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Fix: Validate join columns before join execution (#118) #159

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Fix: Validate join columns before join execution (#118) #159

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18 changes: 18 additions & 0 deletions src/DataFrame/Operations/Join.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,21 @@ data JoinType
| RIGHT
| FULL_OUTER

validateJoinColumns :: [T.Text] -> DataFrame -> DataFrame -> ()
validateJoinColumns cs df1 df2 =
let
df1Cols = D.columnNames df1
df2Cols = D.columnNames df2

missingInDf1 = filter (`notElem` df1Cols) cs
missingInDf2 = filter (`notElem` df2Cols) cs

missing = missingInDf1 ++ missingInDf2
in
if not (null missing)
then error $ "Column not found: " <> show missing
else ()

{- | Join two dataframes using SQL join semantics.

Only inner join is implemented for now.
Expand Down Expand Up @@ -66,6 +81,7 @@ ghci> D.innerJoin ["key"] df other
innerJoin :: [T.Text] -> DataFrame -> DataFrame -> DataFrame
innerJoin cs right left =
let
_ = validateJoinColumns cs right left
-- Prepare Keys for the Right DataFrame
rightIndicesToGroup =
[c | (k, c) <- M.toList (D.columnIndices right), k `elem` cs]
Expand Down Expand Up @@ -170,6 +186,7 @@ leftJoin ::
[T.Text] -> DataFrame -> DataFrame -> DataFrame
leftJoin cs right left =
let
_ = validateJoinColumns cs right left
leftIndicesToGroup = M.elems $ M.filterWithKey (\k _ -> k `elem` cs) (D.columnIndices left)
leftRowRepresentations = D.computeRowHashes leftIndicesToGroup left
rightIndicesToGroup = M.elems $ M.filterWithKey (\k _ -> k `elem` cs) (D.columnIndices right)
Expand Down Expand Up @@ -250,6 +267,7 @@ fullOuterJoin ::
[T.Text] -> DataFrame -> DataFrame -> DataFrame
fullOuterJoin cs right left =
let
_ = validateJoinColumns cs right left
leftIndicesToGroup = M.elems $ M.filterWithKey (\k _ -> k `elem` cs) (D.columnIndices left)
leftRowRepresentations = D.computeRowHashes leftIndicesToGroup left
leftKeyCountsAndIndices =
Expand Down