date and time arrays implement __arrow_array__

to facilitate arrow conversion

google/cloud/bigquery/_pandas_helpers.py

@@ -25,7 +25,7 @@
     import pandas
 except ImportError:  # pragma: NO COVER
     pandas = None
-    date_dtype_name = time_dtype_name = ''  # Use '' rather than None because pytype
+    date_dtype_name = time_dtype_name = ""  # Use '' rather than None because pytype
 else:
     import numpy
 
@@ -310,7 +310,7 @@ def bq_to_arrow_array(series, bq_field):
         return pyarrow.ListArray.from_pandas(series, type=arrow_type)
     if field_type_upper in schema._STRUCT_TYPES:
         return pyarrow.StructArray.from_pandas(series, type=arrow_type)
-    return pyarrow.Array.from_pandas(series.to_numpy(), type=arrow_type)
+    return pyarrow.Array.from_pandas(series, type=arrow_type)
 
 
 def get_column_or_index(dataframe, name):

google/cloud/bigquery/dtypes.py

@@ -30,6 +30,7 @@
 import pandas.core.dtypes.dtypes
 import pandas.core.dtypes.generic
 import pandas.core.nanops
+import pyarrow
 
 pandas_release = packaging.version.parse(pandas.__version__).release
 
@@ -381,6 +382,11 @@ def astype(self, dtype, copy=True):
         else:
             return super().astype(dtype, copy=copy)
 
+    def __arrow_array__(self, type=None):
+        return pyarrow.array(
+            self.to_numpy(), type=type if type is not None else pyarrow.time64("ns"),
+        )
+
 
 @pandas.core.dtypes.dtypes.register_extension_dtype
 class DateDtype(_BaseDtype):
@@ -435,3 +441,8 @@ def astype(self, dtype, copy=True):
             return self._ndarray.astype(dtype, copy=copy)
 
         return super().astype(dtype, copy=copy)
+
+    def __arrow_array__(self, type=None):
+        return pyarrow.array(
+            self._ndarray, type=type if type is not None else pyarrow.date32(),
+        )