feat: upgrade langchain (#430)

Co-authored-by: jyong <718720800@qq.com>

api/core/data_loader/loader/excel.py

@@ -0,0 +1,43 @@
+import json
+import logging
+from typing import List
+
+from langchain.document_loaders.base import BaseLoader
+from langchain.schema import Document
+from openpyxl.reader.excel import load_workbook
+
+logger = logging.getLogger(__name__)
+
+
+class ExcelLoader(BaseLoader):
+    """Load xlxs files.
+
+
+    Args:
+        file_path: Path to the file to load.
+    """
+
+    def __init__(
+        self,
+        file_path: str
+    ):
+        """Initialize with file path."""
+        self._file_path = file_path
+
+    def load(self) -> List[Document]:
+        data = []
+        keys = []
+        wb = load_workbook(filename=self._file_path, read_only=True)
+        # loop over all sheets
+        for sheet in wb:
+            for row in sheet.iter_rows(values_only=True):
+                if all(v is None for v in row):
+                    continue
+                if keys == []:
+                    keys = list(map(str, row))
+                else:
+                    row_dict = dict(zip(keys, row))
+                    row_dict = {k: v for k, v in row_dict.items() if v}
+                    data.append(json.dumps(row_dict, ensure_ascii=False))
+
+        return [Document(page_content='\n\n'.join(data))]