{-# LANGUAGE ViewPatterns #-} -- | Translate from the DML to the TSql dialect. -- -- We use 'StateT' (newtype 'FromIr') as the base monad for all operations, since -- state is used to mangle names such that the scope of identifiers in the IR is -- preserved in the resulting TSQL. -- -- For the MSSQL backend, a supported subset of the constructs that make -- up its TSQL dialect are represented in the form of data-types in the -- Hasura.Backends.MSSQL.Types module. In this module, we translate from RQL to -- those TSQL types. And in 'ToQuery' we render/serialize/print the TSQL types to -- query-strings that are suitable to be executed on the actual MSSQL database. -- -- In places where a series of transations are scoped under a context, we use -- 'ReaderT'. For example, such translations as pertaining to a table with an -- alias, will require the alias for their translation operations, like qualified -- equality checks under where clauses, etc., perhaps below multiple layers of -- nested function calls. module Hasura.Backends.MSSQL.FromIr ( fromSelectRows, mkSQLSelect, fromRootField, fromSelectAggregate, fromGBoolExp, Error (..), runFromIr, FromIr, jsonFieldName, fromInsert, fromDelete, fromUpdate, toSelectIntoTempTable, ) where import Control.Monad.Validate import Data.HashMap.Strict qualified as HM import Data.Map.Strict (Map) import Data.Map.Strict qualified as M import Data.Proxy import Data.Text qualified as T import Database.ODBC.SQLServer qualified as ODBC import Hasura.Backends.MSSQL.Instances.Types () import Hasura.Backends.MSSQL.Types 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 import Language.GraphQL.Draft.Syntax (unName) -------------------------------------------------------------------------------- -- Types -- | Most of these errors should be checked for legitimacy. data Error = UnsupportedOpExpG (IR.OpExpG 'MSSQL Expression) | FunctionNotSupported | NodesUnsupportedForNow | ConnectionsNotSupported deriving (Show, Eq) -- | The base monad used throughout this module for all conversion -- functions. -- -- It's a Validate, so it'll continue going when it encounters errors -- to accumulate as many as possible. -- -- It also contains a mapping from entity prefixes to counters. So if -- my prefix is "table" then there'll be a counter that lets me -- generate table1, table2, etc. Same for any other prefix needed -- (e.g. names for joins). -- -- A ReaderT is used around this in most of the module too, for -- setting the current entity that a given field name refers to. See -- @fromPGCol@. newtype FromIr a = FromIr { unFromIr :: StateT (Map Text Int) (Validate (NonEmpty Error)) a } deriving (Functor, Applicative, Monad, MonadValidate (NonEmpty Error)) data StringifyNumbers = StringifyNumbers | LeaveNumbersAlone deriving (Eq) -------------------------------------------------------------------------------- -- Runners runFromIr :: FromIr a -> Validate (NonEmpty Error) a runFromIr fromIr = evalStateT (unFromIr fromIr) mempty -------------------------------------------------------------------------------- -- Similar rendition of old API mkSQLSelect :: IR.JsonAggSelect -> IR.AnnSelectG 'MSSQL Void (IR.AnnFieldG 'MSSQL Void) Expression -> FromIr TSQL.Select mkSQLSelect jsonAggSelect annSimpleSel = case jsonAggSelect of IR.JASMultipleRows -> fromSelectRows annSimpleSel IR.JASSingleObject -> fromSelectRows annSimpleSel <&> \sel -> sel { selectFor = JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = NoRoot}, selectTop = Top 1 } -- | Convert from the IR database query into a select. fromRootField :: IR.QueryDB 'MSSQL Void Expression -> FromIr Select fromRootField = \case (IR.QDBSingleRow s) -> mkSQLSelect IR.JASSingleObject s (IR.QDBMultipleRows s) -> mkSQLSelect IR.JASMultipleRows s (IR.QDBAggregation s) -> fromSelectAggregate Nothing s -------------------------------------------------------------------------------- -- Top-level exported functions -- | Top/root-level 'Select'. All descendent/sub-translations are collected to produce a root TSQL.Select. fromSelectRows :: IR.AnnSelectG 'MSSQL Void (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 = num } = annSelectG IR.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm permissionBasedTop = maybe NoTop Top mPermLimit stringifyNumbers = if num then StringifyNumbers else LeaveNumbersAlone 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 = JsonQueryExpression $ 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 Void (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 = (bool LeaveNumbersAlone StringifyNumbers -> 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) data UnfurledJoin = UnfurledJoin { unfurledJoin :: Join, -- | Recorded if we joined onto an object relation. unfurledObjectTableAlias :: Maybe (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 -- | Produce a valid ORDER BY construct, telling about any joins -- needed on the side. 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 pgColumnInfo -> do fieldName <- lift (fromPGColumnInfo pgColumnInfo) pure ( fieldName, case (IR.pgiType pgColumnInfo) 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 pgColumnInfo -> do fieldName <- fromPGColumnInfo pgColumnInfo 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 ) -------------------------------------------------------------------------------- -- Conversion functions tableNameText :: TableName -> Text tableNameText (TableName {tableName}) = tableName -- | This is really the start where you query the base table, -- everything else is joins attached to it. fromQualifiedTable :: TableName -> FromIr From fromQualifiedTable schemadTableName@(TableName {tableName}) = do alias <- generateAlias (TableTemplate tableName) pure ( FromQualifiedTable ( Aliased { aliasedThing = schemadTableName, aliasedAlias = alias } ) ) fromTableName :: TableName -> FromIr EntityAlias fromTableName TableName {tableName} = do alias <- generateAlias (TableTemplate tableName) pure (EntityAlias 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 pgColumnInfo opExpGs -> do expression <- fromColumnInfoForBoolExp pgColumnInfo 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 {pgiColumn = pgCol, pgiType} = do fieldName <- columnNameToFieldName pgCol <$> ask if shouldCastToVarcharMax pgiType -- See function commentary. then pure (CastExpression (ColumnExpression fieldName) "VARCHAR(MAX)") 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 fromPGColumnInfo :: IR.ColumnInfo 'MSSQL -> ReaderT EntityAlias FromIr FieldName fromPGColumnInfo IR.ColumnInfo {pgiColumn = pgCol} = columnNameToFieldName pgCol <$> ask -- entityAlias <- ask -- pure -- (columnNameToFieldName pgCol entityAlias -- FieldName -- {fieldName = PG.getPGColTxt pgCol, fieldNameEntity = entityAliasText}) -------------------------------------------------------------------------------- -- 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 (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 -> 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 names -> NonNullFieldCountable $ fmap columnFieldAggEntity names DistinctCountable names -> DistinctCountable $ fmap columnFieldAggEntity names IR.AFOp IR.AggregateOp {_aoOp = op, _aoFields = fields} -> let projections :: [Projection] = fields <&> \(fieldName, pgColFld) -> case pgColFld of IR.CFCol pgCol _pgType -> let fname = columnFieldAggEntity pgCol 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 $ JsonQueryExpression $ 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 -> 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 (Aliased {aliasedThing, aliasedAlias = name}) ) (fromObjectRelationSelectG existingJoins objectRelationSelectG) IR.AFArrayRelation arraySelectG -> fmap ( \aliasedThing -> JoinFieldSource (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 :: StringifyNumbers -> IR.AnnColumnField 'MSSQL Expression -> ReaderT EntityAlias FromIr Expression fromAnnColumnField _stringifyNumbers annColumnField = do fieldName <- fromPGCol pgCol -- TODO: Handle stringifying large numbers {-(IR.isScalarColumnWhere PG.isBigNum typ && stringifyNumbers == 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 $ MethodExpression (ColumnExpression fieldName) "STAsText" [] 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 = pgCol, _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. fromPGCol :: ColumnName -> ReaderT EntityAlias FromIr FieldName fromPGCol pgCol = columnNameToFieldName pgCol <$> ask -- entityAlias <- ask -- pure (columnNameToFieldName pgCol entityAlias -- FieldName {fieldName = PG.getPGColTxt pgCol, fieldNameEntity = entityAliasText} -- ) fieldSourceProjections :: FieldSource -> Projection fieldSourceProjections = \case ExpressionFieldSource aliasedExpression -> ExpressionProjection aliasedExpression JoinFieldSource aliasedJoin -> ExpressionProjection ( aliasedJoin { aliasedThing = -- Basically a cast, to ensure that SQL Server won't -- double-encode the JSON but will "pass it through" -- untouched. JsonQueryExpression ( 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 {-PG.QualifiedTable-} 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 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 {-PG.QualifiedTable-}, _aosTableFilter = tableFilter :: IR.AnnBoolExp 'MSSQL Expression } = annObjectSelectG IR.AnnRelationSelectG { aarRelationshipName, aarColumnMapping = mapping :: HashMap ColumnName ColumnName, -- PG.PGCol PG.PGCol aarAnnSelect = annObjectSelectG :: IR.AnnObjectSelectG 'MSSQL Void Expression } = annRelationSelectG lookupTableFrom :: Map TableName {-PG.QualifiedTable-} EntityAlias -> {-PG.QualifiedTable-} 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, -- PG.PGCol PG.PGCol 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 PG.PGCol PG.PGCol@ corresponds -- to the left/right of @select ... join ...@. Therefore left=remote, -- right=local in this context. fromMapping :: From -> HashMap ColumnName ColumnName -> -- PG.PGCol PG.PGCol ReaderT EntityAlias FromIr [Expression] fromMapping localFrom = traverse ( \(remotePgCol, localPgCol) -> do localFieldName <- local (const (fromAlias localFrom)) (fromPGCol localPgCol) remoteFieldName <- fromPGCol remotePgCol 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 } -------------------------------------------------------------------------------- -- Insert fromInsert :: IR.AnnInsert 'MSSQL Void Expression -> Insert fromInsert IR.AnnInsert {..} = let IR.AnnIns {..} = _aiData insertRows = normalizeInsertRows _aiData $ map (IR.getInsertColumns) _aiInsObj insertColumnNames = maybe [] (map fst) $ listToMaybe insertRows insertValues = map (Values . map snd) insertRows primaryKeyColumns = map OutputColumn $ _mssqlPrimaryKeyColumns _aiBackendInsert in Insert _aiTableName insertColumnNames (Output Inserted primaryKeyColumns) insertValues -- | Normalize a row by adding missing columns with 'DEFAULT' value and sort by column name to make sure -- all rows are consistent in column values and order. -- -- Example: A table "author" is defined as -- -- CREATE TABLE author ([id] INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL, age INTEGER) -- -- Consider the following mutation; -- -- mutation { -- insert_author( -- objects: [{id: 1, name: "Foo", age: 21}, {id: 2, name: "Bar"}] -- ){ -- affected_rows -- } -- } -- -- We consider 'DEFAULT' value for "age" column which is missing in second insert row. The INSERT statement look like -- -- INSERT INTO author (id, name, age) OUTPUT INSERTED.id VALUES (1, 'Foo', 21), (2, 'Bar', DEFAULT) normalizeInsertRows :: IR.AnnIns 'MSSQL [] Expression -> [[(Column 'MSSQL, Expression)]] -> [[(Column 'MSSQL, Expression)]] normalizeInsertRows IR.AnnIns {..} insertRows = let isIdentityColumn column = IR.pgiColumn column `elem` _mssqlIdentityColumns _aiBackendInsert allColumnsWithDefaultValue = -- DEFAULT or NULL are not allowed as explicit identity values. map ((,DefaultExpression) . IR.pgiColumn) $ filter (not . isIdentityColumn) _aiTableCols addMissingColumns insertRow = HM.toList $ HM.fromList insertRow `HM.union` HM.fromList allColumnsWithDefaultValue sortByColumn = sortBy (\l r -> compare (fst l) (fst r)) in map (sortByColumn . addMissingColumns) insertRows -------------------------------------------------------------------------------- -- Delete -- | Convert IR AST representing delete into MSSQL AST representing a delete statement fromDelete :: IR.AnnDel 'MSSQL -> FromIr Delete fromDelete (IR.AnnDel tableName (permFilter, whereClause) _ allColumns) = do tableAlias <- fromTableName tableName runReaderT ( do permissionsFilter <- fromGBoolExp permFilter whereExpression <- fromGBoolExp whereClause let columnNames = map (ColumnName . unName . IR.pgiName) allColumns pure Delete { deleteTable = Aliased { aliasedAlias = entityAliasText tableAlias, aliasedThing = tableName }, deleteOutput = Output Deleted (map OutputColumn columnNames), deleteTempTable = TempTable tempTableNameDeleted columnNames, deleteWhere = Where [permissionsFilter, whereExpression] } ) tableAlias -- | Convert IR AST representing update into MSSQL AST representing an update statement fromUpdate :: IR.AnnotatedUpdate 'MSSQL -> FromIr Update fromUpdate (IR.AnnotatedUpdateG tableName (permFilter, whereClause) _ backendUpdate _ allColumns) = do tableAlias <- fromTableName tableName runReaderT ( do permissionsFilter <- fromGBoolExp permFilter whereExpression <- fromGBoolExp whereClause let columnNames = map (ColumnName . unName . IR.pgiName) allColumns pure Update { updateTable = Aliased { aliasedAlias = entityAliasText tableAlias, aliasedThing = tableName }, updateSet = updateOperations backendUpdate, updateOutput = Output Inserted (map OutputColumn columnNames), updateTempTable = TempTable tempTableNameUpdated columnNames, updateWhere = Where [permissionsFilter, whereExpression] } ) tableAlias -- | Create a temporary table with the same schema as the given table. toSelectIntoTempTable :: TempTableName -> TableName -> [IR.ColumnInfo 'MSSQL] -> SelectIntoTempTable toSelectIntoTempTable tempTableName fromTable allColumns = do SelectIntoTempTable { sittTempTableName = tempTableName, sittColumns = map columnInfoToUnifiedColumn allColumns, sittFromTableName = fromTable } -- | Extracts the type and column name of a ColumnInfo columnInfoToUnifiedColumn :: IR.ColumnInfo 'MSSQL -> UnifiedColumn columnInfoToUnifiedColumn colInfo = case IR.pgiType colInfo of IR.ColumnScalar t -> UnifiedColumn { name = unName $ IR.pgiName colInfo, type' = t } -- Enum values are represented as text value so they will always be of type text IR.ColumnEnumReference {} -> UnifiedColumn { name = unName $ IR.pgiName colInfo, type' = TextType } -------------------------------------------------------------------------------- -- Misc combinators trueExpression :: Expression trueExpression = ValueExpression (ODBC.BoolValue True) -------------------------------------------------------------------------------- -- Constants jsonFieldName :: Text jsonFieldName = "json" aggFieldName :: Text aggFieldName = "agg" aggSubselectName :: Text aggSubselectName = "agg_sub" existsFieldName :: Text existsFieldName = "exists_placeholder" -------------------------------------------------------------------------------- -- Name generation data NameTemplate = ArrayRelationTemplate Text | ArrayAggregateTemplate Text | ObjectRelationTemplate Text | TableTemplate Text | ForOrderAlias Text -- | Generate an alias for a given entity to remove ambiguity and naming -- conflicts between scopes at the TSQL level. Keeps track of the increments for -- the alias index in the 'StateT' generateAlias :: NameTemplate -> FromIr Text generateAlias template = do FromIr (modify' (M.insertWith (+) prefix start)) i <- FromIr get pure (prefix <> tshow (fromMaybe start (M.lookup prefix i))) where start = 1 prefix = T.take 20 rendered rendered = case template of ArrayRelationTemplate sample -> "ar_" <> sample ArrayAggregateTemplate sample -> "aa_" <> sample ObjectRelationTemplate sample -> "or_" <> sample TableTemplate sample -> "t_" <> sample ForOrderAlias sample -> "order_" <> sample fromAlias :: From -> EntityAlias fromAlias (FromQualifiedTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias fromAlias (FromOpenJson Aliased {aliasedAlias}) = EntityAlias aliasedAlias fromAlias (FromSelect Aliased {aliasedAlias}) = EntityAlias aliasedAlias fromAlias (FromIdentifier identifier) = EntityAlias identifier fromAlias (FromTempTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias columnNameToFieldName :: ColumnName -> EntityAlias -> FieldName columnNameToFieldName (ColumnName fieldName) EntityAlias {entityAliasText = fieldNameEntity} = FieldName {fieldName, fieldNameEntity}