Add aggregate functions (#2925)
The aggregate functions SUM(), MAX(), MIN(), AVG(), and COUNT() are now supported.
This commit is contained in:
Tim Abdulla
@@ -9,6 +9,7 @@ module PostgREST.Query.SqlFragment
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( noLocationF
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, handlerF
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, countF
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, groupF
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, fromQi
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, limitOffsetF
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, locationF
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@@ -21,6 +22,7 @@ module PostgREST.Query.SqlFragment
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, pgFmtLogicTree
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, pgFmtOrderTerm
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, pgFmtSelectItem
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, pgFmtSpreadSelectItem
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, fromJsonBodyF
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, responseHeadersF
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, responseStatusF
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@@ -54,7 +56,8 @@ import Control.Arrow ((***))
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import Data.Foldable (foldr1)
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import Text.InterpolatedString.Perl6 (qc)
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import PostgREST.ApiRequest.Types (Alias, Cast,
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import PostgREST.ApiRequest.Types (AggregateFunction (..),
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Alias, Cast,
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FtsOperator (..),
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JsonOperand (..),
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JsonOperation (..),
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@@ -75,6 +78,9 @@ import PostgREST.Plan.Types (CoercibleField (..),
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CoercibleFilter (..),
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CoercibleLogicTree (..),
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CoercibleOrderTerm (..),
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CoercibleSelectField (..),
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RelSelectField (..),
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SpreadSelectField (..),
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unknownField)
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import PostgREST.RangeQuery (NonnegRange, allRange,
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rangeLimit, rangeOffset)
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@@ -86,7 +92,7 @@ import PostgREST.SchemaCache.Routine (MediaHandler (..),
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funcReturnsSetOfScalar,
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funcReturnsSingleComposite)
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import Protolude hiding (cast)
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import Protolude hiding (Sum, cast)
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sourceCTEName :: Text
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sourceCTEName = "pgrst_source"
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@@ -258,12 +264,34 @@ pgFmtCoerceNamed :: CoercibleField -> SQL.Snippet
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pgFmtCoerceNamed CoercibleField{cfName=fn, cfTransform=(Just formatterProc)} = pgFmtCallUnary formatterProc (pgFmtIdent fn) <> " AS " <> pgFmtIdent fn
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pgFmtCoerceNamed CoercibleField{cfName=fn} = pgFmtIdent fn
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pgFmtSelectItem :: QualifiedIdentifier -> (CoercibleField, Maybe Cast, Maybe Alias) -> SQL.Snippet
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pgFmtSelectItem table (fld, Nothing, alias) = pgFmtTableCoerce table fld <> pgFmtAs (cfName fld) (cfJsonPath fld) alias
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pgFmtSelectItem :: QualifiedIdentifier -> CoercibleSelectField -> SQL.Snippet
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pgFmtSelectItem table CoercibleSelectField{csField=fld, csAggFunction=agg, csAggCast=aggCast, csCast=cast, csAlias=alias} =
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pgFmtApplyAggregate agg aggCast (pgFmtApplyCast cast (pgFmtTableCoerce table fld)) <> pgFmtAs alias
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pgFmtSpreadSelectItem :: Alias -> SpreadSelectField -> SQL.Snippet
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pgFmtSpreadSelectItem aggAlias SpreadSelectField{ssSelName, ssSelAggFunction, ssSelAggCast, ssSelAlias} =
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pgFmtApplyAggregate ssSelAggFunction ssSelAggCast fullSelName <> pgFmtAs ssSelAlias
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where
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fullSelName = case ssSelName of
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"*" -> pgFmtIdent aggAlias <> ".*"
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_ -> pgFmtIdent aggAlias <> "." <> pgFmtIdent ssSelName
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pgFmtApplyAggregate :: Maybe AggregateFunction -> Maybe Cast -> SQL.Snippet -> SQL.Snippet
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pgFmtApplyAggregate Nothing _ snippet = snippet
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pgFmtApplyAggregate (Just agg) aggCast snippet =
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pgFmtApplyCast aggCast aggregatedSnippet
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where
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convertAggFunction :: AggregateFunction -> SQL.Snippet
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-- Convert from e.g. Sum (the data type) to SUM
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convertAggFunction = SQL.sql . BS.map toUpper . BS.pack . show
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aggregatedSnippet = convertAggFunction agg <> "(" <> snippet <> ")"
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pgFmtApplyCast :: Maybe Cast -> SQL.Snippet -> SQL.Snippet
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pgFmtApplyCast Nothing snippet = snippet
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-- Ideally we'd quote the cast with "pgFmtIdent cast". However, that would invalidate common casts such as "int", "bigint", etc.
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-- Try doing: `select 1::"bigint"` - it'll err, using "int8" will work though. There's some parser magic that pg does that's invalidated when quoting.
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-- Not quoting should be fine, we validate the input on Parsers.
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pgFmtSelectItem table (fld, Just cast, alias) = "CAST (" <> pgFmtTableCoerce table fld <> " AS " <> SQL.sql (encodeUtf8 cast) <> " )" <> pgFmtAs (cfName fld) (cfJsonPath fld) alias
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pgFmtApplyCast (Just cast) snippet = "CAST( " <> snippet <> " AS " <> SQL.sql (encodeUtf8 cast) <> " )"
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-- TODO: At this stage there shouldn't be a Maybe since ApiRequest should ensure that an INSERT/UPDATE has a body
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fromJsonBodyF :: Maybe LBS.ByteString -> [CoercibleField] -> Bool -> Bool -> Bool -> SQL.Snippet
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@@ -395,17 +423,40 @@ pgFmtJsonPath = \case
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pgFmtJsonOperand (JKey k) = unknownLiteral k
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pgFmtJsonOperand (JIdx i) = unknownLiteral i <> "::int"
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pgFmtAs :: FieldName -> JsonPath -> Maybe Alias -> SQL.Snippet
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pgFmtAs _ [] Nothing = mempty
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pgFmtAs fName jp Nothing = case jOp <$> lastMay jp of
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Just (JKey key) -> " AS " <> pgFmtIdent key
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Just (JIdx _) -> " AS " <> pgFmtIdent (fromMaybe fName lastKey)
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-- We get the lastKey because on:
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-- `select=data->1->mycol->>2`, we need to show the result as [ {"mycol": ..}, {"mycol": ..} ]
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-- `select=data->3`, we need to show the result as [ {"data": ..}, {"data": ..} ]
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where lastKey = jVal <$> find (\case JKey{} -> True; _ -> False) (jOp <$> reverse jp)
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Nothing -> mempty
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pgFmtAs _ _ (Just alias) = " AS " <> pgFmtIdent alias
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pgFmtAs :: Maybe Alias -> SQL.Snippet
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pgFmtAs Nothing = mempty
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pgFmtAs (Just alias) = " AS " <> pgFmtIdent alias
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groupF :: QualifiedIdentifier -> [CoercibleSelectField] -> [RelSelectField] -> SQL.Snippet
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groupF qi select relSelect
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| (noSelectsAreAggregated && noRelSelectsAreAggregated) || null groupTerms = mempty
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| otherwise = " GROUP BY " <> intercalateSnippet ", " groupTerms
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where
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noSelectsAreAggregated = null $ [s | s@(CoercibleSelectField { csAggFunction = Just _ }) <- select]
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noRelSelectsAreAggregated = all (\case Spread sels _ -> all (isNothing . ssSelAggFunction) sels; _ -> True) relSelect
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groupTermsFromSelect = mapMaybe (pgFmtGroup qi) select
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groupTermsFromRelSelect = mapMaybe groupTermFromRelSelectField relSelect
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groupTerms = groupTermsFromSelect ++ groupTermsFromRelSelect
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groupTermFromRelSelectField :: RelSelectField -> Maybe SQL.Snippet
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groupTermFromRelSelectField (JsonEmbed { rsSelName }) =
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Just $ pgFmtIdent rsSelName
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groupTermFromRelSelectField (Spread { rsSpreadSel, rsAggAlias }) =
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if null groupTerms
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then Nothing
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else
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Just $ intercalateSnippet ", " groupTerms
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where
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processField :: SpreadSelectField -> Maybe SQL.Snippet
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processField SpreadSelectField{ssSelAggFunction = Just _} = Nothing
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processField SpreadSelectField{ssSelName, ssSelAlias} =
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Just $ pgFmtIdent rsAggAlias <> "." <> pgFmtIdent (fromMaybe ssSelName ssSelAlias)
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groupTerms = mapMaybe processField rsSpreadSel
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pgFmtGroup :: QualifiedIdentifier -> CoercibleSelectField -> Maybe SQL.Snippet
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pgFmtGroup _ CoercibleSelectField{csAggFunction=Just _} = Nothing
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pgFmtGroup _ CoercibleSelectField{csAlias=Just alias, csAggFunction=Nothing} = Just $ pgFmtIdent alias
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pgFmtGroup qi CoercibleSelectField{csField=fld, csAlias=Nothing, csAggFunction=Nothing} = Just $ pgFmtField qi fld
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countF :: SQL.Snippet -> Bool -> (SQL.Snippet, SQL.Snippet)
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countF countQuery shouldCount =
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