paleolimbot commented on code in PR #464:
URL: https://github.com/apache/arrow-nanoarrow/pull/464#discussion_r1603395224
##########
python/src/nanoarrow/visitor.py:
##########
@@ -156,18 +274,23 @@ def __init__(self, schema, *, array_view=None):
self._schema.children, self._array_view.children
):
self._child_visitors.append(
- self._resolve_child_visitor(child_schema, child_array_view)
+ self._resolve_child_visitor(
+ child_schema, child_array_view, handle_nulls
+ )
)
- def _resolve_child_visitor(self, child_schema, child_array_view):
- # TODO: Resolve more efficient column builders for single-buffer types
- return ListBuilder(child_schema, array_view=child_array_view)
+ def _resolve_child_visitor(self, child_schema, child_array_view,
handle_nulls):
+ cls, kwargs = _resolve_column_builder_cls(child_schema, handle_nulls)
+ return cls(child_schema, **kwargs, array_view=child_array_view)
def begin(self, total_elements: Union[int, None] = None) -> None:
for child_visitor in self._child_visitors:
child_visitor.begin(total_elements)
def visit_chunk_view(self, array_view: CArrayView) -> Any:
+ if array_view.null_count > 0:
+ raise ValueError("null_count > 0 encountered in ColumnsBuilder")
Review Comment:
If there are any nulls here the column results will be bogus! (We have no
way to propagate a top-level nulls through into the child columns). At the
"record batch" level nulls don't exist (typically they are exported as an
explicitly non-nullable struct; however, at least one implementation doesn't do
this so we have to check for actual nulls whilst iterating instead of erroring
when we see the schema).
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