refactor: Split up Types.hs and logically organize modules (#1793)
This commit is contained in:
Remo Rechkemmer
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{-# LANGUAGE DuplicateRecordFields #-}
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{-|
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Module : PostgREST.Query.QueryBuilder
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Description : PostgREST SQL queries generating functions.
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This module provides functions to consume data types that
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represent database queries (e.g. ReadRequest, MutateRequest) and SqlFragment
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to produce SqlQuery type outputs.
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-}
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module PostgREST.Query.QueryBuilder
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( readRequestToQuery
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, mutateRequestToQuery
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, readRequestToCountQuery
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, requestToCallProcQuery
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, limitedQuery
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) where
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import qualified Data.ByteString.Char8 as BS
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import qualified Data.Set as S
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import qualified Hasql.DynamicStatements.Snippet as H
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import Data.Tree (Tree (..))
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import PostgREST.DbStructure.Identifiers (FieldName,
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QualifiedIdentifier (..))
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import PostgREST.DbStructure.Proc (PgArg (..))
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import PostgREST.DbStructure.Relation (Cardinality (..),
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Relation (..))
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import PostgREST.DbStructure.Table (Table (..))
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import PostgREST.Request.ApiRequest (PayloadJSON (..))
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import PostgREST.Request.Preferences (PreferParameters (..),
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PreferResolution (..))
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import PostgREST.Query.SqlFragment
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import PostgREST.Request.Types
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import Protolude
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readRequestToQuery :: ReadRequest -> H.Snippet
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readRequestToQuery (Node (Select colSelects mainQi tblAlias implJoins logicForest joinConditions_ ordts range, _) forest) =
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"SELECT " <>
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intercalateSnippet ", " ((pgFmtSelectItem qi <$> colSelects) ++ selects) <>
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"FROM " <> H.sql (BS.intercalate ", " (tabl : implJs)) <> " " <>
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intercalateSnippet " " joins <> " " <>
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(if null logicForest && null joinConditions_ then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest ++ map pgFmtJoinCondition joinConditions_))
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<> " " <>
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(if null ordts then mempty else "ORDER BY " <> intercalateSnippet ", " (map (pgFmtOrderTerm qi) ordts)) <> " " <>
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limitOffsetF range
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where
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implJs = fromQi <$> implJoins
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tabl = fromQi mainQi <> maybe mempty (\a -> " AS " <> pgFmtIdent a) tblAlias
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qi = maybe mainQi (QualifiedIdentifier mempty) tblAlias
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(joins, selects) = foldr getJoinsSelects ([],[]) forest
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getJoinsSelects :: ReadRequest -> ([H.Snippet], [H.Snippet]) -> ([H.Snippet], [H.Snippet])
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getJoinsSelects rr@(Node (_, (name, Just Relation{relType=relTyp,relTable=Table{tableName=table}}, alias, _, _)) _) (j,s) =
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let subquery = readRequestToQuery rr in
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case relTyp of
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M2O ->
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let aliasOrName = fromMaybe name alias
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localTableName = pgFmtIdent $ table <> "_" <> aliasOrName
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sel = H.sql ("row_to_json(" <> localTableName <> ".*) AS " <> pgFmtIdent aliasOrName)
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joi = " LEFT JOIN LATERAL( " <> subquery <> " ) AS " <> H.sql localTableName <> " ON TRUE " in
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(joi:j,sel:s)
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_ ->
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let sel = "COALESCE (("
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<> "SELECT json_agg(" <> H.sql (pgFmtIdent table) <> ".*) "
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<> "FROM (" <> subquery <> ") " <> H.sql (pgFmtIdent table) <> " "
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<> "), '[]') AS " <> H.sql (pgFmtIdent (fromMaybe name alias)) in
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(j,sel:s)
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getJoinsSelects (Node (_, (_, Nothing, _, _, _)) _) _ = ([], [])
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mutateRequestToQuery :: MutateRequest -> H.Snippet
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mutateRequestToQuery (Insert mainQi iCols body onConflct putConditions returnings) =
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"WITH " <> normalizedBody body <> " " <>
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"INSERT INTO " <> H.sql (fromQi mainQi) <> H.sql (if S.null iCols then " " else "(" <> cols <> ") ") <>
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"SELECT " <> H.sql cols <> " " <>
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H.sql ("FROM json_populate_recordset (null::" <> fromQi mainQi <> ", " <> selectBody <> ") _ ") <>
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-- Only used for PUT
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(if null putConditions then mempty else "WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree (QualifiedIdentifier mempty "_") <$> putConditions)) <>
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H.sql (BS.unwords [
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maybe "" (\(oncDo, oncCols) ->
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if null oncCols then
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mempty
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else
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"ON CONFLICT(" <> BS.intercalate ", " (pgFmtIdent <$> oncCols) <> ") " <> case oncDo of
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IgnoreDuplicates ->
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"DO NOTHING"
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MergeDuplicates ->
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if S.null iCols
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then "DO NOTHING"
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else "DO UPDATE SET " <> BS.intercalate ", " (pgFmtIdent <> const " = EXCLUDED." <> pgFmtIdent <$> S.toList iCols)
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) onConflct,
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returningF mainQi returnings
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])
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where
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cols = BS.intercalate ", " $ pgFmtIdent <$> S.toList iCols
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mutateRequestToQuery (Update mainQi uCols body logicForest returnings) =
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if S.null uCols
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-- if there are no columns we cannot do UPDATE table SET {empty}, it'd be invalid syntax
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-- selecting an empty resultset from mainQi gives us the column names to prevent errors when using &select=
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-- the select has to be based on "returnings" to make computed overloaded functions not throw
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then H.sql ("SELECT " <> emptyBodyReturnedColumns <> " FROM " <> fromQi mainQi <> " WHERE false")
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else
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"WITH " <> normalizedBody body <> " " <>
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"UPDATE " <> H.sql (fromQi mainQi) <> " SET " <> H.sql cols <> " " <>
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"FROM (SELECT * FROM json_populate_recordset (null::" <> H.sql (fromQi mainQi) <> " , " <> H.sql selectBody <> " )) _ " <>
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(if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)) <> " " <>
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H.sql (returningF mainQi returnings)
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where
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cols = BS.intercalate ", " (pgFmtIdent <> const " = _." <> pgFmtIdent <$> S.toList uCols)
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emptyBodyReturnedColumns :: SqlFragment
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emptyBodyReturnedColumns
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| null returnings = "NULL"
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| otherwise = BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName mainQi) <$> returnings)
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mutateRequestToQuery (Delete mainQi logicForest returnings) =
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"DELETE FROM " <> H.sql (fromQi mainQi) <> " " <>
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(if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree mainQi) logicForest)) <> " " <>
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H.sql (returningF mainQi returnings)
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requestToCallProcQuery :: QualifiedIdentifier -> [PgArg] -> Maybe PayloadJSON -> Bool -> Maybe PreferParameters -> [FieldName] -> H.Snippet
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requestToCallProcQuery qi pgArgs pj returnsScalar preferParams returnings =
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argsCTE <> sourceBody
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where
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body = pjRaw <$> pj
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paramsAsSingleObject = preferParams == Just SingleObject
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paramsAsMultipleObjects = preferParams == Just MultipleObjects
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(argsCTE, args)
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| null pgArgs = (mempty, mempty)
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| paramsAsSingleObject = ("WITH pgrst_args AS (SELECT NULL)", jsonPlaceHolder body)
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| otherwise = (
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"WITH " <> normalizedBody body <> ", " <>
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H.sql (
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BS.unwords [
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"pgrst_args AS (",
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"SELECT * FROM json_to_recordset(" <> selectBody <> ") AS _(" <> fmtArgs (const mempty) (\a -> " " <> encodeUtf8 (pgaType a)) <> ")",
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")"])
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, H.sql $ if paramsAsMultipleObjects
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then fmtArgs varadicPrefix (\a -> " := pgrst_args." <> pgFmtIdent (pgaName a))
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else fmtArgs varadicPrefix (\a -> " := (SELECT " <> pgFmtIdent (pgaName a) <> " FROM pgrst_args LIMIT 1)")
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)
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fmtArgs :: (PgArg -> SqlFragment) -> (PgArg -> SqlFragment) -> SqlFragment
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fmtArgs argFragPre argFragSuf = BS.intercalate ", " ((\a -> argFragPre a <> pgFmtIdent (pgaName a) <> argFragSuf a) <$> pgArgs)
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varadicPrefix :: PgArg -> SqlFragment
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varadicPrefix a = if pgaVar a then "VARIADIC " else mempty
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sourceBody :: H.Snippet
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sourceBody
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| paramsAsMultipleObjects =
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if returnsScalar
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then "SELECT " <> callIt <> " AS pgrst_scalar FROM pgrst_args"
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else "SELECT pgrst_lat_args.* FROM pgrst_args, " <>
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"LATERAL ( SELECT " <> returnedColumns <> " FROM " <> callIt <> " ) pgrst_lat_args"
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| otherwise =
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if returnsScalar
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then "SELECT " <> callIt <> " AS pgrst_scalar"
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else "SELECT " <> returnedColumns <> " FROM " <> callIt
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callIt :: H.Snippet
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callIt = H.sql (fromQi qi) <> "(" <> args <> ")"
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returnedColumns :: H.Snippet
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returnedColumns
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| null returnings = "*"
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| otherwise = H.sql $ BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName qi) <$> returnings)
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-- | SQL query meant for COUNTing the root node of the Tree.
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-- It only takes WHERE into account and doesn't include LIMIT/OFFSET because it would reduce the COUNT.
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-- SELECT 1 is done instead of SELECT * to prevent doing expensive operations(like functions based on the columns)
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-- inside the FROM target.
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readRequestToCountQuery :: ReadRequest -> H.Snippet
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readRequestToCountQuery (Node (Select{from=qi, where_=logicForest}, _) _) =
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"SELECT 1 " <> "FROM " <> H.sql (fromQi qi) <> " " <>
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if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest)
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limitedQuery :: H.Snippet -> Maybe Integer -> H.Snippet
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limitedQuery query maxRows = query <> H.sql (maybe mempty (\x -> " LIMIT " <> BS.pack (show x)) maxRows)
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