refactor: remove SqlFragment and use SQL.Snippet

src/PostgREST/Plan.hs

@@ -271,7 +271,7 @@ addRels schema action allRels parentNode (Node rPlan@ReadPlan{relName,relHint,re
       Node <$> newReadPlan <*> (updateForest . hush $ Node <$> newReadPlan <*> pure forest)
     Nothing -> -- root case
       let
-        newFrom  = QualifiedIdentifier mempty $ decodeUtf8 sourceCTEName
+        newFrom  = QualifiedIdentifier mempty sourceCTEName
         newAlias = Just (qiName $ from rPlan)
         newReadPlan = case action of
           -- the CTE for mutations/rpc is used as WITH sourceCTEName .. SELECT .. FROM sourceCTEName as alias,

src/PostgREST/Query.hs

@@ -24,8 +24,6 @@ import qualified Data.Text.Encoding                as T
 import qualified Hasql.Decoders                    as HD
 import qualified Hasql.DynamicStatements.Snippet   as SQL (Snippet)
 import qualified Hasql.DynamicStatements.Statement as SQL
-import qualified Hasql.Encoders                    as HE
-import qualified Hasql.Statement                   as SQL
 import qualified Hasql.Transaction                 as SQL
 
 import qualified PostgREST.Error              as Error
@@ -51,8 +49,8 @@ import PostgREST.Plan                    (CallReadPlan (..),
                                           MutateReadPlan (..),
                                           WrappedReadPlan (..))
 import PostgREST.Plan.MutatePlan         (MutatePlan (..))
-import PostgREST.Query.SqlFragment       (fromQi, intercalateSnippet,
+import PostgREST.Query.SqlFragment       (escapeIdentList, fromQi,
-                                          pgFmtIdentList,
+                                          intercalateSnippet,
                                           setConfigLocal,
                                           setConfigLocalJson)
 import PostgREST.Query.Statements        (ResultSet (..))
@@ -254,7 +252,7 @@ setPgLocals AppConfig{..} claims role roleSettings req actualPgVersion = lift $
     roleSettingsSql = setConfigLocal mempty <$> roleSettings
     appSettingsSql = setConfigLocal mempty <$> (join bimap toUtf8 <$> configAppSettings)
     searchPathSql =
-      let schemas = pgFmtIdentList (iSchema req : configDbExtraSearchPath) in
+      let schemas = escapeIdentList (iSchema req : configDbExtraSearchPath) in
       setConfigLocal mempty ("search_path", schemas)
     usesLegacyGucs = configDbUseLegacyGucs && actualPgVersion < pgVersion140
 
@@ -269,8 +267,7 @@ setPgLocals AppConfig{..} claims role roleSettings req actualPgVersion = lift $
 runPreReq :: AppConfig -> DbHandler ()
 runPreReq conf = lift $ traverse_ (SQL.statement mempty . stmt) (configDbPreRequest conf)
   where
-    stmt req = SQL.Statement
+    stmt req = SQL.dynamicallyParameterized
       ("select " <> fromQi req <> "()")
-      HE.noParams
       HD.noResult
       (configDbPreparedStatements conf)

src/PostgREST/Query/QueryBuilder.hs

@@ -66,45 +66,43 @@ getSelectsJoins rr@(Node ReadPlan{select, relName, relToParent=Just rel, relAggA
     aliasOrName = pgFmtIdent $ fromMaybe relName relAlias
     aggAlias = pgFmtIdent relAggAlias
     correlatedSubquery sub al cond =
-      (if relJoinType == Just JTInner then "INNER" else "LEFT") <> " JOIN LATERAL ( " <> sub <> " ) AS " <> SQL.sql al <> " ON " <> cond
+      (if relJoinType == Just JTInner then "INNER" else "LEFT") <> " JOIN LATERAL ( " <> sub <> " ) AS " <> al <> " ON " <> cond
     (sel, joi) = if relIsToOne rel
       then
         ( if relIsSpread
-            then SQL.sql aggAlias <> ".*"
+            then aggAlias <> ".*"
-            else SQL.sql ("row_to_json(" <> aggAlias <> ".*) AS " <> aliasOrName)
+            else "row_to_json(" <> aggAlias <> ".*) AS " <> aliasOrName
         , correlatedSubquery subquery aggAlias "TRUE")
       else
-        ( SQL.sql $ "COALESCE( " <> aggAlias <> "." <> aggAlias <> ", '[]') AS " <> aliasOrName
+        ( "COALESCE( " <> aggAlias <> "." <> aggAlias <> ", '[]') AS " <> aliasOrName
         , correlatedSubquery (
-            "SELECT json_agg(" <> SQL.sql aggAlias <> ") AS " <> SQL.sql aggAlias <>
+            "SELECT json_agg(" <> aggAlias <> ") AS " <> aggAlias <>
-            "FROM (" <> subquery <> " ) AS " <> SQL.sql aggAlias
+            "FROM (" <> subquery <> " ) AS " <> aggAlias
-          ) aggAlias $ if relJoinType == Just JTInner then SQL.sql aggAlias <> " IS NOT NULL" else "TRUE")
+          ) aggAlias $ if relJoinType == Just JTInner then aggAlias <> " IS NOT NULL" else "TRUE")
   in
   (if null select && null forest then selects else sel:selects, joi:joins)
 
 mutatePlanToQuery :: MutatePlan -> SQL.Snippet
 mutatePlanToQuery (Insert mainQi iCols body onConflct putConditions returnings _ applyDefaults) =
-  "INSERT INTO " <> SQL.sql (fromQi mainQi) <> SQL.sql (if null iCols then " " else "(" <> cols <> ") ") <>
+  "INSERT INTO " <> fromQi mainQi <> (if null iCols then " " else "(" <> cols <> ") ") <>
   fromJsonBodyF body iCols True False applyDefaults <>
   -- Only used for PUT
   (if null putConditions then mempty else "WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree (QualifiedIdentifier mempty "pgrst_body") <$> putConditions)) <>
-  SQL.sql (BS.unwords [
+  maybe mempty (\(oncDo, oncCols) ->
-    maybe mempty (\(oncDo, oncCols) ->
+    if null oncCols then
-      if null oncCols then
+      mempty
-        mempty
+    else
-      else
+      " ON CONFLICT(" <> intercalateSnippet ", " (pgFmtIdent <$> oncCols) <> ") " <> case oncDo of
-        " ON CONFLICT(" <> BS.intercalate ", " (pgFmtIdent <$> oncCols) <> ") " <> case oncDo of
+      IgnoreDuplicates ->
-        IgnoreDuplicates ->
+        "DO NOTHING"
-          "DO NOTHING"
+      MergeDuplicates  ->
-        MergeDuplicates  ->
+        if null iCols
-          if null iCols
+           then "DO NOTHING"
-             then "DO NOTHING"
+           else "DO UPDATE SET " <> intercalateSnippet ", " ((pgFmtIdent . tfName) <> const " = EXCLUDED." <> (pgFmtIdent . tfName) <$> iCols)
-             else "DO UPDATE SET " <> BS.intercalate ", " ((pgFmtIdent . tfName) <> const " = EXCLUDED." <> (pgFmtIdent . tfName) <$> iCols)
+    ) onConflct <> " " <>
-      ) onConflct,
+  returningF mainQi returnings
-    returningF mainQi returnings
-    ])
   where
-    cols = BS.intercalate ", " $ pgFmtIdent . tfName <$> iCols
+    cols = intercalateSnippet ", " $ pgFmtIdent . tfName <$> iCols
 
 -- An update without a limit is always filtered with a WHERE
 mutatePlanToQuery (Update mainQi uCols body logicForest range ordts returnings applyDefaults)
@@ -112,54 +110,54 @@ mutatePlanToQuery (Update mainQi uCols body logicForest range ordts returnings a
     -- if there are no columns we cannot do UPDATE table SET {empty}, it'd be invalid syntax
     -- selecting an empty resultset from mainQi gives us the column names to prevent errors when using &select=
     -- the select has to be based on "returnings" to make computed overloaded functions not throw
-    SQL.sql $ "SELECT " <> emptyBodyReturnedColumns <> " FROM " <> fromQi mainQi <> " WHERE false"
+    "SELECT " <> emptyBodyReturnedColumns <> " FROM " <> fromQi mainQi <> " WHERE false"
 
   | range == allRange =
-    "UPDATE " <> mainTbl <> " SET " <> SQL.sql nonRangeCols <> " " <>
+    "UPDATE " <> mainTbl <> " SET " <> nonRangeCols <> " " <>
     fromJsonBodyF body uCols False False applyDefaults <>
     whereLogic <> " " <>
-    SQL.sql (returningF mainQi returnings)
+    returningF mainQi returnings
 
   | otherwise =
     "WITH " <>
     "pgrst_update_body AS (" <> fromJsonBodyF body uCols True True applyDefaults <> "), " <>
     "pgrst_affected_rows AS (" <>
-      "SELECT " <> SQL.sql rangeIdF <> " FROM " <> mainTbl <>
+      "SELECT " <> rangeIdF <> " FROM " <> mainTbl <>
       whereLogic <> " " <>
       orderF mainQi ordts <> " " <>
       limitOffsetF range <>
     ") " <>
-    "UPDATE " <> mainTbl <> " SET " <> SQL.sql rangeCols <>
+    "UPDATE " <> mainTbl <> " SET " <> rangeCols <>
     "FROM pgrst_affected_rows " <>
-    "WHERE " <> SQL.sql whereRangeIdF <> " " <>
+    "WHERE " <> whereRangeIdF <> " " <>
-    SQL.sql (returningF mainQi returnings)
+    returningF mainQi returnings
 
   where
     whereLogic = if null logicForest then mempty else " WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)
-    mainTbl = SQL.sql (fromQi mainQi)
+    mainTbl = fromQi mainQi
-    emptyBodyReturnedColumns = if null returnings then "NULL" else BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName mainQi) <$> returnings)
+    emptyBodyReturnedColumns = if null returnings then "NULL" else intercalateSnippet ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName mainQi) <$> returnings)
-    nonRangeCols = BS.intercalate ", " (pgFmtIdent . tfName <> const " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_body") . tfName <$> uCols)
+    nonRangeCols = intercalateSnippet ", " (pgFmtIdent . tfName <> const " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_body") . tfName <$> uCols)
-    rangeCols = BS.intercalate ", " ((\col -> pgFmtIdent (tfName col) <> " = (SELECT " <> pgFmtIdent (tfName col) <> " FROM pgrst_update_body) ") <$> uCols)
+    rangeCols = intercalateSnippet ", " ((\col -> pgFmtIdent (tfName col) <> " = (SELECT " <> pgFmtIdent (tfName col) <> " FROM pgrst_update_body) ") <$> uCols)
     (whereRangeIdF, rangeIdF) = mutRangeF mainQi (fst . otTerm <$> ordts)
 
 mutatePlanToQuery (Delete mainQi logicForest range ordts returnings)
   | range == allRange =
-    "DELETE FROM " <> SQL.sql (fromQi mainQi) <> " " <>
+    "DELETE FROM " <> fromQi mainQi <> " " <>
     whereLogic <> " " <>
-    SQL.sql (returningF mainQi returnings)
+    returningF mainQi returnings
 
   | otherwise =
     "WITH " <>
     "pgrst_affected_rows AS (" <>
-      "SELECT " <> SQL.sql rangeIdF <> " FROM " <> SQL.sql (fromQi mainQi) <>
+      "SELECT " <> rangeIdF <> " FROM " <> fromQi mainQi <>
        whereLogic <> " " <>
       orderF mainQi ordts <> " " <>
       limitOffsetF range <>
     ") " <>
-    "DELETE FROM " <> SQL.sql (fromQi mainQi) <> " " <>
+    "DELETE FROM " <> fromQi mainQi <> " " <>
     "USING pgrst_affected_rows " <>
-    "WHERE " <> SQL.sql whereRangeIdF <> " " <>
+    "WHERE " <> whereRangeIdF <> " " <>
-    SQL.sql (returningF mainQi returnings)
+    returningF mainQi returnings
 
   where
     whereLogic = if null logicForest then mempty else " WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)
@@ -177,17 +175,17 @@ callPlanToQuery (FunctionCall qi params args returnsScalar returnsSetOfScalar re
                          "LATERAL " <> callIt (fmtParams prms)
 
     callIt :: SQL.Snippet -> SQL.Snippet
-    callIt argument | pgVer < pgVersion130 && pgVer >= pgVersion110 && returnsCompositeAlias = "(SELECT (" <> SQL.sql (fromQi qi) <> "(" <> argument <> ")).*) pgrst_call"
+    callIt argument | pgVer < pgVersion130 && pgVer >= pgVersion110 && returnsCompositeAlias = "(SELECT (" <> fromQi qi <> "(" <> argument <> ")).*) pgrst_call"
-                    | otherwise                                                              = SQL.sql (fromQi qi) <> "(" <> argument <> ") pgrst_call"
+                    | otherwise                                                              = fromQi qi <> "(" <> argument <> ") pgrst_call"
 
     fmtParams :: [RoutineParam] -> SQL.Snippet
-    fmtParams prms = SQL.sql $ BS.intercalate ", "
+    fmtParams prms = intercalateSnippet ", "
       ((\a -> (if ppVar a then "VARIADIC " else mempty) <> pgFmtIdent (ppName a) <> " := pgrst_body." <> pgFmtIdent (ppName a)) <$> prms)
 
     returnedColumns :: SQL.Snippet
     returnedColumns
       | null returnings = "*"
-      | otherwise       = SQL.sql $ BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty "pgrst_call") <$> returnings)
+      | otherwise       = intercalateSnippet ", " (pgFmtColumn (QualifiedIdentifier mempty "pgrst_call") <$> returnings)
 
 -- | SQL query meant for COUNTing the root node of the Tree.
 -- It only takes WHERE into account and doesn't include LIMIT/OFFSET because it would reduce the COUNT.
@@ -229,7 +227,7 @@ getQualifiedIdentifier rel mainQi tblAlias = case rel of
 
 -- FROM clause plus implicit joins
 fromF :: Maybe Relationship -> QualifiedIdentifier -> Maybe Alias -> SQL.Snippet
-fromF rel mainQi tblAlias = SQL.sql $ "FROM " <>
+fromF rel mainQi tblAlias = "FROM " <>
   (case rel of
     Just ComputedRelationship{relFunction,relTable} -> fromQi relFunction <> "(" <> pgFmtIdent (qiName relTable) <> ")"
     _                                               -> fromQi mainQi) <>

src/PostgREST/Query/SqlFragment.hs

@@ -4,12 +4,9 @@
 {-|
 Module      : PostgREST.Query.SqlFragment
 Description : Helper functions for PostgREST.QueryBuilder.
-
-Any function that outputs a SqlFragment should be in this module.
 -}
 module PostgREST.Query.SqlFragment
   ( noLocationF
-  , SqlFragment
   , asBinaryF
   , asCsvF
   , asGeoJsonF
@@ -24,7 +21,6 @@ module PostgREST.Query.SqlFragment
   , orderF
   , pgFmtColumn
   , pgFmtIdent
-  , pgFmtIdentList
   , pgFmtJoinCondition
   , pgFmtLogicTree
   , pgFmtOrderTerm
@@ -34,12 +30,15 @@ module PostgREST.Query.SqlFragment
   , responseStatusF
   , returningF
   , singleParameter
+  , sourceCTE
   , sourceCTEName
   , unknownEncoder
   , intercalateSnippet
   , explainF
   , setConfigLocal
   , setConfigLocalJson
+  , escapeIdent
+  , escapeIdentList
   ) where
 
 import qualified Data.Aeson                      as JSON
@@ -87,17 +86,16 @@ import PostgREST.SchemaCache.Routine     (Routine (..),
 
 import Protolude hiding (cast)
 
-
+sourceCTEName :: Text
--- | A part of a SQL query that cannot be executed independently
-type SqlFragment = ByteString
-
-noLocationF :: SqlFragment
-noLocationF = "array[]::text[]"
-
-sourceCTEName :: SqlFragment
 sourceCTEName = "pgrst_source"
 
-simpleOperator :: SimpleOperator -> SqlFragment
+sourceCTE :: SQL.Snippet
+sourceCTE = "pgrst_source"
+
+noLocationF :: SQL.Snippet
+noLocationF = "array[]::text[]"
+
+simpleOperator :: SimpleOperator -> SQL.Snippet
 simpleOperator = \case
   OpNotEqual        -> "<>"
   OpContains        -> "@>"
@@ -109,7 +107,7 @@ simpleOperator = \case
   OpNotExtendsLeft  -> "&>"
   OpAdjacent        -> "-|-"
 
-quantOperator :: QuantOperator -> SqlFragment
+quantOperator :: QuantOperator -> SQL.Snippet
 quantOperator = \case
   OpEqual            -> "="
   OpGreaterThanEqual -> ">="
@@ -121,7 +119,7 @@ quantOperator = \case
   OpMatch            -> "~"
   OpIMatch           -> "~*"
 
-ftsOperator :: FtsOperator -> SqlFragment
+ftsOperator :: FtsOperator -> SQL.Snippet
 ftsOperator = \case
   FilterFts          -> "@@ to_tsquery"
   FilterFtsPlain     -> "@@ plainto_tsquery"
@@ -149,8 +147,11 @@ pgBuildArrayLiteral vals =
  "{" <> T.intercalate "," (escaped <$> vals) <> "}"
 
 -- TODO: refactor by following https://github.com/PostgREST/postgrest/pull/1631#issuecomment-711070833
-pgFmtIdent :: Text -> SqlFragment
+pgFmtIdent :: Text -> SQL.Snippet
-pgFmtIdent x = encodeUtf8 $ "\"" <> T.replace "\"" "\"\"" (trimNullChars x) <> "\""
+pgFmtIdent x = SQL.sql $ escapeIdent x
+
+escapeIdent :: Text -> ByteString
+escapeIdent x = encodeUtf8 $ "\"" <> T.replace "\"" "\"\"" (trimNullChars x) <> "\""
 
 -- Only use it if the input comes from the database itself, like on `jsonb_build_object('column_from_a_table', val)..`
 pgFmtLit :: Text -> Text
@@ -168,12 +169,12 @@ trimNullChars = T.takeWhile (/= '\x0')
 -- |
 -- Format a list of identifiers and separate them by commas.
 --
--- >>> pgFmtIdentList ["schema_1", "schema_2", "SPECIAL \"@/\\#~_-"]
+-- >>> escapeIdentList ["schema_1", "schema_2", "SPECIAL \"@/\\#~_-"]
 -- "\"schema_1\", \"schema_2\", \"SPECIAL \"\"@/\\#~_-\""
-pgFmtIdentList :: [Text] -> SqlFragment
+escapeIdentList :: [Text] -> ByteString
-pgFmtIdentList schemas = BS.intercalate ", " $ pgFmtIdent <$> schemas
+escapeIdentList schemas = BS.intercalate ", " $ escapeIdent <$> schemas
 
-asCsvF :: SqlFragment
+asCsvF :: SQL.Snippet
 asCsvF = asCsvHeaderF <> " || '\n' || " <> asCsvBodyF
   where
     asCsvHeaderF =
@@ -181,20 +182,20 @@ asCsvF = asCsvHeaderF <> " || '\n' || " <> asCsvBodyF
       "  FROM (" <>
       "    SELECT json_object_keys(r)::text as k" <>
       "    FROM ( " <>
-      "      SELECT row_to_json(hh) as r from " <> sourceCTEName <> " as hh limit 1" <>
+      "      SELECT row_to_json(hh) as r from " <> sourceCTE <> " as hh limit 1" <>
       "    ) s" <>
       "  ) a" <>
       ")"
     asCsvBodyF = "coalesce(string_agg(substring(_postgrest_t::text, 2, length(_postgrest_t::text) - 2), '\n'), '')"
 
-asJsonSingleF :: Maybe Routine -> SqlFragment
+asJsonSingleF :: Maybe Routine -> SQL.Snippet
 asJsonSingleF rout
   | returnsScalar = "coalesce(json_agg(_postgrest_t.pgrst_scalar)->0, 'null')"
   | otherwise     = "coalesce(json_agg(_postgrest_t)->0, 'null')"
   where
     returnsScalar = maybe False funcReturnsScalar rout
 
-asJsonF :: Maybe Routine -> SqlFragment
+asJsonF :: Maybe Routine -> SQL.Snippet
 asJsonF rout
   | returnsSingleComposite              = "coalesce(json_agg(_postgrest_t)->0, 'null')"
   | returnsScalar                       = "coalesce(json_agg(_postgrest_t.pgrst_scalar)->0, 'null')"
@@ -205,16 +206,16 @@ asJsonF rout
       Just r  -> (funcReturnsSingleComposite r, funcReturnsScalar r, funcReturnsSetOfScalar r)
       Nothing -> (False, False, False)
 
-asXmlF :: FieldName -> SqlFragment
+asXmlF :: FieldName -> SQL.Snippet
 asXmlF fieldName = "coalesce(xmlagg(_postgrest_t." <> pgFmtIdent fieldName <> "), '')"
 
-asGeoJsonF ::  SqlFragment
+asGeoJsonF ::  SQL.Snippet
 asGeoJsonF = "json_build_object('type', 'FeatureCollection', 'features', coalesce(json_agg(ST_AsGeoJSON(_postgrest_t)::json), '[]'))"
 
-asBinaryF :: FieldName -> SqlFragment
+asBinaryF :: FieldName -> SQL.Snippet
 asBinaryF fieldName = "coalesce(string_agg(_postgrest_t." <> pgFmtIdent fieldName <> ", ''), '')"
 
-locationF :: [Text] -> SqlFragment
+locationF :: [Text] -> SQL.Snippet
 locationF pKeys = [qc|(
   WITH data AS (SELECT row_to_json(_) AS row FROM {sourceCTEName} AS _ LIMIT 1)
   SELECT array_agg(json_data.key || '=' || coalesce('eq.' || json_data.value, 'is.null'))
@@ -224,33 +225,32 @@ locationF pKeys = [qc|(
   where
     fmtPKeys = T.intercalate "','" pKeys
 
-fromQi :: QualifiedIdentifier -> SqlFragment
+fromQi :: QualifiedIdentifier -> SQL.Snippet
 fromQi t = (if T.null s then mempty else pgFmtIdent s <> ".") <> pgFmtIdent n
   where
     n = qiName t
     s = qiSchema t
 
-pgFmtColumn :: QualifiedIdentifier -> Text -> SqlFragment
+pgFmtColumn :: QualifiedIdentifier -> Text -> SQL.Snippet
 pgFmtColumn table "*" = fromQi table <> ".*"
 pgFmtColumn table c   = fromQi table <> "." <> pgFmtIdent c
 
 pgFmtField :: QualifiedIdentifier -> Field -> SQL.Snippet
-pgFmtField table (c, []) = SQL.sql (pgFmtColumn table c)
+pgFmtField table (c, []) = pgFmtColumn table c
 -- Using to_jsonb instead of to_json to avoid missing operator errors when filtering:
 -- "operator does not exist: json = unknown"
-pgFmtField table (c, jp) = SQL.sql ("to_jsonb(" <> pgFmtColumn table c <> ")") <> pgFmtJsonPath jp
+pgFmtField table (c, jp) = "to_jsonb(" <> pgFmtColumn table c <> ")" <> pgFmtJsonPath jp
 
 pgFmtSelectItem :: QualifiedIdentifier -> (Field, Maybe Cast, Maybe Alias) -> SQL.Snippet
-pgFmtSelectItem table (f@(fName, jp), Nothing, alias) = pgFmtField table f <> SQL.sql (pgFmtAs fName jp alias)
+pgFmtSelectItem table (f@(fName, jp), Nothing, alias) = pgFmtField table f <> pgFmtAs fName jp alias
 -- Ideally we'd quote the cast with "pgFmtIdent cast". However, that would invalidate common casts such as "int", "bigint", etc.
 -- 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.
 -- Not quoting should be fine, we validate the input on Parsers.
-pgFmtSelectItem table (f@(fName, jp), Just cast, alias) = "CAST (" <> pgFmtField table f <> " AS " <> SQL.sql (encodeUtf8 cast) <> " )" <> SQL.sql (pgFmtAs fName jp alias)
+pgFmtSelectItem table (f@(fName, jp), Just cast, alias) = "CAST (" <> pgFmtField table f <> " AS " <> SQL.sql (encodeUtf8 cast) <> " )" <> pgFmtAs fName jp alias
 
 -- TODO: At this stage there shouldn't be a Maybe since ApiRequest should ensure that an INSERT/UPDATE has a body
 fromJsonBodyF :: Maybe LBS.ByteString -> [TypedField] -> Bool -> Bool -> Bool -> SQL.Snippet
 fromJsonBodyF body fields includeSelect includeLimitOne includeDefaults =
-  SQL.sql
   (if includeSelect then "SELECT " <> parsedCols <> " " else mempty) <>
   "FROM (SELECT " <> jsonPlaceHolder <> " AS json_data) pgrst_payload, " <>
   -- convert a json object into a json array, this way we can use json_to_recordset for all json payloads
@@ -266,12 +266,12 @@ fromJsonBodyF body fields includeSelect includeLimitOne includeDefaults =
       -- because it can't extract records with no columns (there's no valid syntax for the `AS (colName colType,...)`
       -- part). But we still need to ensure as many rows are created as there are array elements.
       then SQL.sql $ jsonArrayElementsF <> "(" <> finalBodyF <> ") _ "
-      else SQL.sql $ jsonToRecordsetF <> "(" <> finalBodyF <> ") AS _(" <> typedCols <> ") " <> if includeLimitOne then "LIMIT 1" else mempty
+      else jsonToRecordsetF <> "(" <> SQL.sql finalBodyF <> ") AS _(" <> typedCols <> ") " <> if includeLimitOne then "LIMIT 1" else mempty
     ) <>
   ") pgrst_body "
   where
-    parsedCols = BS.intercalate ", " $ fromQi  . QualifiedIdentifier "pgrst_body" . tfName <$> fields
+    parsedCols = intercalateSnippet ", " $ fromQi  . QualifiedIdentifier "pgrst_body" . tfName <$> fields
-    typedCols = BS.intercalate ", " $ pgFmtIdent . tfName <> const " " <> encodeUtf8 . tfIRType <$> fields
+    typedCols = intercalateSnippet ", " $ pgFmtIdent . tfName <> const " " <> SQL.sql . encodeUtf8 . tfIRType <$> fields
     defsJsonb = SQL.sql $ BS.intercalate "," fieldsWDefaults
     fieldsWDefaults = mapMaybe (\case
         TypedField{tfName=nam, tfDefault=Just def} -> Just $ encodeUtf8 (pgFmtLit nam <> ", " <> def)
@@ -302,12 +302,12 @@ pgFmtOrderTerm qi ot =
 
 
 pgFmtFilter :: QualifiedIdentifier -> Filter -> SQL.Snippet
-pgFmtFilter _ (FilterNullEmbed hasNot fld) = SQL.sql (pgFmtIdent fld) <> " IS " <> (if hasNot then "NOT" else mempty) <> " NULL"
+pgFmtFilter _ (FilterNullEmbed hasNot fld) = pgFmtIdent fld <> " IS " <> (if hasNot then "NOT" else mempty) <> " NULL"
 pgFmtFilter _ (Filter _ (NoOpExpr _)) = mempty -- TODO unreachable because NoOpExpr is filtered on QueryParams
 pgFmtFilter table (Filter fld (OpExpr hasNot oper)) = notOp <> " " <> pgFmtField table fld <> case oper of
-   Op op val -> " " <> SQL.sql (simpleOperator op) <> " " <> unknownLiteral val
+   Op op val -> " " <> simpleOperator op <> " " <> unknownLiteral val
 
-   OpQuant op quant val -> " " <> SQL.sql (quantOperator op) <> " " <> case op of
+   OpQuant op quant val -> " " <> quantOperator op <> " " <> case op of
      OpLike  -> fmtQuant quant $ unknownLiteral (T.map star val)
      OpILike -> fmtQuant quant $ unknownLiteral (T.map star val)
      _       -> fmtQuant quant $ unknownLiteral val
@@ -331,7 +331,7 @@ pgFmtFilter table (Filter fld (OpExpr hasNot oper)) = notOp <> " " <> pgFmtField
       [""] -> "= ANY('{}') "
       _    -> "= ANY (" <> unknownLiteral (pgBuildArrayLiteral vals) <> ") "
 
-   Fts op lang val -> " " <> SQL.sql (ftsOperator op) <> "(" <> ftsLang lang <> unknownLiteral val <> ") "
+   Fts op lang val -> " " <> ftsOperator op <> "(" <> ftsLang lang <> unknownLiteral val <> ") "
  where
    ftsLang = maybe mempty (\l -> unknownLiteral l <> ", ")
    notOp = if hasNot then "NOT" else mempty
@@ -343,7 +343,7 @@ pgFmtFilter table (Filter fld (OpExpr hasNot oper)) = notOp <> " " <> pgFmtField
 
 pgFmtJoinCondition :: JoinCondition -> SQL.Snippet
 pgFmtJoinCondition (JoinCondition (qi1, col1) (qi2, col2)) =
-  SQL.sql $ pgFmtColumn qi1 col1 <> " = " <> pgFmtColumn qi2 col2
+  pgFmtColumn qi1 col1 <> " = " <> pgFmtColumn qi2 col2
 
 pgFmtLogicTree :: QualifiedIdentifier -> LogicTree -> SQL.Snippet
 pgFmtLogicTree qi (Expr hasNot op forest) = SQL.sql notOp <> " (" <> intercalateSnippet (opSql op) (pgFmtLogicTree qi <$> forest) <> ")"
@@ -363,7 +363,7 @@ pgFmtJsonPath = \case
     pgFmtJsonOperand (JKey k) = unknownLiteral k
     pgFmtJsonOperand (JIdx i) = unknownLiteral i <> "::int"
 
-pgFmtAs :: FieldName -> JsonPath -> Maybe Alias -> SqlFragment
+pgFmtAs :: FieldName -> JsonPath -> Maybe Alias -> SQL.Snippet
 pgFmtAs _ [] Nothing = mempty
 pgFmtAs fName jp Nothing = case jOp <$> lastMay jp of
   Just (JKey key) -> " AS " <> pgFmtIdent key
@@ -375,7 +375,7 @@ pgFmtAs fName jp Nothing = case jOp <$> lastMay jp of
   Nothing -> mempty
 pgFmtAs _ _ (Just alias) = " AS " <> pgFmtIdent alias
 
-countF :: SQL.Snippet -> Bool -> (SQL.Snippet, SqlFragment)
+countF :: SQL.Snippet -> Bool -> (SQL.Snippet, SQL.Snippet)
 countF countQuery shouldCount =
   if shouldCount
     then (
@@ -385,11 +385,11 @@ countF countQuery shouldCount =
         mempty
       , "null::bigint")
 
-returningF :: QualifiedIdentifier -> [FieldName] -> SqlFragment
+returningF :: QualifiedIdentifier -> [FieldName] -> SQL.Snippet
 returningF qi returnings =
   if null returnings
     then "RETURNING 1" -- For mutation cases where there's no ?select, we return 1 to know how many rows were modified
-    else "RETURNING " <> BS.intercalate ", " (pgFmtColumn qi <$> returnings)
+    else "RETURNING " <> intercalateSnippet ", " (pgFmtColumn qi <$> returnings)
 
 limitOffsetF :: NonnegRange -> SQL.Snippet
 limitOffsetF range =
@@ -398,22 +398,22 @@ limitOffsetF range =
     limit = maybe "ALL" (\l -> unknownEncoder (BS.pack $ show l)) $ rangeLimit range
     offset = unknownEncoder (BS.pack . show $ rangeOffset range)
 
-responseHeadersF :: SqlFragment
+responseHeadersF :: SQL.Snippet
 responseHeadersF = currentSettingF "response.headers"
 
-responseStatusF :: SqlFragment
+responseStatusF :: SQL.Snippet
 responseStatusF = currentSettingF "response.status"
 
-currentSettingF :: SqlFragment -> SqlFragment
+currentSettingF :: SQL.Snippet -> SQL.Snippet
 currentSettingF setting =
   -- nullif is used because of https://gist.github.com/steve-chavez/8d7033ea5655096903f3b52f8ed09a15
   "nullif(current_setting('" <> setting <> "', true), '')"
 
-mutRangeF :: QualifiedIdentifier -> [FieldName] -> (SqlFragment, SqlFragment)
+mutRangeF :: QualifiedIdentifier -> [FieldName] -> (SQL.Snippet, SQL.Snippet)
 mutRangeF mainQi rangeId =
   (
-    BS.intercalate " AND " $ (\col -> pgFmtColumn mainQi col <> " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_affected_rows") col) <$> rangeId
+    intercalateSnippet " AND " $ (\col -> pgFmtColumn mainQi col <> " = " <> pgFmtColumn (QualifiedIdentifier mempty "pgrst_affected_rows") col) <$> rangeId
-  , BS.intercalate ", " (pgFmtColumn mainQi <$> rangeId)
+  , intercalateSnippet ", " (pgFmtColumn mainQi <$> rangeId)
   )
 
 orderF :: QualifiedIdentifier -> [OrderTerm] -> SQL.Snippet

src/PostgREST/Query/Statements.hs

@@ -61,25 +61,23 @@ prepareWrite selectQuery mutateQuery isInsert mt rep pKeys =
   SQL.dynamicallyParameterized (mtSnippet mt snippet) decodeIt
  where
   snippet =
-    "WITH " <> SQL.sql sourceCTEName <> " AS (" <> mutateQuery <> ") " <>
+    "WITH " <> sourceCTE <> " AS (" <> mutateQuery <> ") " <>
-    SQL.sql (
     "SELECT " <>
       "'' AS total_result_set, " <>
       "pg_catalog.count(_postgrest_t) AS page_total, " <>
       locF <> " AS header, " <>
       bodyF <> " AS body, " <>
       responseHeadersF <> " AS response_headers, " <>
-      responseStatusF  <> " AS response_status "
+      responseStatusF  <> " AS response_status " <>
-    ) <>
     "FROM (" <> selectF <> ") _postgrest_t"
 
   locF =
     if isInsert && rep == HeadersOnly
-      then BS.unwords [
+      then
-        "CASE WHEN pg_catalog.count(_postgrest_t) = 1",
+        "CASE WHEN pg_catalog.count(_postgrest_t) = 1 " <>
-          "THEN coalesce(" <> locationF pKeys <> ", " <> noLocationF <> ")",
+          "THEN coalesce(" <> locationF pKeys <> ", " <> noLocationF <> ") " <>
-          "ELSE " <> noLocationF,
+          "ELSE " <> noLocationF <> " " <>
-        "END"]
+        "END"
       else noLocationF
 
   bodyF
@@ -91,7 +89,7 @@ prepareWrite selectQuery mutateQuery isInsert mt rep pKeys =
 
   selectF
     -- prevent using any of the column names in ?select= when no response is returned from the CTE
-    | rep /= Full = SQL.sql ("SELECT * FROM " <> sourceCTEName)
+    | rep /= Full = "SELECT * FROM " <> sourceCTE
     | otherwise   = selectQuery
 
   decodeIt :: HD.Result ResultSet
@@ -104,16 +102,15 @@ prepareRead selectQuery countQuery countTotal mt binaryField =
   SQL.dynamicallyParameterized (mtSnippet mt snippet) decodeIt
  where
   snippet =
-    "WITH " <>
+    "WITH " <> sourceCTE <> " AS ( " <> selectQuery <> " ) " <>
-    SQL.sql sourceCTEName <> " AS ( " <> selectQuery <> " ) " <>
     countCTEF <> " " <>
-    SQL.sql ("SELECT " <>
+    "SELECT " <>
       countResultF <> " AS total_result_set, " <>
       "pg_catalog.count(_postgrest_t) AS page_total, " <>
       bodyF <> " AS body, " <>
       responseHeadersF <> " AS response_headers, " <>
       responseStatusF <> " AS response_status " <>
-    "FROM ( SELECT * FROM " <> sourceCTEName <> " ) _postgrest_t")
+    "FROM ( SELECT * FROM " <> sourceCTE <> " ) _postgrest_t"
 
   (countCTEF, countResultF) = countF countQuery countTotal
 
@@ -137,15 +134,14 @@ prepareCall rout callProcQuery selectQuery countQuery countTotal mt binaryField
   SQL.dynamicallyParameterized (mtSnippet mt snippet) decodeIt
   where
     snippet =
-      "WITH " <> SQL.sql sourceCTEName <> " AS (" <> callProcQuery <> ") " <>
+      "WITH " <> sourceCTE <> " AS (" <> callProcQuery <> ") " <>
       countCTEF <>
-      SQL.sql (
       "SELECT " <>
         countResultF <> " AS total_result_set, " <>
         "pg_catalog.count(_postgrest_t) AS page_total, " <>
         bodyF <> " AS body, " <>
         responseHeadersF <> " AS response_headers, " <>
-        responseStatusF <> " AS response_status ") <>
+        responseStatusF <> " AS response_status " <>
       "FROM (" <> selectQuery <> ") _postgrest_t"
 
     (countCTEF, countResultF) = countF countQuery countTotal