fix: bal: correctly handle empty commodity in commodity-column (#1654)

We can't filter out empty commodity strings since that is a legitimate
group. Simultaneously, we should only include the empty commodity if it
is explicitly used (part of a posting) and not generated as part of
`Amounts.amounts`

hledger-lib/Hledger/Data/Amount.hs

@@ -100,6 +100,7 @@ module Hledger.Data.Amount (
   maAddAmounts,
   amounts,
   amountsRaw,
+  maCommodities,
   filterMixedAmount,
   filterMixedAmountByCommodity,
   mapMixedAmount,
@@ -152,6 +153,7 @@ import Data.Foldable (toList)
 import Data.List (find, foldl', intercalate, intersperse, mapAccumL, partition)
 import Data.List.NonEmpty (NonEmpty(..), nonEmpty)
 import qualified Data.Map.Strict as M
+import qualified Data.Set as S
 import Data.Maybe (fromMaybe, isNothing, isJust)
 import Data.Semigroup (Semigroup(..))
 import qualified Data.Text as T
@@ -662,6 +664,11 @@ amounts (Mixed ma)
 amountsRaw :: MixedAmount -> [Amount]
 amountsRaw (Mixed ma) = toList ma
 
+-- | Get the set of mixed amount commodities. Returns an empty set of no amounts
+maCommodities :: MixedAmount -> S.Set CommoditySymbol
+maCommodities = S.fromList . fmap acommodity . amounts'
+  where amounts' ma@(Mixed m) = if M.null m then [] else amounts ma
+
 normaliseMixedAmount :: MixedAmount -> MixedAmount
 normaliseMixedAmount = id  -- XXX Remove
 

hledger-lib/Hledger/Reports/BudgetReport.hs

@@ -241,12 +241,12 @@ budgetReportAsText ropts@ReportOpts{..} budgetr = TB.toLazyText $
           ( textCell TopLeft rh
           , textsCell TopLeft cs : fmap (uncurry (showcell' cs)) cells)
       where
-        cs = filter (not . T.null) . S.toList . foldl' S.union mempty
+        cs = S.toList . foldl' S.union mempty
             . fmap (budgetCellCommodities . fst . snd) $ cells
 
     budgetCellCommodities :: BudgetCell -> S.Set CommoditySymbol
     budgetCellCommodities (am, bm) = f am `S.union` f bm
-      where f = S.fromList . fmap acommodity . amounts . fromMaybe nullmixedamt
+      where f = maybe mempty maCommodities
 
     displayTableWithWidths :: Table Text Text ((Int, Int, Int), BudgetDisplayCell)
     displayTableWithWidths = Table rh ch $ map (zipWith (,) widths) displaycells
@@ -436,10 +436,7 @@ budgetReportAsCsv
           . fmap (fromMaybe nullmixedamt)
           $ all
       where
-        cs = commodities $ catMaybes all
-        commodities = filter (not . T.null) . S.toList
-            . foldl' S.union mempty
-            . fmap (S.fromList . fmap acommodity . amounts)
+        cs = S.toList . foldl' S.union mempty . fmap maCommodities $ catMaybes all
         all = flattentuples as
             ++ concat [[rowtot, budgettot] | row_total_]
             ++ concat [[rowavg, budgetavg] | average_]

hledger/Hledger/Cli/Commands/Balance.hs

@@ -408,7 +408,7 @@ balanceReportAsCsv opts (items, total) =
     showName = accountNameDrop (drop_ opts)
     renderAmount amt = wbToText $ showMixedAmountB bopts amt
       where bopts = (balanceOpts False opts){displayOrder = order}
-            order = if commodity_column_ opts then Just (commodities [amt]) else Nothing
+            order = if commodity_column_ opts then Just (S.toList $ maCommodities amt) else Nothing
     sumAmounts mp am = M.insertWith (+) (acommodity am) am mp
 
 -- | Render a single-column balance report as plain text.
@@ -444,7 +444,7 @@ balanceReportAsText' opts ((items, total)) =
         , Cell TopLeft (fmap wbFromText cs)
         , Cell TopLeft (replicate (length damts - 1) mempty ++ [wbFromText dispname]) ]
       where dopts = (balanceOpts True opts){displayOrder=Just cs}
-            cs    = commodities [amt]
+            cs    = S.toList $ maCommodities amt
             dispname = T.replicate ((depth - 1) * 2) " " <> acctname
             damts = showMixedAmountLinesB dopts amt
     lines = fmap render items
@@ -528,7 +528,7 @@ multiBalanceReportAsCsv' opts@ReportOpts{..}
           $ all
       where
         bopts = balanceOpts False opts
-        cs = commodities $ rowtot : rowavg : as
+        cs = S.toList . foldl' S.union mempty $ fmap maCommodities $ rowtot : rowavg : as
         all = as
             ++ [rowtot | row_total_]
             ++ [rowavg | average_]
@@ -717,12 +717,7 @@ balanceReportTableAsText ropts@ReportOpts{..} =
             : fmap (Cell TopRight . showMixedAmountLinesB bopts{displayOrder = Just cs}) row)
       where
         bopts = balanceOpts True ropts
-        cs = commodities row
-
-commodities :: [MixedAmount] -> [CommoditySymbol]
-commodities = filter (not . T.null) . S.toList
-    . foldl' S.union mempty
-    . fmap (S.fromList . fmap acommodity . amounts)
+        cs = S.toList . foldl' S.union mempty $ fmap maCommodities row
 
 -- | Amount display options to use for balance reports
 balanceOpts :: Bool -> ReportOpts -> AmountDisplayOpts