remove misleadingly named emptyOnFalse and similar (#1803)

src/PostgREST/Private/Common.hs

@@ -33,9 +33,6 @@ param = HE.param . HE.nonNullable
 arrayParam :: HE.Value a -> HE.Params [a]
 arrayParam = param . HE.foldableArray . HE.nonNullable
 
-emptySnippetOnFalse :: H.Snippet -> Bool -> H.Snippet
-emptySnippetOnFalse val cond = if cond then mempty else val
-
 intercalateSnippet :: ByteString -> [H.Snippet] -> H.Snippet
 intercalateSnippet _ [] = mempty
 intercalateSnippet frag snippets = foldr1 (\a b -> a <> H.sql frag <> b) snippets

src/PostgREST/Private/QueryFragment.hs

@@ -120,9 +120,6 @@ fromQi t = (if T.null s then mempty else pgFmtIdent s <> ".") <> pgFmtIdent n
     n = qiName t
     s = qiSchema t
 
-emptyOnFalse :: SqlFragment -> Bool -> SqlFragment
-emptyOnFalse val cond = if cond then mempty else val
-
 pgFmtColumn :: QualifiedIdentifier -> Text -> SqlFragment
 pgFmtColumn table "*" = fromQi table <> ".*"
 pgFmtColumn table c   = fromQi table <> "." <> pgFmtIdent c
@@ -226,7 +223,7 @@ returningF qi returnings =
 
 limitOffsetF :: NonnegRange -> H.Snippet
 limitOffsetF range =
-  ("LIMIT " <> limit <> " OFFSET " <> offset) `emptySnippetOnFalse` (range == allRange)
+  if range == allRange then mempty else "LIMIT " <> limit <> " OFFSET " <> offset
   where
     limit = maybe "ALL" (\l -> unknownEncoder (BS.pack $ show l)) $ rangeLimit range
     offset = unknownEncoder (BS.pack . show $ rangeOffset range)

src/PostgREST/QueryBuilder.hs

@@ -38,9 +38,9 @@ readRequestToQuery (Node (Select colSelects mainQi tblAlias implJoins logicFores
   intercalateSnippet ", " ((pgFmtSelectItem qi <$> colSelects) ++ selects) <>
   "FROM " <> H.sql (BS.intercalate ", " (tabl : implJs)) <> " " <>
   intercalateSnippet " " joins <> " " <>
-  ("WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest ++ map pgFmtJoinCondition joinConditions_))
-    `emptySnippetOnFalse` (null logicForest && null joinConditions_) <> " " <>
-  (("ORDER BY " <> intercalateSnippet ", " (map (pgFmtOrderTerm qi) ordts)) `emptySnippetOnFalse` null ordts) <> " " <>
+  (if null logicForest && null joinConditions_ then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest ++ map pgFmtJoinCondition joinConditions_))
+  <> " " <>
+  (if null ordts then mempty else "ORDER BY " <> intercalateSnippet ", " (map (pgFmtOrderTerm qi) ordts)) <> " " <>
   limitOffsetF range
   where
     implJs = fromQi <$> implJoins
@@ -73,17 +73,20 @@ mutateRequestToQuery (Insert mainQi iCols body onConflct putConditions returning
   "SELECT " <> H.sql cols <> " " <>
   H.sql ("FROM json_populate_recordset (null::" <> fromQi mainQi <> ", " <> selectBody <> ") _ ") <>
   -- Only used for PUT
-  ("WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree (QualifiedIdentifier mempty "_") <$> putConditions)) `emptySnippetOnFalse` null putConditions <>
+  (if null putConditions then mempty else "WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree (QualifiedIdentifier mempty "_") <$> putConditions)) <>
   H.sql (BS.unwords [
-    maybe "" (\(oncDo, oncCols) -> (
-      "ON CONFLICT(" <> BS.intercalate ", " (pgFmtIdent <$> oncCols) <> ") " <> case oncDo of
-      IgnoreDuplicates ->
-        "DO NOTHING"
-      MergeDuplicates  ->
-        if S.null iCols
-           then "DO NOTHING"
-           else "DO UPDATE SET " <> BS.intercalate ", " (pgFmtIdent <> const " = EXCLUDED." <> pgFmtIdent <$> S.toList iCols)
-                                   ) `emptyOnFalse` null oncCols) onConflct,
+    maybe "" (\(oncDo, oncCols) ->
+      if null oncCols then
+        mempty
+      else
+        "ON CONFLICT(" <> BS.intercalate ", " (pgFmtIdent <$> oncCols) <> ") " <> case oncDo of
+        IgnoreDuplicates ->
+          "DO NOTHING"
+        MergeDuplicates  ->
+          if S.null iCols
+             then "DO NOTHING"
+             else "DO UPDATE SET " <> BS.intercalate ", " (pgFmtIdent <> const " = EXCLUDED." <> pgFmtIdent <$> S.toList iCols)
+      ) onConflct,
     returningF mainQi returnings
     ])
   where
@@ -98,7 +101,7 @@ mutateRequestToQuery (Update mainQi uCols body logicForest returnings) =
       "WITH " <> normalizedBody body <> " " <>
       "UPDATE " <> H.sql (fromQi mainQi) <> " SET " <> H.sql cols <> " " <>
       "FROM (SELECT * FROM json_populate_recordset (null::" <> H.sql (fromQi mainQi) <> " , " <> H.sql selectBody <> " )) _ " <>
-      ("WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)) `emptySnippetOnFalse` null logicForest <> " " <>
+      (if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (pgFmtLogicTree mainQi <$> logicForest)) <> " " <>
       H.sql (returningF mainQi returnings)
   where
     cols = BS.intercalate ", " (pgFmtIdent <> const " = _." <> pgFmtIdent <$> S.toList uCols)
@@ -108,7 +111,7 @@ mutateRequestToQuery (Update mainQi uCols body logicForest returnings) =
       | otherwise       = BS.intercalate ", " (pgFmtColumn (QualifiedIdentifier mempty $ qiName mainQi) <$> returnings)
 mutateRequestToQuery (Delete mainQi logicForest returnings) =
   "DELETE FROM " <> H.sql (fromQi mainQi) <> " " <>
-  ("WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree mainQi) logicForest)) `emptySnippetOnFalse` null logicForest <> " " <>
+  (if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree mainQi) logicForest)) <> " " <>
   H.sql (returningF mainQi returnings)
 
 requestToCallProcQuery :: QualifiedIdentifier -> [PgArg] -> Maybe PayloadJSON -> Bool -> Maybe PreferParameters -> [FieldName] -> H.Snippet
@@ -168,7 +171,7 @@ requestToCallProcQuery qi pgArgs pj returnsScalar preferParams returnings =
 readRequestToCountQuery :: ReadRequest -> H.Snippet
 readRequestToCountQuery (Node (Select{from=qi, where_=logicForest}, _) _) =
  "SELECT 1 " <> "FROM " <> H.sql (fromQi qi) <> " " <>
- ("WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest)) `emptySnippetOnFalse` null logicForest
+ if null logicForest then mempty else "WHERE " <> intercalateSnippet " AND " (map (pgFmtLogicTree qi) logicForest)
 
 limitedQuery :: H.Snippet -> Maybe Integer -> H.Snippet
 limitedQuery query maxRows = query <> H.sql (maybe mempty (\x -> " LIMIT " <> BS.pack (show x)) maxRows)