cherry-pick ef659a1e

lightrag/api/routers/document_routes.py

@@ -1063,7 +1063,7 @@ def _extract_xlsx(file_bytes: bytes) -> str:
     - Special characters (tabs, newlines, backslashes) are escaped to prevent structure corruption
     - Column alignment is preserved across all rows to maintain tabular structure
     - Empty rows are preserved as blank lines to maintain row structure
-    - Uses sheet.max_column to determine column width efficiently
+    - Two-pass processing: determines max column width, then extracts with consistent alignment
 
     Args:
         file_bytes: XLSX file content as bytes
@@ -1133,11 +1133,23 @@ def _extract_xlsx(file_bytes: bytes) -> str:
         safe_title = escape_sheet_title(sheet.title)
         content_parts.append(f"{sheet_separator} Sheet: {safe_title} {sheet_separator}")
 
-        # Use sheet.max_column to get the maximum column width directly
-        max_columns = sheet.max_column if sheet.max_column else 0
+        # Two-pass approach to preserve column alignment:
+        # Pass 1: Determine the maximum column width for this sheet
+        max_columns = 0
+        all_rows = list(sheet.iter_rows(values_only=True))
 
-        # Extract rows with consistent width to preserve column alignment
-        for row in sheet.iter_rows(values_only=True):
+        for row in all_rows:
+            last_nonempty_idx = -1
+            for idx, cell in enumerate(row):
+                # Check if cell has meaningful content (not None or empty string)
+                if cell is not None and str(cell).strip():
+                    last_nonempty_idx = idx
+
+            if last_nonempty_idx >= 0:
+                max_columns = max(max_columns, last_nonempty_idx + 1)
+
+        # Pass 2: Extract rows with consistent width to preserve column alignment
+        for row in all_rows:
             row_parts = []
 
             # Build row up to max_columns width