Allow using nulls order without explicit order direction, fix #552

src/PostgREST/Parsers.hs

@@ -137,13 +137,14 @@ pOrderTerm :: Parser OrderTerm
 pOrderTerm =
   try ( do
     c <- pFieldName
-    _ <- pDelimiter
-    d <- (string "asc" *> pure OrderAsc)
-         <|> (string "desc" *> pure OrderDesc)
+    d <- optionMaybe (try $ pDelimiter *> (
+               try(string "asc" *> pure OrderAsc)
+           <|> try(string "desc" *> pure OrderDesc)
+         ))
     nls <- optionMaybe (pDelimiter *> (
                  try(string "nullslast" *> pure OrderNullsLast)
              <|> try(string "nullsfirst" *> pure OrderNullsFirst)
            ))
     return $ OrderTerm c d nls
   )
-  <|> OrderTerm <$> (toS <$> pFieldName) <*> pure OrderAsc <*> pure Nothing
+  <|> OrderTerm <$> (toS <$> pFieldName) <*> pure Nothing <*> pure Nothing

src/PostgREST/QueryBuilder.hs

@@ -307,7 +307,7 @@ requestToQuery schema isParent (DbRead (Node (Select colSelects tbls conditions
             queryTerm :: OrderTerm -> Text
             queryTerm t = " "
                 <> toS (pgFmtColumn qi $ otTerm t) <> " "
-                <> show (otDirection t) <> " "
+                <> maybe "" show (otDirection t) <> " "
                 <> maybe "" show (otNullOrder t) <> " "
     (joins, selects) = foldr getQueryParts ([],[]) forest
 

src/PostgREST/Types.hs

@@ -78,7 +78,7 @@ instance Show OrderNulls where
 
 data OrderTerm = OrderTerm {
   otTerm      :: Text
-, otDirection :: OrderDirection
+, otDirection :: Maybe OrderDirection
 , otNullOrder :: Maybe OrderNulls
 } deriving (Show, Eq)