[GitHub] [arrow] lidavidm commented on a change in pull request #8962: ARROW-10960: [C++] [Flight] Default to empty buffer instead of null

[GitBox <gi...@apache.org>]

lidavidm commented on a change in pull request #8962:
URL: https://github.com/apache/arrow/pull/8962#discussion_r546065801



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File path: cpp/src/arrow/flight/serialization_internal.cc
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@@ -374,7 +374,18 @@ grpc::Status FlightDataDeserialize(ByteBuffer* buffer, FlightData* out) {
   buffer->Clear();
 
   // TODO(wesm): Where and when should we verify that the FlightData is not
-  // malformed or missing components?
+  // malformed?
+
+  // Set default values for unspecified FlightData fields
+  if (out->app_metadata == nullptr) {
+    out->app_metadata = std::make_shared<Buffer>(nullptr, 0);
+  }
+  if (out->metadata == nullptr) {
+    out->metadata = std::make_shared<Buffer>(nullptr, 0);
+  }

Review comment:
       I think the test failures might come from this, actually - if there's a metadata buffer, that causes some code to assume this must be a schema or record batch and try to parse it accordingly (but it'll then encounter the empty buffer and fail to parse it).
   
   Also, the app_metadata buffer can be omitted - it's meant to be optional so having an empty vs null one is no big deal.




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