graphql-engine/server/src-lib/Hasura/Backends/MSSQL/FromIr.hs
Antoine Leblanc 9a8a211367 server: remove XDistinct, cleanup table arguments
https://github.com/hasura/graphql-engine-mono/pull/1028

GitOrigin-RevId: dae3d46097520f6838b7e95cdda1ab8d53dc9700
2021-06-15 15:54:12 +00:00

979 lines
38 KiB
Haskell

-- | Translate from the DML to the TSql dialect.
module Hasura.Backends.MSSQL.FromIr
( fromSelectRows
, mkSQLSelect
, fromRootField
, fromSelectAggregate
, fromAnnBoolExp
, Error(..)
, runFromIr
, FromIr
, jsonFieldName
, fromDelete
) where
import Hasura.Prelude
import qualified Data.HashMap.Strict as HM
import qualified Data.Map.Strict as M
import qualified Data.Text as T
import qualified Database.ODBC.SQLServer as ODBC
import Control.Monad.Validate
import Data.Map.Strict (Map)
import Data.Proxy
import qualified Hasura.RQL.IR as IR
import qualified Hasura.RQL.Types.Column as IR
import qualified Hasura.RQL.Types.Common as IR
import qualified Hasura.RQL.Types.Relationship as IR
import Hasura.Backends.MSSQL.Instances.Types ()
import Hasura.Backends.MSSQL.Types as TSQL
import Hasura.SQL.Backend
--------------------------------------------------------------------------------
-- 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 (IR.AnnFieldsG 'MSSQL Expression) 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 Expression -> FromIr Select
fromRootField =
\case
(IR.QDBSingleRow s) -> mkSQLSelect IR.JASSingleObject s
(IR.QDBMultipleRows s) -> mkSQLSelect IR.JASMultipleRows s
(IR.QDBAggregation s) -> fromSelectAggregate s
(IR.QDBConnection _) -> refute $ pure ConnectionsNotSupported
--------------------------------------------------------------------------------
-- Top-level exported functions
fromSelectRows :: IR.AnnSelectG 'MSSQL (IR.AnnFieldsG 'MSSQL Expression) Expression -> FromIr TSQL.Select
fromSelectRows annSelectG = do
selectFrom <-
case from of
IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject
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 (fromAnnBoolExp permFilter) (fromAlias selectFrom)
let selectProjections =
concatMap (toList . fieldSourceProjections) fieldSources
pure
Select
{ 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
fromSelectAggregate ::
IR.AnnSelectG 'MSSQL [(IR.FieldName, IR.TableAggregateFieldG 'MSSQL Expression)] Expression
-> FromIr TSQL.Select
fromSelectAggregate annSelectG = do
selectFrom <-
case from of
IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject
IR.FromFunction {} -> refute $ pure FunctionNotSupported
fieldSources <-
runReaderT (traverse fromTableAggregateFieldG fields) (fromAlias selectFrom)
filterExpression <-
runReaderT (fromAnnBoolExp permFilter) (fromAlias selectFrom)
Args { argsOrderBy
, argsWhere
, argsJoins
, argsTop
, argsDistinct = Proxy
, argsOffset
} <- runReaderT (fromSelectArgsG args) (fromAlias selectFrom)
let selectProjections =
concatMap (toList . fieldSourceProjections) fieldSources
pure
Select
{ selectProjections
, selectTop = permissionBasedTop <> argsTop
, selectFrom = Just selectFrom
, selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources
, selectWhere = argsWhere <> Where [filterExpression]
, selectFor =
JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = Root "aggregate"}
, selectOrderBy = argsOrderBy
, selectOffset = argsOffset
}
where
IR.AnnSelectG { _asnFields = fields
, _asnFrom = from
, _asnPerm = perm
, _asnArgs = args
, _asnStrfyNum = _num -- TODO: Do we ignore this for aggregates?
} = annSelectG
IR.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm
permissionBasedTop = maybe NoTop Top mPermLimit
--------------------------------------------------------------------------------
-- 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
, unfurledObjectTableAlias :: Maybe (TableName, EntityAlias)
-- ^ Recorded if we joined onto an object relation.
} 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) . fromAnnBoolExp) 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 fromAnnOrderByItemG (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.
fromAnnOrderByItemG ::
IR.AnnOrderByItemG 'MSSQL Expression -> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) OrderBy
fromAnnOrderByItemG IR.OrderByItemG {obiType, obiColumn = obiColumn, obiNulls} = do
(orderByFieldName, orderByType) <- unfurlAnnOrderByElement 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).
unfurlAnnOrderByElement
:: IR.AnnOrderByElement 'MSSQL Expression
-> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) (FieldName, Maybe TSQL.ScalarType)
unfurlAnnOrderByElement =
\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 (generateEntityAlias (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)) (fromAnnBoolExp annBoolExp))
tell
(pure
UnfurledJoin
{ unfurledJoin =
Join
{ joinSource =
JoinSelect
Select
{ 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))
(unfurlAnnOrderByElement annOrderByElementG)
IR.AOCArrayAggregation IR.RelInfo {riMapping = mapping, riRTable = tableName} annBoolExp annAggregateOrderBy -> do
selectFrom <- lift (lift (fromQualifiedTable tableName))
let alias = aggFieldName
joinAliasEntity <-
lift (lift (generateEntityAlias (ForOrderAlias (tableNameText tableName))))
foreignKeyConditions <- lift (fromMapping selectFrom mapping)
whereExpression <-
lift (local (const (fromAlias selectFrom)) (fromAnnBoolExp 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
Select
{ 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 :: {-PG.QualifiedObject-} TableName -> Text
tableNameText (TableName {tableName}) = tableName
-- tableNameText qualifiedObject = qname
-- where
-- PG.QualifiedObject {qName = PG.TableName qname} = qualifiedObject
-- | 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 <- generateEntityAlias (TableTemplate tableName)
pure
(FromQualifiedTable
(Aliased
{ aliasedThing =
schemadTableName {-TableName {tableName = qname, tableNameSchema = schemaName}-}
, aliasedAlias = alias
}))
-- where
-- PG.QualifiedObject { qSchema = PG.SchemaName schemaName
-- -- TODO: Consider many x.y.z. in schema name.
-- , qName = PG.TableName qname
-- } = qualifiedObject
fromTableName :: TableName -> FromIr EntityAlias
fromTableName TableName{tableName} = do
alias <- generateEntityAlias (TableTemplate tableName)
pure (EntityAlias alias)
fromAnnBoolExp ::
IR.GBoolExp 'MSSQL (IR.AnnBoolExpFld 'MSSQL Expression)
-> ReaderT EntityAlias FromIr Expression
fromAnnBoolExp = traverse fromAnnBoolExpFld >=> fromGBoolExp
fromAnnBoolExpFld ::
IR.AnnBoolExpFld 'MSSQL Expression -> ReaderT EntityAlias FromIr Expression
fromAnnBoolExpFld =
\case
IR.AVCol pgColumnInfo opExpGs -> do
expression <- fromColumnInfoForBoolExp pgColumnInfo
expressions <- traverse (lift . fromOpExpG expression) opExpGs
pure (AndExpression expressions)
IR.AVRel IR.RelInfo {riMapping = mapping, riRTable = table} annBoolExp -> do
selectFrom <- lift (fromQualifiedTable table)
foreignKeyConditions <- fromMapping selectFrom mapping
whereExpression <-
local (const (fromAlias selectFrom)) (fromAnnBoolExp annBoolExp)
pure
(ExistsExpression
Select
{ 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})
fromGExists :: IR.GExists 'MSSQL Expression -> ReaderT EntityAlias FromIr Select
fromGExists IR.GExists {_geTable, _geWhere} = do
selectFrom <- lift (fromQualifiedTable _geTable)
whereExpression <-
local (const (fromAlias selectFrom)) (fromGBoolExp _geWhere)
pure
Select
{ selectOrderBy = Nothing
, selectProjections =
[ ExpressionProjection
(Aliased
{ aliasedThing = trueExpression
, aliasedAlias = existsFieldName
})
]
, selectFrom = Just selectFrom
, selectJoins = mempty
, selectWhere = Where [whereExpression]
, selectTop = NoTop
, selectFor = NoFor
, selectOffset = Nothing
}
--------------------------------------------------------------------------------
-- 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)
| AggregateFieldSource [Aliased Aggregate]
deriving (Eq, Show)
fromTableAggregateFieldG ::
(IR.FieldName, IR.TableAggregateFieldG 'MSSQL Expression) -> ReaderT EntityAlias FromIr FieldSource
fromTableAggregateFieldG (IR.FieldName name, field) =
case field of
IR.TAFAgg (aggregateFields :: [(IR.FieldName, IR.AggregateField 'MSSQL)]) -> do
aggregates <-
for aggregateFields \(fieldName, aggregateField) ->
fromAggregateField aggregateField <&> \aliasedThing ->
Aliased {aliasedAlias = IR.getFieldNameTxt fieldName, ..}
pure (AggregateFieldSource aggregates)
IR.TAFExp text ->
pure
(ExpressionFieldSource
Aliased
{ aliasedThing = TSQL.ValueExpression (ODBC.TextValue text)
, aliasedAlias = name
})
IR.TAFNodes {} ->
refute (pure NodesUnsupportedForNow)
fromAggregateField :: IR.AggregateField 'MSSQL -> ReaderT EntityAlias FromIr Aggregate
fromAggregateField aggregateField =
case aggregateField of
IR.AFExp text -> pure (TextAggregate text)
IR.AFCount countType -> CountAggregate <$> case countType of
StarCountable -> pure StarCountable
NonNullFieldCountable names -> NonNullFieldCountable <$> traverse fromPGCol names
DistinctCountable names -> DistinctCountable <$> traverse fromPGCol names
-- fmap
-- CountAggregate
-- (pure countType
-- case countType of
-- PG.CTStar -> pure StarCountable
-- PG.CTSimple fields ->
-- case nonEmpty fields of
-- Nothing -> refute (pure MalformedAgg)
-- Just fields' -> do
-- fields'' <- traverse fromPGCol fields'
-- pure (NonNullFieldCountable fields'')
-- PG.CTDistinct fields ->
-- case nonEmpty fields of
-- Nothing -> refute (pure MalformedAgg)
-- Just fields' -> do
-- fields'' <- traverse fromPGCol fields'
-- pure (DistinctCountable fields''))
IR.AFOp IR.AggregateOp {_aoOp = op, _aoFields = fields} -> do
args <- for fields \(_fieldName, pgColFld) ->
case pgColFld of
IR.CFCol pgCol _pgType -> fmap ColumnExpression (fromPGCol pgCol)
IR.CFExp text -> pure (ValueExpression (ODBC.TextValue text))
pure (OpAggregate op args)
-- | The main sources of fields, either constants, fields or via joins.
fromAnnFieldsG ::
Map TableName EntityAlias
-> StringifyNumbers
-> (IR.FieldName, IR.AnnFieldG 'MSSQL 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)
-- this will be gone once the code which collects remote joins from the IR
-- emits a modified IR where remote relationships can't be reached
IR.AFRemote _ ->
pure
(ExpressionFieldSource
Aliased
{ aliasedThing = TSQL.ValueExpression
(ODBC.TextValue "null: remote field selected")
, aliasedAlias = name
})
-- | 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 pure (ColumnExpression fieldName)
where
IR.AnnColumnField { _acfInfo = IR.ColumnInfo{pgiColumn=pgCol,pgiType=typ}
, _acfAsText = _asText :: Bool
, _acfOp = _ :: Maybe (IR.ColumnOp 'MSSQL) -- TODO: What's this?
} = 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 ->
pure (ExpressionProjection aliasedExpression)
JoinFieldSource aliasedJoin ->
pure
(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))))
}))
AggregateFieldSource aggregates -> fmap AggregateProjection aggregates
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
AggregateFieldSource {} -> Nothing
--------------------------------------------------------------------------------
-- Joins
fromObjectRelationSelectG ::
Map TableName {-PG.QualifiedTable-} EntityAlias
-> IR.ObjectRelationSelectG 'MSSQL 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 =
concatMap (toList . fieldSourceProjections) fieldSources
joinJoinAlias <-
do fieldName <- lift (fromRelName aarRelationshipName)
alias <- lift (generateEntityAlias (ObjectRelationTemplate fieldName))
pure
JoinAlias
{joinAliasEntity = alias, joinAliasField = pure jsonFieldName}
let selectFor =
JsonFor ForJson {jsonCardinality = JsonSingleton, jsonRoot = NoRoot}
filterExpression <- local (const entityAlias) (fromAnnBoolExp tableFilter)
case eitherAliasOrFrom of
Right selectFrom -> do
foreignKeyConditions <- fromMapping selectFrom mapping
pure
Join
{ joinJoinAlias
, joinSource =
JoinSelect
Select
{ 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 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 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 Expression -> ReaderT EntityAlias FromIr Join
fromArraySelectG =
\case
IR.ASSimple arrayRelationSelectG ->
fromArrayRelationSelectG arrayRelationSelectG
IR.ASAggregate arrayAggregateSelectG ->
fromArrayAggregateSelectG arrayAggregateSelectG
fromArrayAggregateSelectG ::
IR.AnnRelationSelectG 'MSSQL (IR.AnnAggregateSelectG 'MSSQL Expression)
-> ReaderT EntityAlias FromIr Join
fromArrayAggregateSelectG annRelationSelectG = do
fieldName <- lift (fromRelName aarRelationshipName)
sel <- lift (fromSelectAggregate annSelectG)
joinSelect <-
do foreignKeyConditions <- selectFromMapping sel mapping
pure
sel {selectWhere = Where foreignKeyConditions <> selectWhere sel}
alias <- lift (generateEntityAlias (ArrayAggregateTemplate 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
fromArrayRelationSelectG :: IR.ArrayRelationSelectG 'MSSQL 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 (generateEntityAlias (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]
]
fromGBoolExp :: IR.GBoolExp '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 -> fmap ExistsExpression (fromGExists gExists)
IR.BoolFld expression -> pure expression
--------------------------------------------------------------------------------
-- Delete
fromDelete :: IR.AnnDel 'MSSQL -> FromIr Delete
fromDelete (IR.AnnDel tableName (permFilter, whereClause) _ _) = do
tableAlias <- fromTableName tableName
runReaderT
(do permissionsFilter <- fromAnnBoolExp permFilter
whereExpression <- fromAnnBoolExp whereClause
pure
Delete
{ deleteTable =
Aliased
{ aliasedAlias = entityAliasText tableAlias
, aliasedThing = tableName
}
, deleteWhere = Where [permissionsFilter, whereExpression]
})
tableAlias
--------------------------------------------------------------------------------
-- Misc combinators
trueExpression :: Expression
trueExpression = ValueExpression (ODBC.BoolValue True)
--------------------------------------------------------------------------------
-- Constants
jsonFieldName :: Text
jsonFieldName = "json"
aggFieldName :: Text
aggFieldName = "agg"
existsFieldName :: Text
existsFieldName = "exists_placeholder"
--------------------------------------------------------------------------------
-- Name generation
data NameTemplate
= ArrayRelationTemplate Text
| ArrayAggregateTemplate Text
| ObjectRelationTemplate Text
| TableTemplate Text
| ForOrderAlias Text
generateEntityAlias :: NameTemplate -> FromIr Text
generateEntityAlias 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
columnNameToFieldName :: ColumnName -> EntityAlias -> FieldName
columnNameToFieldName (ColumnName fieldName) EntityAlias {entityAliasText = fieldNameEntity} =
FieldName {fieldName, fieldNameEntity}