fix(datasource): handle CSV extensions case-insensitively

backend/apps/datasource/api/datasource.py

@@ -33,7 +33,7 @@
 from ..crud.table import get_tables_by_ds_id
 from ..models.datasource import CoreDatasource, CreateDatasource, TableObj, CoreTable, CoreField, FieldObj, \
     TableSchemaResponse, ColumnSchemaResponse, PreviewResponse, ImportRequest
-from ..utils.excel import parse_excel_preview, read_import_dataframe
+from ..utils.excel import is_csv_file, parse_excel_preview, read_import_dataframe
 
 router = APIRouter(tags=["Datasource"], prefix="/datasource")
 path = settings.EXCEL_PATH
@@ -363,7 +363,7 @@ async def upload_excel(trans: Trans, session: SessionDep,
     def inner():
         sheets = []
         engine = get_engine_conn()
-        if filename.endswith(".csv"):
+        if is_csv_file(filename):
             df = pd.read_csv(save_path, engine='c')
             tableName = f"sheet1_{hashlib.sha256(uuid.uuid4().bytes).hexdigest()[:10]}"
             sheets.append({"tableName": tableName, "tableComment": ""})
@@ -633,7 +633,7 @@ def inner():
             field_mapping = {f.fieldName: f.fieldType for f in fields}
             try:
                 df = read_import_dataframe(save_path, sheet_name, field_mapping)
-                if save_path.endswith(".csv"):
+                if is_csv_file(save_path):
                     sheet_name = "Sheet1"
             except Exception as e:
                 raise HTTPException(500, f"{trans('i18n_ds_upload_error')}: {str(e)}")

backend/apps/datasource/utils/excel.py

@@ -22,6 +22,10 @@
 }
 
 
+def is_csv_file(file_path: str) -> bool:
+    return file_path.lower().endswith(".csv")
+
+
 def infer_field_type(dtype) -> str:
     dtype_str = str(dtype)
     return FIELD_TYPE_MAP.get(dtype_str, 'string')
@@ -51,7 +55,7 @@ def read_import_dataframe(save_path: str, sheet_name: str, field_mapping: dict):
         column: 'object' if field_type == 'int' else USER_TYPE_TO_PANDAS.get(field_type, 'string')
         for column, field_type in field_mapping.items()
     }
-    if save_path.endswith('.csv'):
+    if is_csv_file(save_path):
         df = pd.read_csv(save_path, engine='c', dtype=dtype_dict)
     else:
         df = pd.read_excel(save_path, sheet_name=sheet_name, engine='calamine', dtype=dtype_dict)
@@ -68,7 +72,7 @@ def read_import_dataframe(save_path: str, sheet_name: str, field_mapping: dict):
 
 def parse_excel_preview(save_path: str, max_rows: int = 10):
     sheets_data = []
-    if save_path.endswith(".csv"):
+    if is_csv_file(save_path):
         df = pd.read_csv(save_path, engine='c')
         fields = []
         for col in df.columns:

backend/tests/test_datasource_csv_extension.py

@@ -0,0 +1,39 @@
+import pandas as pd
+import pytest
+
+from apps.datasource.utils.excel import parse_excel_preview, read_import_dataframe
+
+
+@pytest.fixture(params=["csv", "CSV", "CsV"])
+def stored_csv(tmp_path, request):
+    path = tmp_path / f"sales_0123456789.{request.param}"
+    path.write_text("region,units\nEast,3\nWest,7\n", encoding="utf-8")
+    return str(path)
+
+
+def test_preview_csv_with_any_extension_case(stored_csv):
+    [sheet] = parse_excel_preview(stored_csv)
+    assert sheet["sheetName"] == "Sheet1"
+    assert sheet["rows"] == 2
+    assert sheet["data"] == [
+        {"region": "East", "units": 3},
+        {"region": "West", "units": 7},
+    ]
+
+
+def test_import_stored_csv_with_any_extension_case(stored_csv):
+    frame = read_import_dataframe(
+        stored_csv, "Sheet1", {"region": "string", "units": "int"}
+    )
+    assert frame["region"].tolist() == ["East", "West"]
+    assert frame["units"].tolist() == [3, 7]
+
+
+def test_excel_reader_preserves_named_sheet(tmp_path):
+    path = tmp_path / "sales.CSV.xlsx"
+    pd.DataFrame({"units": [3]}).to_excel(path, sheet_name="Sales", index=False)
+
+    [sheet] = parse_excel_preview(str(path))
+    assert sheet["sheetName"] == "Sales"
+    frame = read_import_dataframe(str(path), "Sales", {"units": "int"})
+    assert frame["units"].tolist() == [3]

backend/tests/test_datasource_upload_path_traversal.py

@@ -122,3 +122,15 @@ def test_normal_names_keep_their_own_stem_and_extension(parse_harness):
     stored = response.json()["filePath"]
     assert stored.startswith("a.b_") and stored.endswith(".xlsx"), stored
     assert (parse_harness.upload_dir / stored).is_file()
+
+
+def test_legacy_upload_imports_mixed_case_csv(harness, monkeypatch):
+    insert = Mock()
+    monkeypatch.setattr(datasource, "insert_pg", insert)
+    response = harness.client.post(
+        UPLOAD_URL, files={"file": ("orders.CsV", b"units\n3\n7\n", "text/csv")}
+    )
+    assert response.status_code == 200, response.text
+    insert.assert_called_once()
+    frame = insert.call_args.args[0]
+    assert frame.to_dict("records") == [{"units": 3}, {"units": 7}]