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https://issues.apache.org/jira/browse/AVRO-2184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16513741#comment-16513741
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ASF GitHub Bot commented on AVRO-2184:
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nandorKollar opened a new pull request #316: AVRO-2184: Unable to decode JSON
data file if a property is renamed in reader schema
URL: https://github.com/apache/avro/pull/316
JsonDecoder doesn't honor aliases
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> Unable to decode JSON data file if a property is renamed in reader schema
> -------------------------------------------------------------------------
>
> Key: AVRO-2184
> URL: https://issues.apache.org/jira/browse/AVRO-2184
> Project: Avro
> Issue Type: Bug
> Reporter: Prateek Kohli
> Priority: Major
> Attachments: TestAliasesInSchemaEvolution.java
>
>
> I am unable to decode JSON data file if a property is renamed in reader
> schema:
> As per the documentation it is a compatible change.
> Also, Datatype promotion is not being supported, if I try to change the
> datatype of favourite_number field in the writer's schema, decoding fails.
> All of the above scenarios are supported if I use Binary decoding instead of
> JSON.
> *Writer Schema :*
> {"namespace": "example.avro",
> "type": "record",
> "name": "User",
> "fields": [
> \{"name": "name", "type": "string"},
> \{"name": "favorite_number", "type": ["int", "null"]},
> \{"name": "favorite_color", "type": ["string", "null"]}
> ]}
>
> *Reader Schema :*
> {"namespace": "example.avro",
> "type": "record",
> "name": "User",
> "fields": [
> \{"name": "fname", "type": "string", "aliases" : [ "name" ]},
> \{"name": "favorite_number", "type": ["int", "null"]},
> \{"name": "favorite_color", "type": ["string", "null"]}
> ]}
>
> *I have written the below code to decode JSON data:*
> FileInputStream fin = new FileInputStream(file);
> byte fileContent[] = new byte[(int)file.length()];
> fin.read(fileContent);
> InputStream input = new ByteArrayInputStream(fileContent);
> DataInputStream din = new DataInputStream(input);
>
> while (true) {
> try {
> Decoder decoder = DecoderFactory.get().jsonDecoder(schema, din);
> ResolvingDecoder resolvingDecoder =
> DecoderFactory.get().resolvingDecoder(writer,
> reader, decoder);
> Object datum = datumReader.read(null, resolvingDecoder);
> System.out.println(datum);
> } catch (EOFException eofException) {
> break;
> }
> }
> *Below is the Exception I get :*
> Exception in thread "main" org.apache.avro.AvroTypeException: Found
> example.avro.User, expecting example.avro.User, missing required field fname
> at org.apache.avro.io.ResolvingDecoder.doAction(ResolvingDecoder.java:292)
> at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
> at org.apache.avro.io.ResolvingDecoder.readString(ResolvingDecoder.java:196)
> at org.apache.avro.io.ResolvingDecoder.readString(ResolvingDecoder.java:201)
> at
> org.apache.avro.generic.GenericDatumReader.readString(GenericDatumReader.java:422)
> at
> org.apache.avro.generic.GenericDatumReader.readString(GenericDatumReader.java:414)
> at
> org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:181)
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:153)
> at
> org.apache.avro.generic.GenericDatumReader.readField(GenericDatumReader.java:232)
> at
> org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:222)
> at
> org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:175)
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:153)
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:145)
> at
> com.ericsson.avroTest.avroCheck.WithoutCodeTest.main(WithoutCodeTest.java:134)
>
>
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