fix(dataset): raise a clear error when custom dataset_info is not a list

swift/dataset/register.py

@@ -81,7 +81,7 @@ def _register_d_info(d_info: Dict[str, Any], *, base_dir: Optional[str] = None)
     return dataset_meta
 
 
-def register_dataset_info(dataset_info: Union[str, List[str], None] = None) -> List[DatasetMeta]:
+def register_dataset_info(dataset_info: Union[str, list, None] = None) -> List[DatasetMeta]:
     """Register dataset from the `dataset_info.json` or a custom dataset info file
     This is used to deal with the datasets defined in the json info file.
 
@@ -103,13 +103,18 @@ def register_dataset_info(dataset_info: Union[str, List[str], None] = None) -> L
                 dataset_info = json.load(f)
         else:
             dataset_info = json.loads(dataset_info)  # json
+    if not isinstance(dataset_info, list):
+        raise ValueError(f'`dataset_info` should be a JSON list of dataset entries (e.g. `[{{...}}]`), but got '
+                         f'type `{type(dataset_info).__name__}`. Please wrap the entry in a list.')
     if len(dataset_info) == 0:
         return []
     res = []
     for d_info in dataset_info:
         res.append(_register_d_info(d_info, base_dir=base_dir))
 
     if log_msg is None:
-        log_msg = dataset_info if len(dataset_info) < 5 else list(dataset_info.keys())
+        # dataset_info is a list here; slice it (the old `.keys()` dated to when
+        # it was a dict and now raises AttributeError for 5+ entries).
+        log_msg = dataset_info if len(dataset_info) < 5 else dataset_info[:5]
     logger.info(f'Successfully registered `{log_msg}`.')
     return res

tests/general/test_dataset.py

@@ -79,6 +79,31 @@ def test_cls():
     _test_dataset(['simpleai/HC3-Chinese:baike_cls'])
 
 
+def test_register_dataset_info_rejects_non_list():
+    import json
+    import os
+    import tempfile
+
+    from swift.dataset import register_dataset_info
+
+    # A single entry written as a top-level object instead of a one-element list is a
+    # common mistake; it must fail with a clear message rather than a cryptic
+    # "'str' object does not support item assignment" from iterating the dict keys.
+    with tempfile.NamedTemporaryFile('w', suffix='.json', delete=False, encoding='utf-8') as f:
+        json.dump({'ms_dataset_id': 'swift/self-cognition'}, f)
+        path = f.name
+
+    try:
+        try:
+            register_dataset_info(path)
+        except ValueError as e:
+            assert 'list' in str(e)
+        else:
+            raise AssertionError('expected ValueError for a non-list dataset_info')
+    finally:
+        os.remove(path)
+
+
 if __name__ == '__main__':
     # test_sft()
     # test_agent()