feat: support xlsx file parsing (#304)

Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

api/core/index/readers/xlsx_parser.py

@@ -0,0 +1,31 @@
+from pathlib import Path
+import json
+from typing import Dict
+from openpyxl import load_workbook
+
+from llama_index.readers.file.base_parser import BaseParser
+from flask import current_app
+
+
+class XLSXParser(BaseParser):
+    """XLSX parser."""
+
+    def _init_parser(self) -> Dict:
+        """Init parser"""
+        return {}
+
+    def parse_file(self, file: Path, errors: str = "ignore") -> str:
+        data = []
+        keys = []
+        with open(file, "r") as fp:
+            wb = load_workbook(filename=file, 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 = row
+                    else:
+                        data.append(json.dumps(dict(zip(keys, row)), ensure_ascii=False))
+        return data