fix: excel in node only read one sheet, close #9661 (#11215)

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

api/core/workflow/nodes/document_extractor/node.py

@@ -4,8 +4,8 @@ import json
 
 import docx
 import pandas as pd
-import pypdfium2
-import yaml
+import pypdfium2  # type: ignore
+import yaml  # type: ignore
 from unstructured.partition.api import partition_via_api
 from unstructured.partition.email import partition_email
 from unstructured.partition.epub import partition_epub
@@ -237,15 +237,17 @@ def _extract_text_from_csv(file_content: bytes) -> str:
 
 def _extract_text_from_excel(file_content: bytes) -> str:
     """Extract text from an Excel file using pandas."""
-
     try:
-        df = pd.read_excel(io.BytesIO(file_content))
-
-        # Drop rows where all elements are NaN
-        df.dropna(how="all", inplace=True)
-
-        # Convert DataFrame to Markdown table
-        markdown_table = df.to_markdown(index=False)
+        excel_file = pd.ExcelFile(io.BytesIO(file_content))
+        markdown_table = ""
+        for sheet_name in excel_file.sheet_names:
+            try:
+                df = excel_file.parse(sheet_name=sheet_name)
+                df.dropna(how="all", inplace=True)
+                # Create Markdown table two times to separate tables with a newline
+                markdown_table += df.to_markdown(index=False) + "\n\n"
+            except Exception as e:
+                continue
         return markdown_table
     except Exception as e:
         raise TextExtractionError(f"Failed to extract text from Excel file: {str(e)}") from e