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https://issues.apache.org/jira/browse/ARROW-1753?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16226603#comment-16226603
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ASF GitHub Bot commented on ARROW-1753:
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dhirschfeld commented on a change in pull request #1272: ARROW-1753 [Python]
Provide for matching subclasses with register_type in serialization context
URL: https://github.com/apache/arrow/pull/1272#discussion_r147954573
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File path: python/pyarrow/tests/test_serialization.py
##########
@@ -416,3 +416,22 @@ class TempClass(object):
with pytest.raises(pa.DeserializationCallbackError) as err:
serialized_object.deserialize(deserialization_context)
assert err.value.type_id == 20*b"\x00"
+
+
+def test_match_subclasses():
+ # should be able to serialize/deserialize an instance
+ # if a base class has been registered
+ serialization_context = pa.SerializationContext()
+ context.register_type(Foo, "Foo")
+ context.register_type(Bar, "Bar")
+ context.register_type(Baz, "Baz")
+ context.register_type(Qux, "Quz")
+
+ subqux = SubQux()
+ # should fallbact to Qux serializer
+ serialized_object = pa.serialize(subqux, serialization_context)
+
+ reconstructed_object = serialized_object.deserialize(
+ serialization_context
+ )
+ assert type(reconstructed_object) == Qux
Review comment:
IIUC, without any special handling in
[`_deserialize_callback`](https://github.com/dhirschfeld/arrow/blob/1fc2479cdd60493ebf5a8a4a8c556a63d121257f/python/pyarrow/serialization.pxi#L121)
you'll lose the information about the particular subclass.
I've punted on this for now because I'm not entirely sure how you could do
this robustly in a generic fashion.
In my own code I'm thinking of providing a custom deserializer and storing
the subclass information in the serialized object but I'm not sure this is a
good *general* solution.
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> [Python] Provide for matching subclasses with register_type in serialization
> context
> ------------------------------------------------------------------------------------
>
> Key: ARROW-1753
> URL: https://issues.apache.org/jira/browse/ARROW-1753
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Python
> Reporter: Wes McKinney
> Labels: pull-request-available
> Fix For: 0.8.0
>
>
> Copied from https://github.com/apache/arrow/issues/1269
> To allow factoring out serialization code to a common base class it would be
> useful if register_type matches all subclasses rather than simply an exact
> match on the specific type.
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