[jira] [Resolved] (AVRO-1915) AvroTypeException decoding from earlier schema version

["Ryan Blue (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AVRO-1915?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ryan Blue resolved AVRO-1915.
-----------------------------
    Resolution: Not A Problem

Thanks for letting us know you got past this. I'm going to resolve this issue.

> AvroTypeException decoding from earlier schema version
> ------------------------------------------------------
>
>                 Key: AVRO-1915
>                 URL: https://issues.apache.org/jira/browse/AVRO-1915
>             Project: Avro
>          Issue Type: Bug
>          Components: java
>    Affects Versions: 1.7.7
>            Reporter: NPE
>
> We have two services which communicate with one another by sending JSON-encoded Avro-based messages over Kafka.  We want to update the schema for messages sent from service A to service B by adding an additional string field with a default value of "" (empty string).  We have tested by initially adding the updated schema to service B (the reader) and continuing to send messages in the older format from service A (the writer).
> Simplified example of old schema (some fields omitted):
> {code}
> {
> 	"type": "record",
> 	"name": "Envelope",
> 	"fields": [{
> 		"name": "appId",
> 		"type": "string"
> 	}, {
> 		"name": "time",
> 		"type": "long"
> 	}, {
> 		"name": "type",
> 		"type": "string"
> 	}, {
> 		"name": "payload",
> 		"type": [{
> 			"type": "record",
> 			"name": "MessagePayload",
> 			"fields": [{
> 				"name": "context",
> 				"type": {
> 					"type": "record",
> 					"name": "PayloadContext",
> 					"fields": [{
> 						"name": "source",
> 						"type": "string"
> 					}, {
> 						"name": "requestId",
> 						"type": "string"
> 					}]
> 				}
> 			}, {
> 				"name": "content",
> 				"type": "string"
> 			}, {
> 				"name": "contentType",
> 				"type": "string"
> 			}]
> 		}]
> 	}]
> }
> {code}
> Simplified example of new schema (some fields omitted):
> {code}
> {
> 	"type": "record",
> 	"name": "Envelope",
> 	"fields": [{
> 		"name": "appId",
> 		"type": "string"
> 	}, {
> 		"name": "time",
> 		"type": "long"
> 	}, {
> 		"name": "type",
> 		"type": "string"
> 	}, {
> 		"name": "payload",
> 		"type": [{
> 			"type": "record",
> 			"name": "MessagePayload",
> 			"fields": [{
> 				"name": "context",
> 				"type": {
> 					"type": "record",
> 					"name": "PayloadContext",
> 					"fields": [{
> 						"name": "source",
> 						"type": "string"
> 					}, {
> 						"name": "requestId",
> 						"type": "string"
> 					}, {
> 						"name": "newField",
> 						"type": "string",
> 						"default": ""
> 					}]
> 				}
> 			}, {
> 				"name": "content",
> 				"type": "string"
> 			}, {
> 				"name": "contentType",
> 				"type": "string"
> 			}]
> 		}]
> 	}]
> }
> {code}
> Our understanding was that the reader, with the newer schema, should be able to parse messages sent with the older given the default value for the missing field; however, we are getting the following exception:
> {code}
> org.apache.avro.AvroTypeException: Expected string. Got END_OBJECT
> {code}
> Are we missing something here?



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