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https://issues.apache.org/jira/browse/AVRO-1870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15382256#comment-15382256
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Sean Busbey commented on AVRO-1870:
-----------------------------------
Since the TrafficLights object being serialized is from the Specific API, it
should be serialized using the SpecificDatumWriter, as Matt suggests. I don't
think we generally guarantee that Specific objects will be serializable with
GenericDatumWriter, though I think it is confusing that we generate classes
that can't be.
Is the AvroMsgManager's serialization method supposed to work with both
generated Specific API classes and Object instances returned from the Generic
API?
> Avro compiler generate JAVA enum interfaces but writeEnum expects
> GenericEnumSymbol
> -----------------------------------------------------------------------------------
>
> Key: AVRO-1870
> URL: https://issues.apache.org/jira/browse/AVRO-1870
> Project: Avro
> Issue Type: Bug
> Components: java
> Affects Versions: 1.8.1
> Reporter: Ali Hashemi
>
> Avro compiler generate an enum JAVA class from an enum Avro type
> and this class is used in the Java class of the records pointing to the enum
> type. However, org.apache.avro.generic.GenericDatumWriter.writeEnum expects a
> GenericEnumSymbol rather than Java Enum!
> This is problem because the class interfaces for Avro messages expect Java
> Enum and not GenericEnumSymbol!
> Consider the following schema:
> TrafficLights.avsc:
> {"namespace": "com.comp.message",
> "type": "record",
> "name": "TrafficLights",
> "fields": [
> {"name": "id", "type": "string"},
> {"name": "signal", "type": "Signals" }
> ]
> }
> Signals.avsc:
> {
> "namespace": "com.comp.message",
> "type": "enum",
> "name":"Signals",
> "symbols" : ["GREEN", "YELLOW", "RED"]
> }
> Using maven-avro-plugin to import "Signals" as an external schema, Avro
> compiler creates the following constructor for TrafficLights class:
> public TrafficLights(java.lang.CharSequence id, com.comp.message.Signals
> signal){...}
> and an Enum class fot the Signals:
> package com.comp.message;
> @SuppressWarnings("all")
> @org.apache.avro.specific.AvroGenerated
> public enum Signals {
> GREEN, YELLOW, RED ;
> public static final org.apache.avro.Schema SCHEMA$ = new
> org.apache.avro.Schema.Parser().parse("{\"type\":\"enum\",\"name\":\"Signals\",\"namespace\":\"com.comp.message\",\"symbols\":[\"GREEN\",\"YELLOW\",\"RED\"]}");
> public static org.apache.avro.Schema getClassSchema() { return SCHEMA$; }
> }
> However, when I try to serialize a TrafficLights message,
> GenericDatumWriter.writeEnum throws an exeception:
> TrafficLights mainTrafficLight = new TrafficLights ("123", Signals.GREEN);
> byte[] msg = new AvroMsgManager( mainTrafficLight .getSchema().toString()
> ).serialize (mainTrafficLight))
> org.apache.avro.AvroTypeException: Not an enum: GREEN
> at
> org.apache.avro.generic.GenericDatumWriter.writeEnum(GenericDatumWriter.java:164)
> at
> org.apache.avro.generic.GenericDatumWriter.writeWithoutConversion(GenericDatumWriter.java:106)
> at
> org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:73)
> at
> org.apache.avro.generic.GenericDatumWriter.writeField(GenericDatumWriter.java:153)
> at
> org.apache.avro.generic.GenericDatumWriter.writeRecord(GenericDatumWriter.java:143)
> at
> org.apache.avro.generic.GenericDatumWriter.writeWithoutConversion(GenericDatumWriter.java:105)
> at
> org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:73)
> at
> org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:60)
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