postgres-haskell
diff --git a/‎src/Database/PostgreSQL/Protocol/Decoders.hs
Lines changed: 7 additions & 2 deletions b/‎src/Database/PostgreSQL/Protocol/Decoders.hs
Lines changed: 7 additions & 2 deletions
diff --git a/‎src/Database/PostgreSQL/Protocol/Encoders.hs
Lines changed: 8 additions & 4 deletions b/‎src/Database/PostgreSQL/Protocol/Encoders.hs
Lines changed: 8 additions & 4 deletions
diff --git a/‎src/Database/PostgreSQL/Protocol/Types.hs
Lines changed: 4 additions & 2 deletions b/‎src/Database/PostgreSQL/Protocol/Types.hs
Lines changed: 4 additions & 2 deletions
@@ -51,8 +51,7 @@ decodeServerMessage = do
                                     >>= decodeCommandResult)
         'D' -> do
             columnCount <- fromIntegral <$> getInt16be
-            DataRow <$> V.replicateM columnCount
-                (getInt32be >>= getByteString . fromIntegral)
+            DataRow <$> V.replicateM columnCount decodeValue
         'I' -> pure EmptyQueryResponse
         'E' -> ErrorResponse <$>
             (getByteString (fromIntegral $ len - 4) >>= decodeErrorDesc)
@@ -72,6 +71,12 @@ decodeServerMessage = do
             rowsCount <- fromIntegral <$> getInt16be
             RowDescription <$> V.replicateM rowsCount decodeFieldDescription
 
+-- | Decodes a single data value. Length `-1` indicates a NULL column value.
+-- No value bytes follow in the NULL case.
+decodeValue :: Get B.ByteString
+decodeValue = fromIntegral <$> getInt32be >>= \n ->
+    if n == -1 then pure "" else getByteString n
+
 decodeTransactionStatus :: Get TransactionStatus
 decodeTransactionStatus =  getWord8 >>= \t ->
     case chr $ fromIntegral t of
 
@@ -36,10 +36,7 @@ encodeClientMessage (Bind (PortalName portalName) (StatementName stmtName)
         int16BE 1 <>
         encodeFormat paramFormat <>
         int16BE (fromIntegral $ V.length values) <>
-        -- TODO -
8000
1 indicates a NULL parameter value. No value bytes
-        -- follow in the NULL case.
-        fold ((\v -> int32BE (fromIntegral $ B.length v) <> byteString v)
-              <$> values) <>
+        fold (encodeValue <$> values) <>
         -- `1` means that the specified format code is applied to all
         -- result columns (if any)
         int16BE 1 <>
@@ -76,6 +73,13 @@ encodeClientMessage Sync
 encodeClientMessage Terminate
     = prependHeader 'X' mempty
 
+-- Encodes single data values. Length `-1` indicates a NULL parameter value.
+-- No value bytes follow in the NULL case.
+encodeValue :: B.ByteString -> Builder
+encodeValue v | B.null v = int32BE (-1)
+              | otherwise = int32BE (fromIntegral $ B.length v)
+                            <> byteString v
+
 encodeFormat :: Format -> Builder
 encodeFormat Text   = int16BE 0
 encodeFormat Binary = int16BE 1
 
@@ -102,7 +102,8 @@ data AuthResponse
 data ClientMessage
     = Bind PortalName StatementName
         Format                  -- parameter format code, one format for all
-        (Vector ByteString) -- the values of parameters
+        (Vector ByteString)     -- the values of parameters, the empty string
+                                -- is recognized as NULL
         Format                  -- to apply code to all result columns
     -- Postgres use one command `close` for closing both statements and
     -- portals, but we distinguish them
@@ -130,7 +131,8 @@ data ServerMessage
     | BindComplete
     | CloseComplete
     | CommandComplete CommandResult
-    | DataRow (Vector ByteString)
+    | DataRow (Vector ByteString)  -- an empty string should be recognized
+                                   -- as NULL
     | EmptyQueryResponse
     | ErrorResponse ErrorDesc
     | NoData