This should work according to the spec. What language and Avro library are you using, and with what version?
Aliases are a bit tricky to use correctly. When deserializing, you may need to indicate the writer’s schema as using oldFieldName1 and oldFieldName2, while the reader schema uses newFieldName1 and newFieldName2. In other words, you may need to provide both the old and new schemas to the deserializer. This is just built in to how aliases work ( https://avro.apache.org/docs/current/spec.html#Aliases). This may be a little abstract and unclear; it’s easier to describe in the context of a particular language. On Sat, Jan 15, 2022 at 8:37 AM Spencer Lu <spencer...@gmail.com> wrote: > Hi everyone, > > We have an application that receives Avro data, and it needs to rename > certain fields in the data before sending it downstream. The > application is using the following Avro schema to send the data > downstream (note that 2 of the fields have aliases defined): > > { > "name":"MyCompanyRecordAvroEncoder", > "aliases":["com.mycompany.avro.MyStats"], > "type":"record", > "fields":[ > {"name":"newFieldName1","type":["null", > "int"],"default":null,"aliases":["oldFieldName1"]} > > {"name":"statusRecords","type":{"type":"array","items":{"name":"StatusAvroRecord","type":"record","fields" > : [ > {"name":"recordId","type":"long"}, > {"name":"recordName","type":["null", "string"],"default":null}, > {"name":"newFieldName2","type":["null", > "string"],"default":null,"aliases":["oldFieldName2"]} > ]}}, "default": []} > ] > } > > We see that our application receives the following Avro data: > > { > "oldFieldName1": 300, > "statusRecords": [ > { > "recordId": 100, > "recordName": "Record1", > "oldFieldName2": > > "{\"type\":\"XYZ\",\"properties\":{\"property1\":-1.2,\"property2\":\"Value\"}}" > } > ] > } > > Then the application sends the following Avro data downstream: > > { > "newFieldName1": 300, > "statusRecords": [ > { > "recordId": 100, > "recordName": "Record1", > "newFieldName2": null > } > ] > } > > As you can see, newFieldName1 is aliased to oldFieldName1 and has the > value from oldFieldName1, so its alias is working. > > However, newFieldName2 is aliased to oldFieldName2, but it is null > instead of having the value from oldFieldName2, so its alias is not > working. > > The only difference I see between newFieldName1 and newFieldName2 is > that newFieldName2 is a field within an array item. Do aliases not > work for fields in array items? Or is there some other issue? > > Any idea how can I get the alias for newFieldName2 to work? > > Thanks, > Spencer >
