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https://issues.apache.org/jira/browse/AVRO-1870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15392097#comment-15392097
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Sean Busbey commented on AVRO-1870:
-----------------------------------
I think historically Specific API objects happened to work with the
GenericDatumWriter, even though we don't claim that they will. If you're going
to process both Specific and Generic API objects, you should use
SpecificDatumWriter. All the better if you can differentiate between Generic
and Specific and use the appropriate writer with each.
> 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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