{-# LANGUAGE FlexibleInstances #-} {-# OPTIONS_GHC -fno-warn-orphans #-} {-| Module : PostgREST.QueryBuilder Description : PostgREST SQL generating functions. This module provides functions to consume data types that represent database objects (e.g. Relation, Schema, SqlQuery) and produces SQL Statements. Any function that outputs a SQL fragment should be in this module. -} module PostgREST.QueryBuilder ( callProc , createReadStatement , createWriteStatement , pgFmtIdent , pgFmtLit , requestToQuery , requestToCountQuery , unquoted , ResultsWithCount , pgFmtEnvVar ) where import qualified Hasql.Query as H import qualified Hasql.Encoders as HE import qualified Hasql.Decoders as HD import qualified Data.Aeson as JSON import PostgREST.Config (pgVersion96) import PostgREST.RangeQuery (NonnegRange, rangeLimit, rangeOffset, allRange) import Data.Functor.Contravariant (contramap) import qualified Data.HashMap.Strict as HM import Data.Maybe import Data.Text (intercalate, unwords, replace, isInfixOf, toLower) import qualified Data.Text as T (map, takeWhile, null) import qualified Data.Text.Encoding as T import Data.Tree (Tree(..)) import qualified Data.Vector as V import PostgREST.Types import Text.InterpolatedString.Perl6 (qc) import qualified Data.ByteString.Char8 as BS import Data.Scientific ( FPFormat (..) , formatScientific , isInteger ) import Protolude hiding (from, intercalate, ord, cast, replace) import PostgREST.ApiRequest (PreferRepresentation (..)) {-| The generic query result format used by API responses. The location header is represented as a list of strings containing variable bindings like @"k1=eq.42"@, or the empty list if there is no location header. -} type ResultsWithCount = (Maybe Int64, Int64, [BS.ByteString], BS.ByteString) standardRow :: HD.Row ResultsWithCount standardRow = (,,,) <$> HD.nullableValue HD.int8 <*> HD.value HD.int8 <*> HD.value header <*> HD.value HD.bytea where header = HD.array $ HD.arrayDimension replicateM $ HD.arrayValue HD.bytea noLocationF :: Text noLocationF = "array[]::text[]" {-| Read and Write api requests use a similar response format which includes various record counts and possible location header. This is the decoder for that common type of query. -} decodeStandard :: HD.Result ResultsWithCount decodeStandard = HD.singleRow standardRow decodeStandardMay :: HD.Result (Maybe ResultsWithCount) decodeStandardMay = HD.maybeRow standardRow {-| JSON and CSV payloads from the client are given to us as PayloadJSON (objects who all have the same keys), and we turn this into an old fasioned JSON array -} encodeUniformObjs :: HE.Params PayloadJSON encodeUniformObjs = contramap (JSON.Array . V.map JSON.Object . unPayloadJSON) (HE.value HE.json) createReadStatement :: SqlQuery -> SqlQuery -> Bool -> Bool -> Bool -> Maybe FieldName -> H.Query () ResultsWithCount createReadStatement selectQuery countQuery isSingle countTotal asCsv binaryField = unicodeStatement sql HE.unit decodeStandard False where sql = [qc| WITH {sourceCTEName} AS ({selectQuery}) SELECT {cols} FROM ( SELECT * FROM {sourceCTEName}) _postgrest_t |] countResultF = if countTotal then "("<>countQuery<>")" else "null" cols = intercalate ", " [ countResultF <> " AS total_result_set", "pg_catalog.count(_postgrest_t) AS page_total", noLocationF <> " AS header", bodyF <> " AS body" ] bodyF | asCsv = asCsvF | isSingle = asJsonSingleF | isJust binaryField = asBinaryF $ fromJust binaryField | otherwise = asJsonF createWriteStatement :: SqlQuery -> SqlQuery -> Bool -> Bool -> Bool -> PreferRepresentation -> [Text] -> H.Query PayloadJSON (Maybe ResultsWithCount) createWriteStatement selectQuery mutateQuery wantSingle wantHdrs asCsv rep pKeys = unicodeStatement sql encodeUniformObjs decodeStandardMay True where sql = case rep of None -> [qc| WITH {sourceCTEName} AS ({mutateQuery}) SELECT '', 0, {noLocationF}, '' |] HeadersOnly -> [qc| WITH {sourceCTEName} AS ({mutateQuery}) SELECT {cols} FROM (SELECT 1 FROM {sourceCTEName}) _postgrest_t |] Full -> [qc| WITH {sourceCTEName} AS ({mutateQuery}) SELECT {cols} FROM ({selectQuery}) _postgrest_t |] cols = intercalate ", " [ "'' AS total_result_set", -- when updateing it does not make sense "pg_catalog.count(_postgrest_t) AS page_total", if wantHdrs then locationF pKeys else noLocationF <> " AS header", if rep == Full then bodyF <> " AS body" else "''" ] bodyF | asCsv = asCsvF | wantSingle = asJsonSingleF | otherwise = asJsonF type ProcResults = (Maybe Int64, Int64, ByteString, ByteString) callProc :: QualifiedIdentifier -> JSON.Object -> Bool -> SqlQuery -> SqlQuery -> Bool -> Bool -> Bool -> Bool -> Bool -> Bool -> Maybe FieldName -> PgVersion -> H.Query () (Maybe ProcResults) callProc qi params returnsScalar selectQuery countQuery countTotal isSingle paramsAsJson asCsv asBinary isReadOnly binaryField pgVer = unicodeStatement sql HE.unit decodeProc True where sql = if returnsScalar then [qc| WITH {sourceCTEName} AS (select {fromQi qi}({_args})) SELECT {countResultF} AS total_result_set, 1 AS page_total, {scalarBodyF} AS body, {responseHeaders} AS response_headers FROM ({selectQuery}) _postgrest_t;|] else [qc| WITH {sourceCTEName} AS (select * from {fromQi qi}({_args})) SELECT {countResultF} AS total_result_set, pg_catalog.count(_postgrest_t) AS page_total, {bodyF} AS body, {responseHeaders} AS response_headers FROM ({selectQuery}) _postgrest_t;|] countResultF = if countTotal then "( "<> countQuery <> ")" else "null::bigint" :: Text _args = if paramsAsJson && not isReadOnly then insertableValueWithType "json" $ JSON.Object params else intercalate "," $ map _assignment (HM.toList params) _procName = qiName qi _assignment (n,v) = pgFmtIdent n <> ":=" <> insertableValue v responseHeaders = if pgVer >= pgVersion96 then "coalesce(nullif(current_setting('response.headers', true), ''), '[]')" :: Text -- nullif is used because of https://gist.github.com/steve-chavez/8d7033ea5655096903f3b52f8ed09a15 else "'[]'" :: Text decodeProc = HD.maybeRow procRow procRow = (,,,) <$> HD.nullableValue HD.int8 <*> HD.value HD.int8 <*> HD.value HD.bytea <*> HD.value HD.bytea scalarBodyF | asBinary = asBinaryF _procName | otherwise = "(row_to_json(_postgrest_t)->" <> pgFmtLit _procName <> ")::character varying" bodyF | isSingle = asJsonSingleF | asCsv = asCsvF | isJust binaryField = asBinaryF $ fromJust binaryField | otherwise = asJsonF pgFmtIdent :: SqlFragment -> SqlFragment pgFmtIdent x = "\"" <> replace "\"" "\"\"" (trimNullChars $ toS x) <> "\"" pgFmtLit :: SqlFragment -> SqlFragment pgFmtLit x = let trimmed = trimNullChars x escaped = "'" <> replace "'" "''" trimmed <> "'" slashed = replace "\\" "\\\\" escaped in if "\\" `isInfixOf` escaped then "E" <> slashed else slashed requestToCountQuery :: Schema -> DbRequest -> SqlQuery requestToCountQuery _ (DbMutate _) = undefined requestToCountQuery schema (DbRead (Node (Select _ _ logicForest _ _, (mainTbl, _, _, _)) _)) = unwords [ "SELECT pg_catalog.count(*)", "FROM ", fromQi qi, ("WHERE " <> intercalate " AND " (map (pgFmtLogicTree qi) filteredLogic)) `emptyOnFalse` null filteredLogic ] where qi = removeSourceCTESchema schema mainTbl -- all foreing key filters are root nodes(see addFilterToLogicForest), only those are filtered nonFKRoot :: LogicTree -> Bool nonFKRoot (Stmnt (Filter _ (OpExpr _ (Join _ _)))) = False nonFKRoot (Stmnt _) = True nonFKRoot Expr{} = True filteredLogic = filter nonFKRoot logicForest requestToQuery :: Schema -> Bool -> DbRequest -> SqlQuery requestToQuery schema isParent (DbRead (Node (Select colSelects tbls logicForest ord range, (nodeName, maybeRelation, _, _)) forest)) = query where mainTbl = fromMaybe nodeName (tableName . relTable <$> maybeRelation) qi = removeSourceCTESchema schema mainTbl toQi = removeSourceCTESchema schema query = unwords [ "SELECT ", intercalate ", " (map (pgFmtSelectItem qi) colSelects ++ selects), "FROM ", intercalate ", " (map (fromQi . toQi) tbls), unwords joins, ("WHERE " <> intercalate " AND " (map (pgFmtLogicTree qi) logicForest)) `emptyOnFalse` null logicForest, orderF (fromMaybe [] ord), if isParent then "" else limitF range ] orderF ts = if null ts then "" else "ORDER BY " <> clause where clause = intercalate "," (map queryTerm ts) queryTerm :: OrderTerm -> Text queryTerm t = " " <> toS (pgFmtField qi $ otTerm t) <> " " <> maybe "" show (otDirection t) <> " " <> maybe "" show (otNullOrder t) <> " " (joins, selects) = foldr getQueryParts ([],[]) forest getQueryParts :: Tree ReadNode -> ([SqlFragment], [SqlFragment]) -> ([SqlFragment], [SqlFragment]) getQueryParts (Node n@(_, (name, Just Relation{relType=Child,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (j,sel:s) where sel = "COALESCE((" <> "SELECT json_agg(" <> pgFmtIdent table <> ".*) " <> "FROM (" <> subquery <> ") " <> pgFmtIdent table <> "), '[]') AS " <> pgFmtIdent (fromMaybe name alias) where subquery = requestToQuery schema False (DbRead (Node n forst)) getQueryParts (Node n@(_, (name, Just Relation{relType=Parent,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (joi:j,sel:s) where aliasOrName = fromMaybe name alias localTableName = pgFmtIdent $ table <> "_" <> aliasOrName sel = "row_to_json(" <> localTableName <> ".*) AS " <> pgFmtIdent aliasOrName joi = " LEFT JOIN LATERAL( " <> subquery <> " ) AS " <> localTableName <> " ON TRUE " where subquery = requestToQuery schema True (DbRead (Node n forst)) getQueryParts (Node n@(_, (name, Just Relation{relType=Many,relTable=Table{tableName=table}}, alias, _)) forst) (j,s) = (j,sel:s) where sel = "COALESCE ((" <> "SELECT json_agg(" <> pgFmtIdent table <> ".*) " <> "FROM (" <> subquery <> ") " <> pgFmtIdent table <> "), '[]') AS " <> pgFmtIdent (fromMaybe name alias) where subquery = requestToQuery schema False (DbRead (Node n forst)) --the following is just to remove the warning --getQueryParts is not total but requestToQuery is called only after addJoinConditions which ensures the only --posible relations are Child Parent Many getQueryParts _ _ = undefined requestToQuery schema _ (DbMutate (Insert mainTbl (PayloadJSON rows) returnings)) = insInto <> vals <> ret where qi = QualifiedIdentifier schema mainTbl cols = map pgFmtIdent $ fromMaybe [] (HM.keys <$> (rows V.!? 0)) colsString = intercalate ", " cols insInto = unwords [ "INSERT INTO" , fromQi qi, if T.null colsString then "" else "(" <> colsString <> ")" ] vals = unwords $ if T.null colsString then if V.null rows then ["SELECT null WHERE false"] else ["DEFAULT VALUES"] else ["SELECT", colsString, "FROM json_populate_recordset(null::" , fromQi qi, ", $1)"] ret = if null returnings then "" else unwords [" RETURNING ", intercalate ", " (map (pgFmtColumn qi) returnings)] requestToQuery schema _ (DbMutate (Update mainTbl (PayloadJSON rows) logicForest returnings)) = case rows V.!? 0 of Just obj -> let assignments = map (\(k,v) -> pgFmtIdent k <> "=" <> insertableValue v) $ HM.toList obj in unwords [ "UPDATE ", fromQi qi, " SET " <> intercalate "," assignments <> " ", ("WHERE " <> intercalate " AND " (map (pgFmtLogicTree qi) logicForest)) `emptyOnFalse` null logicForest, ("RETURNING " <> intercalate ", " (map (pgFmtColumn qi) returnings)) `emptyOnFalse` null returnings ] Nothing -> undefined where qi = QualifiedIdentifier schema mainTbl requestToQuery schema _ (DbMutate (Delete mainTbl logicForest returnings)) = query where qi = QualifiedIdentifier schema mainTbl query = unwords [ "DELETE FROM ", fromQi qi, ("WHERE " <> intercalate " AND " (map (pgFmtLogicTree qi) logicForest)) `emptyOnFalse` null logicForest, ("RETURNING " <> intercalate ", " (map (pgFmtColumn qi) returnings)) `emptyOnFalse` null returnings ] removeSourceCTESchema :: Schema -> TableName -> QualifiedIdentifier removeSourceCTESchema schema tbl = QualifiedIdentifier (if tbl == sourceCTEName then "" else schema) tbl unquoted :: JSON.Value -> Text unquoted (JSON.String t) = t unquoted (JSON.Number n) = toS $ formatScientific Fixed (if isInteger n then Just 0 else Nothing) n unquoted (JSON.Bool b) = show b unquoted v = toS $ JSON.encode v -- private functions asCsvF :: SqlFragment asCsvF = asCsvHeaderF <> " || '\n' || " <> asCsvBodyF where asCsvHeaderF = "(SELECT coalesce(string_agg(a.k, ','), '')" <> " FROM (" <> " SELECT json_object_keys(r)::TEXT as k" <> " FROM ( " <> " SELECT row_to_json(hh) as r from " <> sourceCTEName <> " as hh limit 1" <> " ) s" <> " ) a" <> ")" asCsvBodyF = "coalesce(string_agg(substring(_postgrest_t::text, 2, length(_postgrest_t::text) - 2), '\n'), '')" asJsonF :: SqlFragment asJsonF = "coalesce(json_agg(_postgrest_t), '[]')::character varying" asJsonSingleF :: SqlFragment --TODO! unsafe when the query actually returns multiple rows, used only on inserting and returning single element asJsonSingleF = "coalesce(string_agg(row_to_json(_postgrest_t)::text, ','), '')::character varying " asBinaryF :: FieldName -> SqlFragment asBinaryF fieldName = "coalesce(string_agg(_postgrest_t." <> pgFmtIdent fieldName <> ", ''), '')" locationF :: [Text] -> SqlFragment locationF pKeys = "(" <> " WITH s AS (SELECT row_to_json(ss) as r from " <> sourceCTEName <> " as ss limit 1)" <> " SELECT array_agg(json_data.key || '=' || coalesce('eq.' || json_data.value, 'is.null'))" <> " FROM s, json_each_text(s.r) AS json_data" <> ( if null pKeys then "" else " WHERE json_data.key IN ('" <> intercalate "','" pKeys <> "')" ) <> ")" limitF :: NonnegRange -> SqlFragment limitF r = if r == allRange then "" else "LIMIT " <> limit <> " OFFSET " <> offset where limit = maybe "ALL" show $ rangeLimit r offset = show $ rangeOffset r fromQi :: QualifiedIdentifier -> SqlFragment fromQi t = (if s == "" then "" else pgFmtIdent s <> ".") <> pgFmtIdent n where n = qiName t s = qiSchema t unicodeStatement :: Text -> HE.Params a -> HD.Result b -> Bool -> H.Query a b unicodeStatement = H.statement . T.encodeUtf8 emptyOnFalse :: Text -> Bool -> Text emptyOnFalse val cond = if cond then "" else val insertableValue :: JSON.Value -> SqlFragment insertableValue JSON.Null = "null" insertableValue v = (<> "::unknown") . pgFmtLit $ unquoted v insertableValueWithType :: Text -> JSON.Value -> SqlFragment insertableValueWithType t v = pgFmtLit (unquoted v) <> "::" <> t pgFmtColumn :: QualifiedIdentifier -> Text -> SqlFragment pgFmtColumn table "*" = fromQi table <> ".*" pgFmtColumn table c = fromQi table <> "." <> pgFmtIdent c pgFmtField :: QualifiedIdentifier -> Field -> SqlFragment pgFmtField table (c, jp) = pgFmtColumn table c <> pgFmtJsonPath jp pgFmtSelectItem :: QualifiedIdentifier -> SelectItem -> SqlFragment pgFmtSelectItem table (f@(_, jp), Nothing, alias, _) = pgFmtField table f <> pgFmtAs jp alias pgFmtSelectItem table (f@(_, jp), Just cast, alias, _) = "CAST (" <> pgFmtField table f <> " AS " <> cast <> " )" <> pgFmtAs jp alias pgFmtFilter :: QualifiedIdentifier -> Filter -> SqlFragment pgFmtFilter table (Filter fld (OpExpr hasNot oper)) = notOp <> " " <> case oper of Op op val -> pgFmtFieldOp op <> " " <> case op of "like" -> unknownLiteral (T.map star val) "ilike" -> unknownLiteral (T.map star val) "is" -> whiteList val _ -> unknownLiteral val In vals -> pgFmtField table fld <> " " <> let emptyValForIn = "= any('{}') " in -- Workaround because for postgresql "col IN ()" is invalid syntax, we instead do "col = any('{}')" case ((&&) (length vals == 1) . T.null) <$> headMay vals of Just False -> sqlOperator "in" <> "(" <> intercalate ", " (map unknownLiteral vals) <> ") " Just True -> emptyValForIn Nothing -> emptyValForIn Fts op lang val -> pgFmtFieldOp op <> "(" <> maybe "" ((<> ", ") . pgFmtLit) lang <> unknownLiteral val <> ") " Join fQi (ForeignKey Column{colTable=Table{tableName=fTableName}, colName=fColName}) -> pgFmtField fQi fld <> " = " <> pgFmtColumn (removeSourceCTESchema (qiSchema fQi) fTableName) fColName where pgFmtFieldOp op = pgFmtField table fld <> " " <> sqlOperator op sqlOperator o = HM.lookupDefault "=" o operators notOp = if hasNot then "NOT" else "" star c = if c == '*' then '%' else c unknownLiteral = (<> "::unknown ") . pgFmtLit whiteList :: Text -> SqlFragment whiteList v = fromMaybe (toS (pgFmtLit v) <> "::unknown ") (find ((==) . toLower $ v) ["null","true","false"]) pgFmtLogicTree :: QualifiedIdentifier -> LogicTree -> SqlFragment pgFmtLogicTree qi (Expr hasNot op forest) = notOp <> " (" <> intercalate (" " <> show op <> " ") (pgFmtLogicTree qi <$> forest) <> ")" where notOp = if hasNot then "NOT" else "" pgFmtLogicTree qi (Stmnt flt) = pgFmtFilter qi flt pgFmtJsonPath :: Maybe JsonPath -> SqlFragment pgFmtJsonPath (Just [x]) = "->>" <> pgFmtLit x pgFmtJsonPath (Just (x:xs)) = "->" <> pgFmtLit x <> pgFmtJsonPath ( Just xs ) pgFmtJsonPath _ = "" pgFmtAs :: Maybe JsonPath -> Maybe Alias -> SqlFragment pgFmtAs Nothing Nothing = "" pgFmtAs (Just xx) Nothing = case lastMay xx of Just alias -> " AS " <> pgFmtIdent alias Nothing -> "" pgFmtAs _ (Just alias) = " AS " <> pgFmtIdent alias pgFmtEnvVar :: Text -> (Text, Text) -> SqlFragment pgFmtEnvVar prefix (k, v) = "set local " <> pgFmtIdent (prefix <> k) <> " = " <> pgFmtLit v <> ";" trimNullChars :: Text -> Text trimNullChars = T.takeWhile (/= '\x0')