fix(dc): collect function return types (#589)

src/datachain/lib/dc.py

@@ -30,7 +30,7 @@
 from datachain.dataset import DatasetRecord
 from datachain.lib.convert.python_to_sql import python_to_sql
 from datachain.lib.convert.values_to_tuples import values_to_tuples
-from datachain.lib.data_model import DataModel, DataType, dict_to_data_model
+from datachain.lib.data_model import DataModel, DataType, DataValue, dict_to_data_model
 from datachain.lib.dataset_info import DatasetInfo
 from datachain.lib.file import ArrowRow, File, get_file_type
 from datachain.lib.file import ExportPlacement as FileExportPlacement
@@ -1262,15 +1262,15 @@ def to_dict(cols: list[str], row: tuple[Any, ...]) -> dict[str, Any]:
         return self.results(row_factory=to_dict)
 
     @overload
-    def collect(self) -> Iterator[tuple[DataType, ...]]: ...
+    def collect(self) -> Iterator[tuple[DataValue, ...]]: ...
 
     @overload
-    def collect(self, col: str) -> Iterator[DataType]: ...  # type: ignore[overload-overlap]
+    def collect(self, col: str) -> Iterator[DataValue]: ...
 
     @overload
-    def collect(self, *cols: str) -> Iterator[tuple[DataType, ...]]: ...
+    def collect(self, *cols: str) -> Iterator[tuple[DataValue, ...]]: ...
 
-    def collect(self, *cols: str) -> Iterator[Union[DataType, tuple[DataType, ...]]]:  # type: ignore[overload-overlap,misc]
+    def collect(self, *cols: str) -> Iterator[Union[DataValue, tuple[DataValue, ...]]]:  # type: ignore[overload-overlap,misc]
         """Yields rows of values, optionally limited to the specified columns.
 
         Args:

src/datachain/lib/meta_formats.py

@@ -114,6 +114,7 @@ def read_meta(  # noqa: C901
             )
         )
         (model_output,) = chain.collect("meta_schema")
+        assert isinstance(model_output, str)
         if print_schema:
             print(f"{model_output}")
         # Below 'spec' should be a dynamically converted DataModel from Pydantic

src/datachain/lib/signal_schema.py

@@ -378,7 +378,7 @@ def slice(
 
     def row_to_features(
         self, row: Sequence, catalog: "Catalog", cache: bool = False
-    ) -> list[DataType]:
+    ) -> list[DataValue]:
         res = []
         pos = 0
         for fr_cls in self.values.values():