fix: import bug template params

superset/datasets/schemas.py

@@ -293,6 +293,7 @@ class ImportV1DatasetSchema(Schema):
     def fix_extra(self, data: dict[str, Any], **kwargs: Any) -> dict[str, Any]:
         """
         Fix for extra initially being exported as a string.
+        And fixed bug when exporting template_params as empty string.
         """
         if isinstance(data.get("extra"), str):
             try:
@@ -301,6 +302,9 @@ def fix_extra(self, data: dict[str, Any], **kwargs: Any) -> dict[str, Any]:
             except ValueError:
                 data["extra"] = None
 
+        if "template_params" in data and data["template_params"] == "":
+            data["template_params"] = None
+
         return data
 
     table_name = fields.String(required=True)