refactor: runPgLocals to Query.hs

* unmmiddleware runPgLocals

src/PostgREST/Query/SqlFragment.hs

@@ -38,14 +38,21 @@ module PostgREST.Query.SqlFragment
   , unknownEncoder
   , intercalateSnippet
   , explainF
+  , setConfigLocal
+  , setConfigLocalJson
   ) where
 
+import qualified Data.Aeson                      as JSON
 import qualified Data.ByteString.Char8           as BS
 import qualified Data.ByteString.Lazy            as LBS
+import qualified Data.HashMap.Strict             as HM
 import qualified Data.Text                       as T
+import qualified Data.Text.Encoding              as T
 import qualified Hasql.DynamicStatements.Snippet as SQL
 import qualified Hasql.Encoders                  as HE
 
+import Control.Arrow ((***))
+
 import Data.Foldable                 (foldr1)
 import Text.InterpolatedString.Perl6 (qc)
 
@@ -386,3 +393,18 @@ explainF fmt opts snip =
 
     fmtPlanFmt PlanJSON = "FORMAT JSON"
     fmtPlanFmt PlanText = "FORMAT TEXT"
+
+-- | Do a pg set_config(setting, value, true) call. This is equivalent to a SET LOCAL.
+setConfigLocal :: ByteString -> (ByteString, ByteString) -> SQL.Snippet
+setConfigLocal prefix (k, v) =
+  "set_config(" <> unknownEncoder (prefix <> k) <> ", " <> unknownEncoder v <> ", true)"
+
+-- | Starting from PostgreSQL v14, some characters are not allowed for config names (mostly affecting headers with "-").
+-- | A JSON format string is used to avoid this problem. See https://github.com/PostgREST/postgrest/issues/1857
+setConfigLocalJson :: ByteString -> [(ByteString, ByteString)] -> [SQL.Snippet]
+setConfigLocalJson prefix keyVals = [setConfigLocal mempty (prefix, gucJsonVal keyVals)]
+  where
+    gucJsonVal :: [(ByteString, ByteString)] -> ByteString
+    gucJsonVal = LBS.toStrict . JSON.encode . HM.fromList . arrayByteStringToText
+    arrayByteStringToText :: [(ByteString, ByteString)] -> [(Text,Text)]
+    arrayByteStringToText keyVal = (T.decodeUtf8 *** T.decodeUtf8) <$> keyVal