Handle headers properly when 2nd row in a CSV file is broken

Author: ozataman

src/Data/CSV/Enumerator.hs

@@ -362,19 +362,19 @@ appendCSVFile :: (CSVeable r) => CSVSettings -- ^ CSV settings
  -> [r] -- ^ Data to be output
  -> IO Int -- ^ Number of rows written
 appendCSVFile s fp rs = 
- let doOutput (c,h) = when c (writeHeaders s h rs) >> outputRowsIter h
+ let doOutput (c,h) = when c (writeHeaders s h rs >> return ()) >> outputRowsIter h
  outputRowsIter h = foldM (step h) 0 . map (rowToStr s) $ rs
  step h acc x = (B.hPutStrLn h x) >> return (acc+1)
  chkOpen = do
- writeHeaders <- do
+ wrHeader <- do
  fe <- doesFileExist fp 
  if fe
- then do
-  fs <- getFileStatus fp >>= return . fileSize
-  return $ if fs > 0 then False else True
+  then do
+   fs <- getFileStatus fp >>= return . fileSize
+   return $ if fs > 0 then False else True
  else return True
  h <- openFile fp AppendMode
- return (writeHeaders, h)
+ return (wrHeader, h)
  in bracket
  (chkOpen)
  (hClose . snd)
@@ -405,10 +405,10 @@ outputColumns s h cs r = outputRow s h r'
 
 
 
-writeHeaders :: CSVeable r => CSVSettings -> Handle -> [r] -> IO ()
+writeHeaders :: CSVeable r => CSVSettings -> Handle -> [r] -> IO Bool
 writeHeaders s h rs = case fileHeaders rs of
- Just hs -> B.hPutStrLn h . rowToStr s $ hs
- Nothing -> return ()
+ Just hs -> (B.hPutStrLn h . rowToStr s) hs >> return True
+ Nothing -> return False
 
 
 outputRowIter :: CSVeable r => CSVSettings -> Handle -> r -> E.Iteratee B.ByteString IO ()
@@ -493,10 +493,12 @@ mapIntoHandle csvs outh h f = do
  where
  f' acc EOF = return acc
  f' acc (ParsedRow Nothing) = return acc
- f' (False, _) r'@(ParsedRow (Just r)) = do
+ f' (False, i) r'@(ParsedRow (Just r)) = do
  rs <- f r
- when outh $ writeHeaders csvs h rs
- f' (True, 0) r'
+ headerDone <- if outh then writeHeaders csvs h rs else return True
+ if headerDone 
+ then f' (headerDone, 0) r' -- Headers are done, now process row
+ else return (False, i+1) -- Problem in this row, move on to next
  f' (True, !i) (ParsedRow (Just r)) = do
  rs <- f r
  outputRows csvs h rs