root fields. fromQueryRootField :: IR.QueryDB 'MSSQL Void Expression -> FromIr Select fromQueryRootField = \case (IR.QDBSingleRow s) -> fromSelect IR.JASSingleObject s (IR.QDBMultipleRows s) -> fromSelect IR.JASMultipleRows s (IR.QDBAggregation s) -> fromSelectAggregate Nothing s fromSelect :: IR.JsonAggSelect -> IR.AnnSelectG 'MSSQL (IR.AnnFieldG 'MSSQL Void) Expression -> FromIr TSQL.Select fromSelect jsonAggSelect annSimpleSel = case jsonAggSelect of IR.JASMultipleRows -> guardSelectYieldingNull emptyArrayExpression <$> fromSelectRows annSimpleSel IR.JASSingleObject -> fmap (guardSelectYieldingNull nullExpression) $ fromSelectRows annSimpleSel <&> \sel -> sel { selectFor = JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = NoRoot}, selectTop = Top 1 } where guardSelectYieldingNull :: TSQL.Expression -> TSQL.Select -> TSQL.Select guardSelectYieldingNull fallbackExpression select = let isNullApplication = FunExpISNULL (SelectExpression select) fallbackExpression in emptySelect { selectProjections = [ ExpressionProjection $ Aliased { aliasedThing = FunctionApplicationExpression isNullApplication, aliasedAlias = "root" } ] } -- | Used in 'Hasura.Backends.MSSQL.Plan.planSourceRelationship', which is in -- turn used by to implement `mkDBRemoteRelationship' for 'BackendExecute'. -- For more information, see the module/documentation of 'Hasura.GraphQL.Execute.RemoteJoin.Source'. fromSourceRelationship :: -- | List of json objects, each of which becomes a row of the table NE.NonEmpty J.Object -> -- | The above objects have this schema HM.HashMap IR.FieldName (ColumnName, ScalarType) -> IR.FieldName -> (IR.FieldName, IR.SourceRelationshipSelection 'MSSQL Void (Const Expression)) -> FromIr TSQL.Select fromSourceRelationship lhs lhsSchema argumentId relationshipField = do (argumentIdQualified, fieldSource) <- flip runReaderT (fromAlias selectFrom) $ do argumentIdQualified <- fromColumn (coerceToColumn argumentId) relationshipSource <- fromRemoteRelationFieldsG mempty (fst <$> joinColumns) relationshipField pure (ColumnExpression argumentIdQualified, relationshipSource) let selectProjections = [projectArgumentId argumentIdQualified, fieldSourceProjections fieldSource] pure Select { selectWith = Nothing, selectOrderBy = Nothing, selectTop = NoTop, selectProjections, selectFrom = Just selectFrom, selectJoins = mapMaybe fieldSourceJoin $ pure fieldSource, selectWhere = mempty, selectFor = JsonFor ForJson {jsonCardinality = JsonArray, jsonRoot = NoRoot}, selectOffset = Nothing } where projectArgumentId column = ExpressionProjection $ Aliased { aliasedThing = column, aliasedAlias = IR.getFieldNameTxt argumentId } selectFrom = FromOpenJson Aliased { aliasedThing = OpenJson { openJsonExpression = ValueExpression (ODBC.TextValue $ lbsToTxt $ J.encode lhs), openJsonWith = Just $ toJsonFieldSpec argumentId IntegerType NE.:| map (uncurry toJsonFieldSpec . second snd) (HM.toList lhsSchema) }, aliasedAlias = "lhs" } joinColumns = mapKeys coerceToColumn lhsSchema coerceToColumn = ColumnName . IR.getFieldNameTxt toJsonFieldSpec (IR.FieldName lhsFieldName) scalarType = ScalarField scalarType DataLengthMax lhsFieldName (Just $ FieldPath RootPath lhsFieldName) -- | Build the 'FieldSource' for the relation field, depending on whether it's -- an object, array, or aggregate relationship. fromRemoteRelationFieldsG :: Map TableName EntityAlias -> HM.HashMap ColumnName ColumnName -> (IR.FieldName, IR.SourceRelationshipSelection 'MSSQL Void (Const Expression)) -> ReaderT EntityAlias FromIr FieldSource fromRemoteRelationFieldsG existingJoins joinColumns (IR.FieldName name, field) = case field of IR.SourceRelationshipObject selectionSet -> fmap ( \aliasedThing -> JoinFieldSource JsonSingleton (Aliased {aliasedThing, aliasedAlias = name}) ) ( fromObjectRelationSelectG existingJoins ( withJoinColumns $ runIdentity $ traverse (Identity . getConst) selectionSet ) ) IR.SourceRelationshipArray selectionSet -> fmap ( \aliasedThing -> JoinFieldSource JsonArray (Aliased {aliasedThing, aliasedAlias = name}) ) ( fromArraySelectG ( IR.ASSimple $ withJoinColumns $ runIdentity $ traverse (Identity . getConst) selectionSet ) ) IR.SourceRelationshipArrayAggregate selectionSet -> fmap ( \aliasedThing -> JoinFieldSource JsonArray (Aliased {aliasedThing, aliasedAlias = name}) ) ( fromArraySelectG ( IR.ASAggregate $ withJoinColumns $ runIdentity $ traverse (Identity . getConst) selectionSet ) ) where withJoinColumns :: s -> IR.AnnRelationSelectG 'MSSQL s withJoinColumns annotatedRelationship = IR.AnnRelationSelectG (IR.RelName $ mkNonEmptyTextUnsafe name) joinColumns annotatedRelationship -- | Top/root-level 'Select'. All descendent/sub-translations are collected to produce a root TSQL.Select. fromSelectRows :: IR.AnnSelectG 'MSSQL (IR.AnnFieldG 'MSSQL Void) Expression -> FromIr TSQL.Select fromSelectRows annSelectG = do selectFrom <- case from of IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject IR.FromIdentifier identifier -> pure $ FromIdentifier $ IR.unFIIdentifier identifier IR.FromFunction {} -> refute $ pure FunctionNotSupported Args { argsOrderBy, argsWhere, argsJoins, argsTop, argsDistinct = Proxy, argsOffset, argsExistingJoins } <- runReaderT (fromSelectArgsG args) (fromAlias selectFrom) fieldSources <- runReaderT (traverse (fromAnnFieldsG argsExistingJoins stringifyNumbers) fields) (fromAlias selectFrom) filterExpression <- runReaderT (fromGBoolExp permFilter) (fromAlias selectFrom) let selectProjections = map fieldSourceProjections fieldSources pure $ emptySelect { selectOrderBy = argsOrderBy, selectTop = permissionBasedTop <> argsTop, selectProjections, selectFrom = Just selectFrom, selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources, selectWhere = argsWhere <> Where [filterExpression], selectFor = JsonFor ForJson {jsonCardinality = JsonArray, jsonRoot = NoRoot}, selectOffset = argsOffset } where IR.AnnSelectG { _asnFields = fields, _asnFrom = from, _asnPerm = perm, _asnArgs = args, _asnStrfyNum = stringifyNumbers } = annSelectG IR.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm permissionBasedTop = maybe NoTop Top mPermLimit mkNodesSelect :: Args -> Where -> Expression -> Top -> From -> [(Int, (IR.FieldName, [FieldSource]))] -> [(Int, Projection)] mkNodesSelect Args {..} foreignKeyConditions filterExpression permissionBasedTop selectFrom nodes = [ ( index, ExpressionProjection $ Aliased { aliasedThing = SelectExpression $ emptySelect { selectProjections = map fieldSourceProjections fieldSources, selectTop = permissionBasedTop <> argsTop, selectFrom = pure selectFrom, selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources, selectWhere = argsWhere <> Where [filterExpression] <> foreignKeyConditions, selectFor = JsonFor ForJson {jsonCardinality = JsonArray, jsonRoot = NoRoot}, selectOrderBy = argsOrderBy, selectOffset = argsOffset }, aliasedAlias = IR.getFieldNameTxt fieldName } ) | (index, (fieldName, fieldSources)) <- nodes ] -- -- The idea here is that LIMIT/OFFSET and aggregates don't mix -- well. Therefore we have a nested query: -- -- select sum(*), .. FROM (select * from x offset o limit l) p -- -- That's why @projections@ appears on the outer, and is a -- @StarProjection@ for the inner. But the joins, conditions, top, -- offset are on the inner. -- mkAggregateSelect :: Args -> Where -> Expression -> From -> [(Int, (IR.FieldName, [Projection]))] -> [(Int, Projection)] mkAggregateSelect Args {..} foreignKeyConditions filterExpression selectFrom aggregates = [ ( index, ExpressionProjection $ Aliased { aliasedThing = safeJsonQueryExpression JsonSingleton $ SelectExpression $ emptySelect { selectProjections = projections, selectTop = NoTop, selectFrom = pure $ FromSelect Aliased { aliasedAlias = aggSubselectName, aliasedThing = emptySelect { selectProjections = pure StarProjection, selectTop = argsTop, selectFrom = pure selectFrom, selectJoins = argsJoins, selectWhere = argsWhere <> Where [filterExpression] <> foreignKeyConditions, selectFor = NoFor, selectOrderBy = mempty, selectOffset = argsOffset } }, selectJoins = mempty, selectWhere = mempty, selectFor = JsonFor ForJson { jsonCardinality = JsonSingleton, jsonRoot = NoRoot }, selectOrderBy = mempty, selectOffset = Nothing }, aliasedAlias = IR.getFieldNameTxt fieldName } ) | (index, (fieldName, projections)) <- aggregates ] fromSelectAggregate :: Maybe (EntityAlias, HashMap ColumnName ColumnName) -> IR.AnnSelectG 'MSSQL (IR.TableAggregateFieldG 'MSSQL Void) Expression -> FromIr TSQL.Select fromSelectAggregate mparentRelationship IR.AnnSelectG { _asnFields = (zip [0 ..] -> fields), _asnFrom = from, _asnPerm = IR.TablePerm {_tpLimit = (maybe NoTop Top -> permissionBasedTop), _tpFilter = permFilter}, _asnArgs = args, _asnStrfyNum = stringifyNumbers } = do selectFrom <- case from of IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject IR.FromIdentifier identifier -> pure $ FromIdentifier $ IR.unFIIdentifier identifier IR.FromFunction {} -> refute $ pure FunctionNotSupported -- Below: When we're actually a RHS of a query (of CROSS APPLY), -- then we'll have a LHS table that we're joining on. So we get the -- conditions expressions from the field mappings. The LHS table is -- the entityAlias, and the RHS table is selectFrom. mforeignKeyConditions <- fmap (Where . fromMaybe []) $ for mparentRelationship $ \(entityAlias, mapping) -> runReaderT (fromMapping selectFrom mapping) entityAlias filterExpression <- runReaderT (fromGBoolExp permFilter) (fromAlias selectFrom) args'@Args {argsExistingJoins} <- runReaderT (fromSelectArgsG args) (fromAlias selectFrom) -- Although aggregates, exps and nodes could be handled in one list, -- we need to separately treat the subselect expressions expss :: [(Int, Projection)] <- flip runReaderT (fromAlias selectFrom) $ sequence $ mapMaybe fromTableExpFieldG fields nodes :: [(Int, (IR.FieldName, [FieldSource]))] <- flip runReaderT (fromAlias selectFrom) $ sequence $ mapMaybe (fromTableNodesFieldG argsExistingJoins stringifyNumbers) fields let aggregates :: [(Int, (IR.FieldName, [Projection]))] = mapMaybe fromTableAggFieldG fields pure emptySelect { selectProjections = map snd $ sortBy (comparing fst) $ expss <> mkNodesSelect args' mforeignKeyConditions filterExpression permissionBasedTop selectFrom nodes <> mkAggregateSelect args' mforeignKeyConditions filterExpression selectFrom aggregates, selectTop = NoTop, selectFrom = pure $ FromOpenJson $ Aliased { aliasedThing = OpenJson { openJsonExpression = ValueExpression $ ODBC.TextValue "[0]", openJsonWith = Nothing }, aliasedAlias = existsFieldName }, selectJoins = mempty, -- JOINs and WHEREs are only relevant in subselects selectWhere = mempty, selectFor = JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = NoRoot}, selectOrderBy = Nothing, selectOffset = Nothing } -------------------------------------------------------------------------------- -- GraphQL Args data Args = Args { argsWhere :: Where, argsOrderBy :: Maybe (NonEmpty OrderBy), argsJoins :: [Join], argsTop :: Top, argsOffset :: Maybe Expression, argsDistinct :: Proxy (Maybe (NonEmpty FieldName)), argsExistingJoins :: Map TableName EntityAlias } deriving (Show) fromSelectArgsG :: IR.SelectArgsG 'MSSQL Expression -> ReaderT EntityAlias FromIr Args fromSelectArgsG selectArgsG = do let argsOffset = ValueExpression . ODBC.IntValue . fromIntegral <$> moffset argsWhere <- maybe (pure mempty) (fmap (Where . pure) . fromGBoolExp) mannBoolExp argsTop <- maybe (pure mempty) (pure . Top) mlimit -- Not supported presently, per Vamshi: -- -- > It is hardly used and we don't have to go to great lengths to support it. -- -- But placeholdering the code so that when it's ready to be used, -- you can just drop the Proxy wrapper. let argsDistinct = Proxy (argsOrderBy, joins) <- runWriterT (traverse fromAnnotatedOrderByItemG (maybe [] toList orders)) -- Any object-relation joins that we generated, we record their -- generated names into a mapping. let argsExistingJoins = M.fromList (mapMaybe unfurledObjectTableAlias (toList joins)) pure Args { argsJoins = toList (fmap unfurledJoin joins), argsOrderBy = nonEmpty argsOrderBy, .. } where IR.SelectArgs { _saWhere = mannBoolExp, _saLimit = mlimit, _saOffset = moffset, _saOrderBy = orders } = selectArgsG -------------------------------------------------------------------------------- -- Conversion functions fromQualifiedTable :: TableName -> FromIr From fromQualifiedTable schemadTableName@(TableName {tableName}) = do alias <- generateAlias (TableTemplate tableName) pure ( FromQualifiedTable ( Aliased { aliasedThing = schemadTableName, aliasedAlias = alias } ) ) -- | Translate an 'AnnBoolExpFld' within an 'EntityAlias' context referring to the table the `AnnBoolExpFld` field belongs to. -- -- This is mutually recursive with 'fromGBoolExp', mirroring the mutually recursive structure between 'AnnBoolExpFld' and 'AnnBoolExp b a' (alias of 'GBoolExp b (AnnBoolExpFld b a)'). fromAnnBoolExpFld :: IR.AnnBoolExpFld 'MSSQL Expression -> ReaderT EntityAlias FromIr Expression fromAnnBoolExpFld = \case IR.AVColumn columnInfo opExpGs -> do expression <- fromColumnInfoForBoolExp columnInfo expressions <- traverse (lift . fromOpExpG expression) opExpGs pure (AndExpression expressions) IR.AVRelationship IR.RelInfo {riMapping = mapping, riRTable = table} annBoolExp -> do selectFrom <- lift (fromQualifiedTable table) foreignKeyConditions <- fromMapping selectFrom mapping whereExpression <- local (const (fromAlias selectFrom)) (fromGBoolExp annBoolExp) pure ( ExistsExpression emptySelect { selectOrderBy = Nothing, selectProjections = [ ExpressionProjection ( Aliased { aliasedThing = trueExpression, aliasedAlias = existsFieldName } ) ], selectFrom = Just selectFrom, selectJoins = mempty, selectWhere = Where (foreignKeyConditions <> [whereExpression]), selectTop = NoTop, selectFor = NoFor, selectOffset = Nothing } ) -- | For boolean operators, various comparison operators used need -- special handling to ensure that SQL Server won't outright reject -- the comparison. See also 'shouldCastToVarcharMax'. fromColumnInfoForBoolExp :: IR.ColumnInfo 'MSSQL -> ReaderT EntityAlias FromIr Expression fromColumnInfoForBoolExp IR.ColumnInfo {ciColumn = column, ciType} = do fieldName <- columnNameToFieldName column <$> ask if shouldCastToVarcharMax ciType -- See function commentary. then pure (CastExpression (ColumnExpression fieldName) WvarcharType DataLengthMax) else pure (ColumnExpression fieldName) -- | There's a problem of comparing text fields with =, <, etc. that -- SQL Server completely refuses to do so. So one way to workaround -- this restriction is to automatically cast such text fields to -- varchar(max). shouldCastToVarcharMax :: IR.ColumnType 'MSSQL -> Bool shouldCastToVarcharMax typ = typ == IR.ColumnScalar TextType || typ == IR.ColumnScalar WtextType -------------------------------------------------------------------------------- -- Sources of projected fields -- -- Because in the IR, a field projected can be a foreign object, we -- have to both generate a projection AND on the side generate a join. -- -- So a @FieldSource@ couples the idea of the projected thing and the -- source of it (via 'Aliased'). data FieldSource = ExpressionFieldSource (Aliased Expression) | JoinFieldSource JsonCardinality (Aliased Join) deriving (Eq, Show) -- | Get FieldSource from a TAFExp type table aggregate field fromTableExpFieldG :: -- TODO: Convert function to be similar to Nodes function (Int, (IR.FieldName, IR.TableAggregateFieldG 'MSSQL Void Expression)) -> Maybe (ReaderT EntityAlias FromIr (Int, Projection)) fromTableExpFieldG = \case (index, (IR.FieldName name, IR.TAFExp text)) -> Just $ pure $ ( index, fieldSourceProjections $ ExpressionFieldSource Aliased { aliasedThing = TSQL.ValueExpression (ODBC.TextValue text), aliasedAlias = name } ) _ -> Nothing fromTableAggFieldG :: (Int, (IR.FieldName, IR.TableAggregateFieldG 'MSSQL Void Expression)) -> Maybe (Int, (IR.FieldName, [Projection])) fromTableAggFieldG = \case (index, (fieldName, IR.TAFAgg (aggregateFields :: [(IR.FieldName, IR.AggregateField 'MSSQL)]))) -> Just $ let aggregates = aggregateFields <&> \(fieldName', aggregateField) -> fromAggregateField (IR.getFieldNameTxt fieldName') aggregateField in (index, (fieldName, aggregates)) _ -> Nothing fromTableNodesFieldG :: Map TableName EntityAlias -> IR.StringifyNumbers -> (Int, (IR.FieldName, IR.TableAggregateFieldG 'MSSQL Void Expression)) -> Maybe (ReaderT EntityAlias FromIr (Int, (IR.FieldName, [FieldSource]))) fromTableNodesFieldG argsExistingJoins stringifyNumbers = \case (index, (fieldName, IR.TAFNodes () (annFieldsG :: [(IR.FieldName, IR.AnnFieldG 'MSSQL Void Expression)]))) -> Just do fieldSources' <- fromAnnFieldsG argsExistingJoins stringifyNumbers `traverse` annFieldsG pure (index, (fieldName, fieldSources')) _ -> Nothing fromAggregateField :: Text -> IR.AggregateField 'MSSQL -> Projection fromAggregateField alias aggregateField = case aggregateField of IR.AFExp text -> AggregateProjection $ Aliased (TextAggregate text) alias IR.AFCount countType -> AggregateProjection . flip Aliased alias . CountAggregate $ case countType of StarCountable -> StarCountable NonNullFieldCountable name -> NonNullFieldCountable $ columnFieldAggEntity name DistinctCountable name -> DistinctCountable $ columnFieldAggEntity name IR.AFOp IR.AggregateOp {_aoOp = op, _aoFields = fields} -> let projections :: [Projection] = fields <&> \(fieldName, columnField) -> case columnField of IR.CFCol column _columnType -> let fname = columnFieldAggEntity column in AggregateProjection $ Aliased (OpAggregate op [ColumnExpression fname]) (IR.getFieldNameTxt fieldName) IR.CFExp text -> ExpressionProjection $ Aliased (ValueExpression (ODBC.TextValue text)) (IR.getFieldNameTxt fieldName) in ExpressionProjection $ flip Aliased alias $ safeJsonQueryExpression JsonSingleton $ SelectExpression $ emptySelect { selectProjections = projections, selectFor = JsonFor $ ForJson JsonSingleton NoRoot } where columnFieldAggEntity col = columnNameToFieldName col $ EntityAlias aggSubselectName -- | The main sources of fields, either constants, fields or via joins. fromAnnFieldsG :: Map TableName EntityAlias -> IR.StringifyNumbers -> (IR.FieldName, IR.AnnFieldG 'MSSQL Void Expression) -> ReaderT EntityAlias FromIr FieldSource fromAnnFieldsG existingJoins stringifyNumbers (IR.FieldName name, field) = case field of IR.AFColumn annColumnField -> do expression <- fromAnnColumnField stringifyNumbers annColumnField pure ( ExpressionFieldSource Aliased {aliasedThing = expression, aliasedAlias = name} ) IR.AFExpression text -> pure ( ExpressionFieldSource Aliased { aliasedThing = TSQL.ValueExpression (ODBC.TextValue text), aliasedAlias = name } ) IR.AFObjectRelation objectRelationSelectG -> fmap ( \aliasedThing -> JoinFieldSource JsonSingleton (Aliased {aliasedThing, aliasedAlias = name}) ) (fromObjectRelationSelectG existingJoins objectRelationSelectG) IR.AFArrayRelation arraySelectG -> fmap ( \aliasedThing -> JoinFieldSource JsonArray (Aliased {aliasedThing, aliasedAlias = name}) ) (fromArraySelectG arraySelectG) -- | Here is where we project a field as a column expression. If -- number stringification is on, then we wrap it in a -- 'ToStringExpression' so that it's casted when being projected. fromAnnColumnField :: IR.StringifyNumbers -> IR.AnnColumnField 'MSSQL Expression -> ReaderT EntityAlias FromIr Expression fromAnnColumnField _stringifyNumbers annColumnField = do fieldName <- fromColumn column -- TODO: Handle stringifying large numbers {-(IR.isScalarColumnWhere isBigNum typ && stringifyNumbers == IR.StringifyNumbers)-} -- for geometry and geography values, the automatic json encoding on sql -- server would fail. So we need to convert it to a format the json encoding -- handles. Ideally we want this representation to be GeoJSON but sql server -- doesn't have any functions to convert to GeoJSON format. So we return it in -- WKT format if typ == (IR.ColumnScalar GeometryType) || typ == (IR.ColumnScalar GeographyType) then pure $ MethodApplicationExpression (ColumnExpression fieldName) MethExpSTAsText else case caseBoolExpMaybe of Nothing -> pure (ColumnExpression fieldName) Just ex -> do ex' <- fromGBoolExp (coerce ex) let nullValue = ValueExpression ODBC.NullValue pure (ConditionalExpression ex' (ColumnExpression fieldName) nullValue) where IR.AnnColumnField { _acfColumn = column, _acfType = typ, _acfAsText = _asText :: Bool, _acfOp = _ :: Maybe (IR.ColumnOp 'MSSQL), -- TODO: What's this? _acfCaseBoolExpression = caseBoolExpMaybe } = annColumnField -- | This is where a field name "foo" is resolved to a fully qualified -- field name [table].[foo]. The table name comes from EntityAlias in -- the ReaderT. fromColumn :: ColumnName -> ReaderT EntityAlias FromIr FieldName fromColumn column = columnNameToFieldName column <$> ask -- entityAlias <- ask -- pure (columnNameToFieldName column entityAlias -- FieldName {fieldName = columnName column, fieldNameEntity = entityAliasText} -- ) fieldSourceProjections :: FieldSource -> Projection fieldSourceProjections = \case ExpressionFieldSource aliasedExpression -> ExpressionProjection aliasedExpression JoinFieldSource cardinality aliasedJoin -> ExpressionProjection ( aliasedJoin { aliasedThing = -- Basically a cast, to ensure that SQL Server won't -- double-encode the JSON but will "pass it through" -- untouched. safeJsonQueryExpression cardinality ( ColumnExpression ( joinAliasToField (joinJoinAlias (aliasedThing aliasedJoin)) ) ) } ) joinAliasToField :: JoinAlias -> FieldName joinAliasToField JoinAlias {..} = FieldName { fieldNameEntity = joinAliasEntity, fieldName = fromMaybe (error "TODO: Eliminate this case. joinAliasToField") joinAliasField } fieldSourceJoin :: FieldSource -> Maybe Join fieldSourceJoin = \case JoinFieldSource _ aliasedJoin -> pure (aliasedThing aliasedJoin) ExpressionFieldSource {} -> Nothing -------------------------------------------------------------------------------- -- Joins fromObjectRelationSelectG :: Map TableName EntityAlias -> IR.ObjectRelationSelectG 'MSSQL Void Expression -> ReaderT EntityAlias FromIr Join fromObjectRelationSelectG existingJoins annRelationSelectG = do eitherAliasOrFrom <- lift (lookupTableFrom existingJoins tableFrom) let entityAlias :: EntityAlias = either id fromAlias eitherAliasOrFrom fieldSources <- local (const entityAlias) (traverse (fromAnnFieldsG mempty IR.LeaveNumbersAlone) fields) let selectProjections = map fieldSourceProjections fieldSources joinJoinAlias <- do fieldName <- lift (fromRelName _aarRelationshipName) alias <- lift (generateAlias (ObjectRelationTemplate fieldName)) pure JoinAlias { joinAliasEntity = alias, joinAliasField = pure jsonFieldName } let selectFor = JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = NoRoot} filterExpression <- local (const entityAlias) (fromGBoolExp tableFilter) case eitherAliasOrFrom of Right selectFrom -> do foreignKeyConditions <- fromMapping selectFrom mapping pure Join { joinJoinAlias, joinSource = JoinSelect emptySelect { selectOrderBy = Nothing, selectTop = NoTop, selectProjections, selectFrom = Just selectFrom, selectJoins = mapMaybe fieldSourceJoin fieldSources, selectWhere = Where (foreignKeyConditions <> [filterExpression]), selectFor, selectOffset = Nothing } } Left _entityAlias -> pure Join { joinJoinAlias, joinSource = JoinReselect Reselect { reselectProjections = selectProjections, reselectFor = selectFor, reselectWhere = Where [filterExpression] } } where IR.AnnObjectSelectG { _aosFields = fields :: IR.AnnFieldsG 'MSSQL Void Expression, _aosTableFrom = tableFrom :: TableName, _aosTableFilter = tableFilter :: IR.AnnBoolExp 'MSSQL Expression } = annObjectSelectG IR.AnnRelationSelectG { _aarRelationshipName, _aarColumnMapping = mapping :: HashMap ColumnName ColumnName, _aarAnnSelect = annObjectSelectG :: IR.AnnObjectSelectG 'MSSQL Void Expression } = annRelationSelectG lookupTableFrom :: Map TableName EntityAlias -> TableName -> FromIr (Either EntityAlias From) lookupTableFrom existingJoins tableFrom = do case M.lookup tableFrom existingJoins of Just entityAlias -> pure (Left entityAlias) Nothing -> fmap Right (fromQualifiedTable tableFrom) fromArraySelectG :: IR.ArraySelectG 'MSSQL Void Expression -> ReaderT EntityAlias FromIr Join fromArraySelectG = \case IR.ASSimple arrayRelationSelectG -> fromArrayRelationSelectG arrayRelationSelectG IR.ASAggregate arrayAggregateSelectG -> fromArrayAggregateSelectG arrayAggregateSelectG fromArrayAggregateSelectG :: IR.AnnRelationSelectG 'MSSQL (IR.AnnAggregateSelectG 'MSSQL Void Expression) -> ReaderT EntityAlias FromIr Join fromArrayAggregateSelectG annRelationSelectG = do fieldName <- lift (fromRelName _aarRelationshipName) joinSelect <- do lhsEntityAlias <- ask -- With this, the foreign key relations are injected automatically -- at the right place by fromSelectAggregate. lift (fromSelectAggregate (pure (lhsEntityAlias, mapping)) annSelectG) alias <- lift (generateAlias (ArrayAggregateTemplate fieldName)) pure Join { joinJoinAlias = JoinAlias { joinAliasEntity = alias, joinAliasField = pure jsonFieldName }, joinSource = JoinSelect joinSelect } where IR.AnnRelationSelectG { _aarRelationshipName, _aarColumnMapping = mapping :: HashMap ColumnName ColumnName, _aarAnnSelect = annSelectG } = annRelationSelectG fromArrayRelationSelectG :: IR.ArrayRelationSelectG 'MSSQL Void Expression -> ReaderT EntityAlias FromIr Join fromArrayRelationSelectG annRelationSelectG = do fieldName <- lift (fromRelName _aarRelationshipName) sel <- lift (fromSelectRows annSelectG) joinSelect <- do foreignKeyConditions <- selectFromMapping sel mapping pure sel {selectWhere = Where foreignKeyConditions <> selectWhere sel} alias <- lift (generateAlias (ArrayRelationTemplate fieldName)) pure Join { joinJoinAlias = JoinAlias { joinAliasEntity = alias, joinAliasField = pure jsonFieldName }, joinSource = JoinSelect joinSelect } where IR.AnnRelationSelectG { _aarRelationshipName, _aarColumnMapping = mapping :: HashMap ColumnName ColumnName, _aarAnnSelect = annSelectG } = annRelationSelectG fromRelName :: IR.RelName -> FromIr Text fromRelName relName = pure (IR.relNameToTxt relName) -- | The context given by the reader is of the previous/parent -- "remote" table. The WHERE that we're generating goes in the child, -- "local" query. The @From@ passed in as argument is the local table. -- -- We should hope to see e.g. "post.category = category.id" for a -- local table of post and a remote table of category. -- -- The left/right columns in @HashMap ColumnName ColumnName@ corresponds -- to the left/right of @select ... join ...@. Therefore left=remote, -- right=local in this context. fromMapping :: From -> HashMap ColumnName ColumnName -> ReaderT EntityAlias FromIr [Expression] fromMapping localFrom = traverse ( \(remoteColumn, localColumn) -> do localFieldName <- local (const (fromAlias localFrom)) (fromColumn localColumn) remoteFieldName <- fromColumn remoteColumn pure ( OpExpression TSQL.EQ' (ColumnExpression localFieldName) (ColumnExpression remoteFieldName) ) ) . HM.toList selectFromMapping :: Select -> HashMap ColumnName ColumnName -> ReaderT EntityAlias FromIr [Expression] selectFromMapping Select {selectFrom = Nothing} = const (pure []) selectFromMapping Select {selectFrom = Just from} = fromMapping from -------------------------------------------------------------------------------- -- Basic SQL expression types fromOpExpG :: Expression -> IR.OpExpG 'MSSQL Expression -> FromIr Expression fromOpExpG expression op = case op of IR.ANISNULL -> pure $ TSQL.IsNullExpression expression IR.ANISNOTNULL -> pure $ TSQL.IsNotNullExpression expression IR.AEQ False val -> pure $ nullableBoolEquality expression val IR.AEQ True val -> pure $ OpExpression TSQL.EQ' expression val IR.ANE False val -> pure $ nullableBoolInequality expression val IR.ANE True val -> pure $ OpExpression TSQL.NEQ' expression val IR.AGT val -> pure $ OpExpression TSQL.GT expression val IR.ALT val -> pure $ OpExpression TSQL.LT expression val IR.AGTE val -> pure $ OpExpression TSQL.GTE expression val IR.ALTE val -> pure $ OpExpression TSQL.LTE expression val IR.AIN val -> pure $ OpExpression TSQL.IN expression val IR.ANIN val -> pure $ OpExpression TSQL.NIN expression val IR.ALIKE val -> pure $ OpExpression TSQL.LIKE expression val IR.ANLIKE val -> pure $ OpExpression TSQL.NLIKE expression val IR.ABackendSpecific o -> case o of ASTContains val -> pure $ TSQL.STOpExpression TSQL.STContains expression val ASTCrosses val -> pure $ TSQL.STOpExpression TSQL.STCrosses expression val ASTEquals val -> pure $ TSQL.STOpExpression TSQL.STEquals expression val ASTIntersects val -> pure $ TSQL.STOpExpression TSQL.STIntersects expression val ASTOverlaps val -> pure $ TSQL.STOpExpression TSQL.STOverlaps expression val ASTTouches val -> pure $ TSQL.STOpExpression TSQL.STTouches expression val ASTWithin val -> pure $ TSQL.STOpExpression TSQL.STWithin expression val -- As of March 2021, only geometry/geography casts are supported IR.ACast _casts -> refute (pure (UnsupportedOpExpG op)) -- mkCastsExp casts -- We do not yet support column names in permissions IR.CEQ _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SEQ lhs $ mkQCol rhsCol IR.CNE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SNE lhs $ mkQCol rhsCol IR.CGT _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SGT lhs $ mkQCol rhsCol IR.CLT _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SLT lhs $ mkQCol rhsCol IR.CGTE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SGTE lhs $ mkQCol rhsCol IR.CLTE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SLTE lhs $ mkQCol rhsCol nullableBoolEquality :: Expression -> Expression -> Expression nullableBoolEquality x y = OrExpression [ OpExpression TSQL.EQ' x y, AndExpression [IsNullExpression x, IsNullExpression y] ] nullableBoolInequality :: Expression -> Expression -> Expression nullableBoolInequality x y = OrExpression [ OpExpression TSQL.NEQ' x y, AndExpression [IsNotNullExpression x, IsNullExpression y] ] -- | Translate a 'GBoolExp' of a 'AnnBoolExpFld', within an 'EntityAlias' context. -- -- It is mutually recursive with 'fromAnnBoolExpFld' and 'fromGExists'. fromGBoolExp :: IR.GBoolExp 'MSSQL (IR.AnnBoolExpFld 'MSSQL Expression) -> ReaderT EntityAlias FromIr Expression fromGBoolExp = \case IR.BoolAnd expressions -> fmap AndExpression (traverse fromGBoolExp expressions) IR.BoolOr expressions -> fmap OrExpression (traverse fromGBoolExp expressions) IR.BoolNot expression -> fmap NotExpression (fromGBoolExp expression) IR.BoolExists gExists -> fromGExists gExists IR.BoolFld expression -> fromAnnBoolExpFld expression where fromGExists :: IR.GExists 'MSSQL (IR.AnnBoolExpFld 'MSSQL Expression) -> ReaderT EntityAlias FromIr Expression fromGExists IR.GExists {_geTable, _geWhere} = do selectFrom <- lift (fromQualifiedTable _geTable) whereExpression <- local (const (fromAlias selectFrom)) (fromGBoolExp _geWhere) pure $ ExistsExpression $ emptySelect { selectOrderBy = Nothing, selectProjections = [ ExpressionProjection ( Aliased { aliasedThing = trueExpression, aliasedAlias = existsFieldName } ) ], selectFrom = Just selectFrom, selectJoins = mempty, selectWhere = Where [whereExpression], selectTop = NoTop, selectFor = NoFor, selectOffset = Nothing } trueExpression :: Expression trueExpression = ValueExpression (ODBC.BoolValue True) -- | A version of @JSON_QUERY(..)@ that returns a proper json literal, rather -- than SQL null, which does not compose properly with @FOR JSON@ clauses. safeJsonQueryExpression :: JsonCardinality -> Expression -> Expression safeJsonQueryExpression expectedType jsonQuery = FunctionApplicationExpression (FunExpISNULL (JsonQueryExpression jsonQuery) jsonTypeExpression) where jsonTypeExpression = case expectedType of JsonSingleton -> nullExpression JsonArray -> emptyArrayExpression nullExpression :: Expression nullExpression = ValueExpression $ ODBC.TextValue "null" emptyArrayExpression :: Expression emptyArrayExpression = ValueExpression $ ODBC.TextValue "[]" -------------------------------------------------------------------------------- -- Constants jsonFieldName :: Text jsonFieldName = "json" aggSubselectName :: Text aggSubselectName = "agg_sub" existsFieldName :: Text existsFieldName = "exists_placeholder" data UnfurledJoin = UnfurledJoin { unfurledJoin :: Join, -- | Recorded if we joined onto an object relation. unfurledObjectTableAlias :: Maybe (TableName, EntityAlias) } deriving (Show) fromAnnotatedOrderByItemG :: IR.AnnotatedOrderByItemG 'MSSQL Expression -> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) OrderBy fromAnnotatedOrderByItemG IR.OrderByItemG {obiType, obiColumn = obiColumn, obiNulls} = do (orderByFieldName, orderByType) <- unfurlAnnotatedOrderByElement obiColumn let orderByNullsOrder = fromMaybe NullsAnyOrder obiNulls orderByOrder = fromMaybe AscOrder obiType pure OrderBy {..} -- | Unfurl the nested set of object relations (tell'd in the writer) -- that are terminated by field name (IR.AOCColumn and -- IR.AOCArrayAggregation). unfurlAnnotatedOrderByElement :: IR.AnnotatedOrderByElement 'MSSQL Expression -> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) (FieldName, Maybe TSQL.ScalarType) unfurlAnnotatedOrderByElement = \case IR.AOCColumn columnInfo -> do fieldName <- lift (fromColumnInfo columnInfo) pure ( fieldName, case IR.ciType columnInfo of IR.ColumnScalar t -> Just t -- Above: It is of interest to us whether the type is -- text/ntext/image. See ToQuery for more explanation. _ -> Nothing ) IR.AOCObjectRelation IR.RelInfo {riMapping = mapping, riRTable = table} annBoolExp annOrderByElementG -> do selectFrom <- lift (lift (fromQualifiedTable table)) joinAliasEntity <- lift (lift (generateAlias (ForOrderAlias (tableNameText table)))) foreignKeyConditions <- lift (fromMapping selectFrom mapping) -- TODO: Because these object relations are re-used by regular -- object mapping queries, this WHERE may be unnecessarily -- restrictive. But I actually don't know from where such an -- expression arises in the source GraphQL syntax. -- -- Worst case scenario, we could put the WHERE in the key of the -- Map in 'argsExistingJoins'. That would guarantee only equal -- selects are re-used. whereExpression <- lift (local (const (fromAlias selectFrom)) (fromGBoolExp annBoolExp)) tell ( pure UnfurledJoin { unfurledJoin = Join { joinSource = JoinSelect emptySelect { selectTop = NoTop, selectProjections = [StarProjection], selectFrom = Just selectFrom, selectJoins = [], selectWhere = Where (foreignKeyConditions <> [whereExpression]), selectFor = NoFor, selectOrderBy = Nothing, selectOffset = Nothing }, joinJoinAlias = JoinAlias {joinAliasEntity, joinAliasField = Nothing} }, unfurledObjectTableAlias = Just (table, EntityAlias joinAliasEntity) } ) local (const (EntityAlias joinAliasEntity)) (unfurlAnnotatedOrderByElement annOrderByElementG) IR.AOCArrayAggregation IR.RelInfo {riMapping = mapping, riRTable = tableName} annBoolExp annAggregateOrderBy -> do selectFrom <- lift (lift (fromQualifiedTable tableName)) let alias = aggFieldName joinAliasEntity <- lift (lift (generateAlias (ForOrderAlias (tableNameText tableName)))) foreignKeyConditions <- lift (fromMapping selectFrom mapping) whereExpression <- lift (local (const (fromAlias selectFrom)) (fromGBoolExp annBoolExp)) aggregate <- lift ( local (const (fromAlias selectFrom)) ( case annAggregateOrderBy of IR.AAOCount -> pure (CountAggregate StarCountable) IR.AAOOp text columnInfo -> do fieldName <- fromColumnInfo columnInfo pure (OpAggregate text (pure (ColumnExpression fieldName))) ) ) tell ( pure ( UnfurledJoin { unfurledJoin = Join { joinSource = JoinSelect emptySelect { selectTop = NoTop, selectProjections = [ AggregateProjection Aliased { aliasedThing = aggregate, aliasedAlias = alias } ], selectFrom = Just selectFrom, selectJoins = [], selectWhere = Where (foreignKeyConditions <> [whereExpression]), selectFor = NoFor, selectOrderBy = Nothing, selectOffset = Nothing }, joinJoinAlias = JoinAlias {joinAliasEntity, joinAliasField = Nothing} }, unfurledObjectTableAlias = Nothing } ) ) pure ( FieldName {fieldNameEntity = joinAliasEntity, fieldName = alias}, Nothing ) tableNameText :: TableName -> Text tableNameText (TableName {tableName}) = tableName fromColumnInfo :: IR.ColumnInfo 'MSSQL -> ReaderT EntityAlias FromIr FieldName fromColumnInfo IR.ColumnInfo {ciColumn = column} = columnNameToFieldName column <$> ask aggFieldName :: Text aggFieldName = "agg"