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https://issues.apache.org/jira/browse/ARROW-10960?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David Li resolved ARROW-10960.
------------------------------
Fix Version/s: 3.0.0
Resolution: Fixed
Issue resolved by pull request 8962
[https://github.com/apache/arrow/pull/8962]
> [C++][FlightRPC] Missing protobuf data_body should result in default value of
> empty bytes, not null
> ---------------------------------------------------------------------------------------------------
>
> Key: ARROW-10960
> URL: https://issues.apache.org/jira/browse/ARROW-10960
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, FlightRPC
> Reporter: Carol Nichols
> Assignee: Carol Nichols
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.0.0
>
> Attachments: cpp-client-empty-data-body.png,
> rust-client-missing-data-body.png
>
> Time Spent: 2h
> Remaining Estimate: 0h
>
> h1. Problem
> ProtoBuf {{proto3}} specifies that [if a message does not contain a
> particular singular element, the field should get the default
> value|https://developers.google.com/protocol-buffers/docs/proto3#default].
> However, when the C++ {{flight-test-integration-server}} gets a {{DoPut}}
> request with a {{FlightData}} message for a record batch containing no items,
> and the {{FlightData}} is missing the {{data_body}} field, the server
> responds with an error "Expected body in IPC message of type record batch".
> h2. What happens
> If I run the C++ {{flight-test-integration-server}} and the C++
> {{flight-test-integration-client}} with the {{generated_null_trivial}} test
> case, the test passes and I see the protobuf in wireshark shown in the
> cpp-client-empty-data-body.png attachment.
> Note the {{data_body}} field is present but has no value.
> If I run the Rust {{flight-test-integration-client}} that I'm working on
> developing, it does not send the {{data_body}} field at all if there are no
> bytes to send. I see the protobuf in wireshark shown in the
> rust-client-missing-data-body.png attachment.
> Note the {{data_body}} field is not present.
> The C++ server then returns the error message "Expected body in IPC message
> of type record batch", which comes from [this check for message
> body|https://github.com/apache/arrow/blob/519e9da4fc1698f686525f4226295f3680a3f3db/cpp/src/arrow/ipc/reader.cc#L92]
> called in [{{ReadNext}} of the record batch stream
> reader|https://github.com/apache/arrow/blob/519e9da4fc1698f686525f4226295f3680a3f3db/cpp/src/arrow/ipc/reader.cc#L787].
> h2. What I expect to happen
> Instead of returning an error message because of a null pointer, the Message
> should get the default value of empty bytes.
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