get append by iterable working

python/src/nanoarrow/_schema.pyx

@@ -555,6 +555,8 @@ cdef class CSchemaView:
             (_types.TIMESTAMP, _types.DATE64, _types.DURATION)
         ):
             return 'q'
+        elif self.extension_name:
+            return self._get_buffer_format()
         else:
             return None
 
@@ -564,7 +566,13 @@ cdef class CSchemaView:
         or None if there is no Python format string that can represent this
         type without loosing information.
         """
-        if self.extension_name or self._schema_view.type != self._schema_view.storage_type:
+        if self.extension_name:
+            return None
+        else:
+            return self._get_buffer_format()
+
+    def _get_buffer_format(self):
+        if self._schema_view.type != self._schema_view.storage_type:
             return None
 
         # String/binary types do not have format strings as far as the Python

python/src/nanoarrow/c_array.py

@@ -24,6 +24,7 @@
 from nanoarrow._utils import obj_is_buffer, obj_is_capsule
 from nanoarrow.c_buffer import c_buffer
 from nanoarrow.c_schema import c_schema, c_schema_view
+from nanoarrow.extension import resolve_extension
 
 from nanoarrow import _types
 
@@ -462,6 +463,13 @@ def __init__(self, schema):
 
         # Resolve the method name we are going to use to do the building from
         # the provided schema.
+        ext = resolve_extension(self._schema_view)
+        if ext is not None:
+            maybe_appender = ext.get_iterable_appender(self._schema, self)
+            if maybe_appender:
+                self._append_impl = maybe_appender
+                return
+
         type_id = self._schema_view.type_id
         if type_id not in _ARRAY_BUILDER_FROM_ITERABLE_METHOD:
             raise ValueError(

python/src/nanoarrow/extension.py

@@ -15,9 +15,10 @@
 # specific language governing permissions and limitations
 # under the License.
 
-from typing import Any, Iterator, Mapping, Optional, Type
+from typing import Any, Iterator, Mapping, Optional, Type, Callable, Iterable
 
 from nanoarrow.c_schema import CSchema, CSchemaView, c_schema_view
+from nanoarrow.c_array import CArrayBuilder
 
 
 class Extension:
@@ -38,6 +39,11 @@ def get_pyiter(
     def get_sequence_converter(self, c_schema: CSchema):
         return None
 
+    def get_iterable_appender(
+        self, c_schema: CSchema, array_builder
+    ) -> Optional[Callable[[Iterable], None]]:
+        return None
+
 
 _global_extension_registry = {}
 
@@ -59,7 +65,9 @@ def register_extension(extension: Extension) -> Optional[Extension]:
     else:
         key = schema_view.type_id
 
-    prev = _global_extension_registry[key] if key in _global_extension_registry else None
+    prev = (
+        _global_extension_registry[key] if key in _global_extension_registry else None
+    )
     _global_extension_registry[key] = extension
     return prev
 

python/src/nanoarrow/extension_canonical.py

@@ -17,6 +17,7 @@
 
 from typing import Any, Iterator, Mapping, Optional
 
+from nanoarrow.c_array import CArrayBuilder
 from nanoarrow.c_buffer import CBufferBuilder
 from nanoarrow.c_schema import CSchema, c_schema_view
 from nanoarrow.schema import extension_type, int8
@@ -33,7 +34,7 @@ def bool8(nullable: bool = True):
         Use ``False`` to mark this field as non-nullable.
     """
 
-    return extension_type(int8(nullable=nullable), "arrow.bool8")
+    return extension_type(int8(), "arrow.bool8", nullable=nullable)
 
 
 class Bool8SequenceConverter(ToPyBufferConverter):
@@ -72,3 +73,7 @@ def get_pyiter(
     def get_sequence_converter(self, c_schema: CSchema):
         self.get_params(c_schema)
         return Bool8SequenceConverter
+
+    def get_sequence_appender(self, c_schema: CSchema, array_builder):
+        self.get_params(c_schema)
+        return None

python/tests/test_canonical_extension.py

@@ -25,19 +25,19 @@ def test_extension_bool8():
     assert schema.extension.name == "arrow.bool8"
     assert schema.extension.metadata == b""
 
-    buf = na.c_buffer([1, 0, 1, 1], na.int8())
-    bool8_array = na.Array(na.c_array_from_buffers(schema, 4, [None, buf]))
+    assert na.bool8(nullable=False).nullable is False
+
+    bool8_array = na.Array([True, False, True, True], na.bool8())
     assert bool8_array.schema.type == na.Type.EXTENSION
     assert bool8_array.schema.extension.name == "arrow.bool8"
     assert bool8_array.to_pylist() == [True, False, True, True]
 
     sequence = bool8_array.to_pysequence()
     assert list(sequence) == [True, False, True, True]
 
-    validity = na.c_buffer([True, True, False, True], na.bool_())
-    bool8_array = na.Array(na.c_array_from_buffers(schema, 4, [validity, buf]))
+    bool8_array = na.Array([True, False, None, True], na.bool8())
     assert bool8_array.to_pylist() == [True, False, None, True]
 
     sequence = bool8_array.to_pysequence(handle_nulls=na.nulls_separate())
-    assert list(sequence[1]) == [True, False, True, True]
+    assert list(sequence[1]) == [True, False, False, True]
     assert list(sequence[0]) == [True, True, False, True]