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https://issues.apache.org/jira/browse/BEAM-8085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ismaël Mejía updated BEAM-8085:
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Status: Open (was: Triage Needed)
> PubsubMessageWithAttributesCoder should not produce null attributes map
> -----------------------------------------------------------------------
>
> Key: BEAM-8085
> URL: https://issues.apache.org/jira/browse/BEAM-8085
> Project: Beam
> Issue Type: Improvement
> Components: io-java-gcp
> Reporter: Chad Dombrova
> Priority: Major
>
> Hi, I just got caught by an issue where PubsubMessage.getAttributeMap()
> returned null, because the message was created by
> PubsubMessageWithAttributesCoder which uses a NullableCoder for attributes.
> Here are the relevant code snippets:
> {code:java}
> public class PubsubMessageWithAttributesCoder extends
> CustomCoder<PubsubMessage> {
> // A message's payload can not be null
> private static final Coder<byte[]> PAYLOAD_CODER = ByteArrayCoder.of();
> // A message's attributes can be null.
> private static final Coder<Map<String, String>> ATTRIBUTES_CODER =
> NullableCoder.of(MapCoder.of(StringUtf8Coder.of(),
> StringUtf8Coder.of()));
> @Override
> public PubsubMessage decode(InputStream inStream) throws IOException {
> return decode(inStream, Context.NESTED);
> }
> @Override
> public PubsubMessage decode(InputStream inStream, Context context) throws
> IOException {
> byte[] payload = PAYLOAD_CODER.decode(inStream);
> Map<String, String> attributes = ATTRIBUTES_CODER.decode(inStream,
> context);
> return new PubsubMessage(payload, attributes);
> }
> }
> {code}
>
> {code:java}
> public class PubsubMessage {
> private byte[] message;
> private Map<String, String> attributes;
> public PubsubMessage(byte[] payload, Map<String, String> attributes) {
> this.message = payload;
> this.attributes = attributes;
> }
> /** Returns the main PubSub message. */
> public byte[] getPayload() {
> return message;
> }
> /** Returns the given attribute value. If not such attribute exists,
> returns null. */
> @Nullable
> public String getAttribute(String attribute) {
> checkNotNull(attribute, "attribute");
> return attributes.get(attribute);
> }
> /** Returns the full map of attributes. This is an unmodifiable map. */
> public Map<String, String> getAttributeMap() {
> return attributes;
> }
> }
> {code}
> There are a handful of potential solutions:
> # Remove the NullableCoder
> # In PubsubMessageWithAttributesCoder.decode, check for null and create an
> empty Map before instantiating PubsubMessage
> # Allow attributes to be null for PubsubMessage constructor, but create an
> empty Map if it is (similar to above, but handle it in PubsubMessage)
> # Allow PubsubMessage.attributes to be nullable, and indicate it as such
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