fix: improve error messages for DataFrame registration and version handling

Author: kosiew

python/datafusion/__init__.py

@@ -66,7 +66,10 @@
     udwf,
 )
 
-__version__ = importlib_metadata.version(__name__)
+try:
+    __version__ = importlib_metadata.version(__name__)
+except importlib_metadata.PackageNotFoundError:
+    __version__ = "0.0.0"
 
 __all__ = [
     "Accumulator",

python/datafusion/context.py

@@ -750,6 +750,10 @@ def register_table(self, name: str, table: Table | TableProvider) -> None:
         The registered table can be referenced from SQL statements executed against
         this context.
 
+        Plain :py:class:`~datafusion.dataframe.DataFrame` objects are not supported;
+        convert them first with :meth:`datafusion.dataframe.DataFrame.into_view` or
+        :meth:`datafusion.catalog.TableProvider.from_dataframe`.
+
         Args:
             name: Name of the resultant table.
             table: DataFusion :class:`Table` or :class:`TableProvider` to add to the

python/tests/test_context.py

@@ -356,9 +356,14 @@ def test_table_provider_from_capsule_invalid():
 
 def test_register_table_with_dataframe_errors(ctx):
     df = ctx.from_pydict({"a": [1]})
-    with pytest.raises(Exception):  # noqa: B017
+    with pytest.raises(Exception) as exc_info:  # noqa: B017
         ctx.register_table("bad", df)
 
+    assert (
+        str(exc_info.value)
+        == "Expected a Table or TableProvider. Convert DataFrames with \"DataFrame.into_view()\" or \"TableProvider.from_dataframe()\"."
+    )
+
 
 def test_register_dataset(ctx):
     # create a RecordBatch and register it as a pyarrow.dataset.Dataset

src/context.rs

@@ -618,7 +618,7 @@ impl PySessionContext {
             py_provider.into_inner()
         } else {
             return Err(crate::errors::PyDataFusionError::Common(
-                "Expected a Table or TableProvider.".to_string(),
+                "Expected a Table or TableProvider. Convert DataFrames with \"DataFrame.into_view()\" or \"TableProvider.from_dataframe()\".".to_string(),
             ));
         };