do not overwrite version with None in DatasetQuery constructor (#92)

src/datachain/query/dataset.py

@@ -1090,16 +1090,14 @@ def __init__(
             self.feature_schema = indexing_feature_schema
             self.column_types = indexing_column_types
         elif name:
+            self.name = name
             ds = self.catalog.get_dataset(name)
             self.version = version or ds.latest_version
             self.feature_schema = ds.get_version(self.version).feature_schema
             self.column_types = copy(ds.schema)
             if "sys__id" in self.column_types:
                 self.column_types.pop("sys__id")
             self.starting_step = QueryStep(self.catalog, name, self.version)
-            # attaching to specific dataset
-            self.name = name
-            self.version = version
         else:
             raise ValueError("must provide path or name")
 

tests/unit/lib/test_datachain.py

@@ -522,6 +522,23 @@ def test_select_restore_from_saving(catalog):
     assert n == len(features_nested)
 
 
+def test_from_dataset_name_version(catalog):
+    name = "test-version"
+    DataChain.from_values(
+        first_name=["Alice", "Bob", "Charlie"],
+        age=[40, 30, None],
+        city=[
+            "Houston",
+            "Los Angeles",
+            None,
+        ],
+    ).save(name)
+
+    dc = DataChain.from_dataset(name)
+    assert dc.name == name
+    assert dc.version
+
+
 def test_chain_of_maps(catalog):
     dc = (
         DataChain.from_values(my_n=features_nested)