graphql-engine/server/src-lib/Hasura/Backends/MySQL/FromIr.hs

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-- | Translate from the DML to the MySQL dialect.
module Hasura.Backends.MySQL.FromIr
( fromSelectRows,
mkSQLSelect,
fromRootField,
FromIr,
Error (..),
runFromIr,
)
where
import Control.Monad.Validate
import Data.HashMap.Strict qualified as HM
import Data.HashSet.InsOrd qualified as OSet
import Data.Map.Strict (Map)
import Data.Map.Strict qualified as M
import Data.Proxy
import Data.Text qualified as T
import Database.MySQL.Base.Types qualified as MySQL
import Hasura.Backends.MySQL.Instances.Types ()
import Hasura.Backends.MySQL.Types
import Hasura.Prelude hiding (GT)
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
data FieldSource
= ExpressionFieldSource (Aliased Expression)
| JoinFieldSource (Aliased Join)
| AggregateFieldSource [Aliased Aggregate]
deriving (Eq, Show)
-- | Most of these errors should be checked for legitimacy.
data Error
= UnsupportedOpExpG (IR.OpExpG 'MySQL Expression)
| IdentifierNotSupported
| 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
-- @fromColumn@.
newtype FromIr a = FromIr
{ unFromIr :: StateT (Map Text Int) (Validate (NonEmpty Error)) a
}
deriving (Functor, Applicative, Monad, MonadValidate (NonEmpty Error))
--------------------------------------------------------------------------------
-- Runners
runFromIr :: FromIr a -> Validate (NonEmpty Error) a
runFromIr fromIr = evalStateT (unFromIr fromIr) mempty
data NameTemplate
= ArrayRelationTemplate Text
| ArrayAggregateTemplate Text
| ObjectRelationTemplate Text
| TableTemplate Text
| ForOrderAlias Text
| IndexTemplate
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
IndexTemplate -> "idx_"
-- | 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 {name}) = do
alias <- generateEntityAlias (TableTemplate name)
pure
( FromQualifiedTable
( Aliased
{ aliasedThing =
schemadTableName,
aliasedAlias = alias
}
)
)
fromAlias :: From -> EntityAlias
fromAlias (FromQualifiedTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias
fromAlias (FromSelect Aliased {aliasedAlias}) = EntityAlias aliasedAlias
trueExpression :: Expression
trueExpression = ValueExpression (BitValue True)
existsFieldName :: Text
existsFieldName = "exists_placeholder"
fromGExists :: IR.GExists 'MySQL 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 =
OSet.fromList
[ ExpressionProjection
( Aliased
{ aliasedThing = trueExpression,
aliasedAlias = existsFieldName
}
)
],
selectFrom = selectFrom,
selectGroupBy = [],
selectJoins = mempty,
selectWhere = Where [whereExpression],
selectSqlTop = NoTop,
selectSqlOffset = Nothing,
selectFinalWantedFields = Nothing
}
fromGBoolExp :: IR.GBoolExp 'MySQL Expression -> ReaderT EntityAlias FromIr Expression
fromGBoolExp = do
\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
fromAnnBoolExp ::
IR.GBoolExp 'MySQL (IR.AnnBoolExpFld 'MySQL Expression) ->
ReaderT EntityAlias FromIr Expression
fromAnnBoolExp boolExp = do
fields <- traverse fromAnnBoolExpFld boolExp
fromGBoolExp fields
-- | 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 'MySQL -> ReaderT EntityAlias FromIr Expression
fromColumnInfoForBoolExp IR.ColumnInfo {ciColumn = column, ciType = _ciType} = do
fieldName <- columnNameToFieldName column <$> ask
pure (ColumnExpression fieldName)
fromAnnBoolExpFld ::
IR.AnnBoolExpFld 'MySQL 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)) (fromAnnBoolExp annBoolExp)
pure
( ExistsExpression
Select
{ selectOrderBy = Nothing,
selectProjections =
OSet.fromList
[ ExpressionProjection
( Aliased
{ aliasedThing = trueExpression,
aliasedAlias = existsFieldName
}
)
],
selectFrom = selectFrom,
selectGroupBy = [],
selectJoins = mempty,
selectWhere = Where (foreignKeyConditions <> [whereExpression]),
selectSqlTop = NoTop,
selectSqlOffset = Nothing,
selectFinalWantedFields = Nothing
}
)
-- | 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 Column Column@ corresponds
-- to the left/right of @select ... join ...@. Therefore left=remote,
-- right=local in this context.
fromMapping ::
From ->
HashMap Column Column ->
ReaderT EntityAlias FromIr [Expression]
fromMapping localFrom = traverse columnsToEqs . HM.toList
where
columnsToEqs (remoteColumn, localColumn) = do
localFieldName <- local (const (fromAlias localFrom)) (fromColumn localColumn)
remoteFieldName <- fromColumn remoteColumn
pure
( OpExpression
EQ'
(ColumnExpression localFieldName)
(ColumnExpression remoteFieldName)
)
fromColumn :: Column -> ReaderT EntityAlias FromIr FieldName
fromColumn column = columnNameToFieldName column <$> ask
columnNameToFieldName :: Column -> EntityAlias -> FieldName
columnNameToFieldName (Column fieldName) EntityAlias {entityAliasText = fieldNameEntity} =
FieldName {fName = fieldName, fNameEntity = fieldNameEntity}
fromOpExpG :: Expression -> IR.OpExpG 'MySQL Expression -> FromIr Expression
fromOpExpG expression op =
case op of
IR.AEQ True val -> do
pure $ OpExpression EQ' expression val
_ -> refute (pure (UnsupportedOpExpG op))
data Args = Args
{ argsWhere :: Where,
argsOrderBy :: Maybe (NonEmpty OrderBy),
argsJoins :: [Join],
argsTop :: Top,
argsOffset :: Maybe Int,
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)
fromColumnInfo :: IR.ColumnInfo 'MySQL -> ReaderT EntityAlias FromIr FieldName
fromColumnInfo IR.ColumnInfo {ciColumn = column} =
columnNameToFieldName column <$> ask
tableNameText :: TableName -> Text
tableNameText (TableName {name}) = name
aggFieldName :: Text
aggFieldName = "agg"
-- | 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.AnnotatedOrderByElement 'MySQL Expression ->
WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) (FieldName, Maybe ScalarType)
unfurlAnnOrderByElement =
\case
IR.AOCColumn columnInfo -> do
fieldName <- lift (fromColumnInfo columnInfo)
pure
( fieldName,
case IR.ciType columnInfo of
IR.ColumnScalar t -> Just t
_ -> Nothing
)
IR.AOCObjectRelation IR.RelInfo {riRTable = table} annBoolExp annOrderByElementG -> do
selectFrom <- lift (lift (fromQualifiedTable table))
joinAliasEntity <-
lift (lift (generateEntityAlias (ForOrderAlias (tableNameText table))))
whereExpression <-
lift (local (const (fromAlias selectFrom)) (fromAnnBoolExp annBoolExp))
tell
( pure
UnfurledJoin
{ unfurledJoin =
Join
{ joinSelect =
Select
{ selectProjections = OSet.fromList [StarProjection],
selectSqlTop = NoTop,
selectSqlOffset = Nothing,
selectFrom = selectFrom,
selectJoins = [],
selectWhere =
Where [whereExpression],
selectOrderBy = Nothing,
selectFinalWantedFields = Nothing,
selectGroupBy = []
},
joinRightTable = fromAlias selectFrom,
joinType = OnlessJoin,
joinFieldName = name table,
joinTop = NoTop,
joinOffset = 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 columnInfo -> do
fieldName <- fromColumnInfo columnInfo
pure (OpAggregate text (pure (ColumnExpression fieldName)))
)
)
tell
( pure
( UnfurledJoin
{ unfurledJoin =
Join
{ joinSelect =
Select
{ selectProjections =
OSet.fromList
[ AggregateProjection
Aliased
{ aliasedThing = aggregate,
aliasedAlias = alias
}
],
selectSqlTop = NoTop,
selectGroupBy = [],
selectFrom = selectFrom,
selectJoins = [],
selectWhere =
Where
(foreignKeyConditions <> [whereExpression]),
selectOrderBy = Nothing,
selectSqlOffset = Nothing,
selectFinalWantedFields = Nothing
},
joinFieldName = "",
joinRightTable = EntityAlias "",
joinType = OnlessJoin,
joinTop = NoTop,
joinOffset = Nothing
},
unfurledObjectTableAlias = Nothing
}
)
)
pure
( FieldName {fNameEntity = joinAliasEntity, fName = alias},
Nothing
)
-- | Produce a valid ORDER BY construct, telling about any joins
-- needed on the side.
fromAnnOrderByItemG ::
IR.AnnotatedOrderByItemG 'MySQL 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 Asc obiType
pure OrderBy {..}
fromSelectArgsG :: IR.SelectArgsG 'MySQL Expression -> ReaderT EntityAlias FromIr Args
fromSelectArgsG selectArgsG = do
let argsOffset = fromIntegral <$> moffset
argsWhere <-
maybe (pure mempty) (fmap (Where . pure) . fromAnnBoolExp) mannBoolExp
argsTop <-
maybe (pure mempty) (pure . Top) mlimit
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
-- | 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 'MySQL Expression ->
ReaderT EntityAlias FromIr Expression
fromAnnColumnField _stringifyNumbers annColumnField = do
fieldName <- fromColumn column
if typ == IR.ColumnScalar MySQL.Geometry
then pure $ MethodExpression (ColumnExpression fieldName) "STAsText" []
else pure (ColumnExpression fieldName)
where
IR.AnnColumnField
{ _acfColumn = column,
_acfType = typ,
_acfAsText = _asText :: Bool,
_acfOp = _ :: Maybe (IR.ColumnOp 'MySQL)
} = annColumnField
fromRelName :: IR.RelName -> FromIr Text
fromRelName relName =
pure (IR.relNameToTxt relName)
-- fromAggregateField :: IR.AggregateField 'MySQL -> 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 fromColumn names
-- DistinctCountable names -> DistinctCountable <$> traverse fromColumn names
-- IR.AFOp _ -> error "fromAggregatefield: not implemented"
fromTableAggregateFieldG ::
(IR.FieldName, IR.TableAggregateFieldG 'MySQL Void Expression) -> ReaderT EntityAlias FromIr FieldSource
fromTableAggregateFieldG (IR.FieldName _name, _field) = error "fromTableAggregateFieldG: not implemented yet"
fieldSourceProjections :: FieldSource -> [Projection]
fieldSourceProjections =
\case
ExpressionFieldSource aliasedExpression ->
pure (ExpressionProjection aliasedExpression)
JoinFieldSource Aliased {aliasedThing = Join {..}} ->
map
( \(_left, right@(FieldName {fName})) ->
ExpressionProjection
Aliased
{ aliasedAlias = fName,
aliasedThing = ColumnExpression right
}
)
fields
where
fields =
case joinType of
ArrayJoin fs -> fs
ObjectJoin fs -> fs
ArrayAggregateJoin fs -> fs
OnlessJoin -> mempty
AggregateFieldSource aggregates -> fmap AggregateProjection aggregates
fieldSourceJoin :: FieldSource -> Maybe Join
fieldSourceJoin =
\case
JoinFieldSource aliasedJoin -> pure (aliasedThing aliasedJoin)
ExpressionFieldSource {} -> Nothing
AggregateFieldSource {} -> Nothing
fromSelectAggregate ::
Maybe (EntityAlias, HashMap Column Column) ->
IR.AnnSelectG 'MySQL (IR.TableAggregateFieldG 'MySQL Void) Expression ->
FromIr Select
fromSelectAggregate mparentRelationship annSelectG = do
selectFrom <-
case from of
IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject
IR.FromIdentifier {} -> refute $ pure IdentifierNotSupported
IR.FromFunction {} -> refute $ pure FunctionNotSupported
_mforeignKeyConditions <- fmap (Where . fromMaybe []) $
for mparentRelationship $
\(entityAlias, mapping) ->
runReaderT (fromMapping selectFrom mapping) entityAlias
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 = OSet.fromList selectProjections,
selectFrom = selectFrom,
selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources,
selectWhere = argsWhere <> Where [filterExpression],
selectOrderBy = argsOrderBy,
selectSqlOffset = argsOffset,
selectSqlTop = permissionBasedTop <> argsTop,
selectFinalWantedFields = Nothing,
selectGroupBy = []
}
where
permissionBasedTop =
maybe NoTop Top mPermLimit
IR.AnnSelectG
{ _asnFields = fields,
_asnFrom = from,
_asnPerm = perm,
_asnArgs = args,
_asnStrfyNum = _num
} = annSelectG
IR.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm
-- _fromTableAggFieldG ::
-- (Int, (IR.FieldName, IR.TableAggregateFieldG 'MySQL Void Expression)) ->
-- Maybe (ReaderT EntityAlias FromIr (Int, (IR.FieldName, [Projection])))
-- _fromTableAggFieldG = \case
-- (index, (fieldName, IR.TAFAgg (aggregateFields :: [(IR.FieldName, IR.AggregateField 'MySQL)]))) -> Just do
-- aggregates <-
-- for aggregateFields \(fieldName', aggregateField) ->
-- fromAggregateField aggregateField <&> \aliasedThing ->
-- Aliased {aliasedAlias = IR.getFieldNameTxt fieldName', ..}
-- pure (index, (fieldName, fieldSourceProjections $ AggregateFieldSource aggregates))
-- _ -> Nothing
-- _fromTableNodesFieldG ::
-- Map TableName EntityAlias ->
-- StringifyNumbers ->
-- (Int, (IR.FieldName, IR.TableAggregateFieldG 'MySQL Void Expression)) ->
-- Maybe (ReaderT EntityAlias FromIr (Int, (IR.FieldName, [Projection])))
-- _fromTableNodesFieldG argsExistingJoins stringifyNumbers = \case
-- (index, (fieldName, IR.TAFNodes () (annFieldsG :: [(IR.FieldName, IR.AnnFieldG 'MySQL Void Expression)]))) -> Just do
-- fieldSources' <- fromAnnFieldsG argsExistingJoins stringifyNumbers `traverse` annFieldsG
-- let nodesProjections' :: [Projection] = concatMap fieldSourceProjections fieldSources'
-- pure (index, (fieldName, nodesProjections'))
-- _ -> Nothing
-- -- | Get FieldSource from a TAFExp type table aggregate field
-- _fromTableExpFieldG ::
-- (Int, (IR.FieldName, IR.TableAggregateFieldG 'MySQL Void Expression)) ->
-- Maybe (ReaderT EntityAlias FromIr (Int, [Projection]))
-- _fromTableExpFieldG = \case
-- (index, (IR.FieldName name, IR.TAFExp text)) -> Just $
-- pure
-- (index, fieldSourceProjections $
-- ExpressionFieldSource
-- Aliased
-- { aliasedThing = ValueExpression (TextValue text)
-- , aliasedAlias = name
-- })
-- _ -> Nothing
fromArrayAggregateSelectG ::
IR.AnnRelationSelectG 'MySQL (IR.AnnAggregateSelectG 'MySQL 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 (generateEntityAlias (ArrayAggregateTemplate fieldName))
joinOn <- fromMappingFieldNames (EntityAlias alias) mapping
pure
Join
{ joinSelect = joinSelect' {selectSqlTop = NoTop, selectSqlOffset = Nothing},
joinFieldName = "",
joinRightTable = EntityAlias "",
joinType = ArrayAggregateJoin joinOn,
joinTop = selectSqlTop joinSelect',
joinOffset = selectSqlOffset joinSelect'
}
where
IR.AnnRelationSelectG
{ aarRelationshipName,
aarColumnMapping = mapping :: HashMap Column Column,
aarAnnSelect = annSelectG
} = annRelationSelectG
fromArraySelectG :: IR.ArraySelectG 'MySQL Void Expression -> ReaderT EntityAlias FromIr Join
fromArraySelectG =
\case
IR.ASSimple arrayRelationSelectG ->
fromArrayRelationSelectG arrayRelationSelectG
IR.ASAggregate arrayAggregateSelectG ->
fromArrayAggregateSelectG arrayAggregateSelectG
fromObjectRelationSelectG ::
IR.ObjectRelationSelectG 'MySQL Void Expression ->
ReaderT EntityAlias FromIr Join
fromObjectRelationSelectG annRelationSelectG = do
from <- lift $ fromQualifiedTable tableFrom
let entityAlias :: EntityAlias = fromAlias from
fieldSources <-
local
(const entityAlias)
(traverse (fromAnnFieldsG IR.LeaveNumbersAlone) fields)
let selectProjections =
concatMap (toList . fieldSourceProjections) fieldSources
filterExpression <- local (const entityAlias) (fromAnnBoolExp tableFilter)
joinOn <- fromMappingFieldNames entityAlias mapping
let joinFieldProjections =
map
( \(fieldName', _) ->
FieldNameProjection
Aliased
{ aliasedThing = fieldName',
aliasedAlias = fName fieldName'
}
)
joinOn
joinFieldName <- lift (fromRelName aarRelationshipName)
pure
Join
{ joinSelect =
Select
{ selectOrderBy = Nothing,
selectProjections =
OSet.fromList joinFieldProjections
<> OSet.fromList selectProjections, --Ordering is right-biased.
selectGroupBy = [],
selectFrom = from,
selectJoins = mapMaybe fieldSourceJoin fieldSources,
selectWhere = Where [filterExpression],
selectSqlTop = NoTop,
selectSqlOffset = Nothing,
selectFinalWantedFields = pure (fieldTextNames fields)
},
joinFieldName,
joinRightTable = EntityAlias "",
joinType = ObjectJoin joinOn,
joinTop = NoTop,
joinOffset = Nothing
}
where
IR.AnnObjectSelectG
{ _aosFields = fields :: IR.AnnFieldsG 'MySQL Void Expression,
_aosTableFrom = tableFrom :: TableName,
_aosTableFilter = tableFilter :: IR.AnnBoolExp 'MySQL Expression
} = annObjectSelectG
IR.AnnRelationSelectG
{ aarRelationshipName,
aarColumnMapping = mapping :: HashMap Column Column,
aarAnnSelect = annObjectSelectG :: IR.AnnObjectSelectG 'MySQL Void Expression
} = annRelationSelectG
isEmptyExpression :: Expression -> Bool
isEmptyExpression (AndExpression []) = True
isEmptyExpression (OrExpression []) = True
isEmptyExpression _ = False
fromSelectRows :: IR.AnnSelectG 'MySQL (IR.AnnFieldG 'MySQL Void) Expression -> FromIr Select
fromSelectRows annSelectG = do
selectFrom <-
case from of
IR.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject
IR.FromIdentifier {} -> refute $ pure IdentifierNotSupported
IR.FromFunction {} -> refute $ pure FunctionNotSupported
Args
{ argsOrderBy,
argsWhere,
argsJoins,
argsDistinct = Proxy,
argsOffset,
argsTop
} <-
runReaderT (fromSelectArgsG args) (fromAlias selectFrom)
fieldSources <-
runReaderT
(traverse (fromAnnFieldsG stringifyNumbers) fields)
(fromAlias selectFrom)
filterExpression <-
runReaderT (fromAnnBoolExp permFilter) (fromAlias selectFrom)
let selectProjections =
concatMap (toList . fieldSourceProjections) fieldSources
pure
Select
{ selectOrderBy = argsOrderBy,
selectGroupBy = [],
selectProjections = OSet.fromList selectProjections,
selectFrom = selectFrom,
selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources,
selectWhere = argsWhere <> Where ([filterExpression | not (isEmptyExpression filterExpression)]),
selectSqlOffset = argsOffset,
selectSqlTop = permissionBasedTop <> argsTop,
selectFinalWantedFields = pure (fieldTextNames fields)
}
where
permissionBasedTop =
maybe NoTop Top mPermLimit
IR.AnnSelectG
{ _asnFields = fields,
_asnFrom = from,
_asnPerm = perm,
_asnArgs = args,
_asnStrfyNum = stringifyNumbers
} = annSelectG
IR.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm
fromArrayRelationSelectG :: IR.ArrayRelationSelectG 'MySQL Void Expression -> ReaderT EntityAlias FromIr Join
fromArrayRelationSelectG annRelationSelectG = do
joinFieldName <- lift (fromRelName aarRelationshipName)
sel <- lift (fromSelectRows annSelectG)
joinOn <- fromMappingFieldNames (fromAlias (selectFrom sel)) mapping
let joinFieldProjections =
map
( \(fieldName', _) ->
FieldNameProjection
Aliased
{ aliasedThing = fieldName',
aliasedAlias = fName fieldName'
}
)
joinOn
pure
Join
{ joinSelect =
sel
{ selectProjections =
OSet.fromList joinFieldProjections <> selectProjections sel,
-- Above: Ordering is right-biased.
selectSqlTop = NoTop,
selectSqlOffset = Nothing
},
joinRightTable = fromAlias (selectFrom sel),
joinType = ArrayJoin joinOn,
-- Above: Needed by DataLoader to determine the type of
-- Haskell-native join to perform.
joinFieldName,
joinTop = selectSqlTop sel,
joinOffset = selectSqlOffset sel
}
where
IR.AnnRelationSelectG
{ aarRelationshipName,
aarColumnMapping = mapping :: HashMap Column Column,
aarAnnSelect = annSelectG
} = annRelationSelectG
-- | The main sources of fields, either constants, fields or via joins.
fromAnnFieldsG ::
IR.StringifyNumbers ->
(IR.FieldName, IR.AnnFieldG 'MySQL Void Expression) ->
ReaderT EntityAlias FromIr FieldSource
fromAnnFieldsG 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 = ValueExpression (TextValue text),
aliasedAlias = name
}
)
IR.AFObjectRelation objectRelationSelectG ->
fmap
( \aliasedThing ->
JoinFieldSource (Aliased {aliasedThing, aliasedAlias = name})
)
(fromObjectRelationSelectG objectRelationSelectG)
IR.AFArrayRelation arraySelectG ->
fmap
( \aliasedThing ->
JoinFieldSource (Aliased {aliasedThing, aliasedAlias = name})
)
(fromArraySelectG arraySelectG)
mkSQLSelect ::
IR.JsonAggSelect ->
IR.AnnSelectG 'MySQL (IR.AnnFieldG 'MySQL Void) Expression ->
FromIr Select
mkSQLSelect jsonAggSelect annSimpleSel = do
case jsonAggSelect of
IR.JASMultipleRows -> fromSelectRows annSimpleSel
IR.JASSingleObject ->
fromSelectRows annSimpleSel <&> \sel ->
sel
{ selectSqlTop = Top 1
}
-- | Convert from the IR database query into a select.
fromRootField :: IR.QueryDB 'MySQL 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
fromMappingFieldNames ::
EntityAlias ->
HashMap Column Column ->
ReaderT EntityAlias FromIr [(FieldName, FieldName)]
fromMappingFieldNames localFrom =
traverse
( \(remoteColumn, localColumn) -> do
localFieldName <- local (const localFrom) (fromColumn localColumn)
remoteFieldName <- fromColumn remoteColumn
pure
( (,)
(localFieldName)
(remoteFieldName)
)
)
. HM.toList
fieldTextNames :: IR.AnnFieldsG 'MySQL Void Expression -> [Text]
fieldTextNames = fmap (\(IR.FieldName name, _) -> name)