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https://issues.apache.org/jira/browse/AVRO-3182?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17398119#comment-17398119
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Ryan Skraba edited comment on AVRO-3182 at 8/12/21, 3:05 PM:
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Hello! It looks like this would be a change to the
[specification|https://avro.apache.org/docs/1.10.2/spec.html#schemas] – it
currently says that the form \{ "type" : "typeName" } should have a string name.
As a consequence, for example, we currently can't set properties on a UNION.
That's always seemed a bit odd to me, but it's never actually been a problem in
practice.
I checked the python SDK and it has the same behaviour as the Java SDK:
{code:java}
avro.schema.parse('{"type": ["null", "string"]}') {code}
raises:
{code:java}
avro.schema.SchemaParseException: Undefined type: ['null', 'string'] {code}
Do you think it would be better to fix this as a bug in the C# SDK?
was (Author: ryanskraba):
Hello! It looks like this would be a change to the
[specification|https://avro.apache.org/docs/1.10.2/spec.html#schemas] – it
currently says that the form {{{ "type" : "typeName" } }}should have a name.
As a consequence, for example, we currently can't set properties on a UNION.
That's always seemed a bit odd to me, but it's never actually been a problem in
practice.
I checked the python SDK and it has the same behaviour as the Java SDK:
{code:java}
avro.schema.parse('{"type": ["null", "string"]}') {code}
raises:
{code:java}
avro.schema.SchemaParseException: Undefined type: ['null', 'string'] {code}
Do you think it would be better to fix this as a bug in the C# SDK?
> Avro in Java cannot parse the union schema from C#
> --------------------------------------------------
>
> Key: AVRO-3182
> URL: https://issues.apache.org/jira/browse/AVRO-3182
> Project: Apache Avro
> Issue Type: Bug
> Components: csharp, java
> Affects Versions: 1.10.2
> Reporter: Shawn Wu
> Priority: Critical
>
> Version: 1.10.2
>
> I need to transfer data from C# to Java.
> When I use Avro in C#, I found [Schema.ToString() in
> C#|https://github.com/apache/avro/blob/master/lang/csharp/src/apache/main/Schema/Schema.cs#L272]
> for union schema will add an extra *type* property in JSON string.
> However, the correct union schema is a JSON array.
> This is my test code in C#:
> {code:java}
> var columnCountSchema =
> Schema.Parse("{\"type\":\"record\",\"name\":\"columnCount\",\"namespace\":\"avro.test.header\",\"fields\":[{\"name\":\"columnCount\",\"type\":\"int\"}]}");
> var errorMessageSchema =
> Schema.Parse("{\"type\":\"record\",\"name\":\"errorMessage\",\"namespace\":\"avro.test.header\",\"fields\":[{\"name\":\"errorMessage\",\"type\":[\"string\",\"null\"]}]}");
> var schema = Schema.Parse($"[{columnCountSchema},{errorMessageSchema}]");
> Console.WriteLine(schema.ToString());{code}
> The output:
> {code:java}
> {"type":[{"type":"record","name":"columnCount","namespace":"avro.test.header","fields":[{"name":"columnCount","type":"int"}]},{"type":"record","name":"errorMessage","namespace":"avro.test.header","fields":[{"name":"errorMessage","type":["string","null"]}]}]}
> {code}
>
> When I use Avro in C# to parse this union schema JSON string, it is correct.
> [Schema.ParseJson() in
> C#|https://github.com/apache/avro/blob/master/lang/csharp/src/apache/main/Schema/Schema.cs#L203]
> But when I use Avro in Java to parse the union schema in Stream from C#,
> there is the following error message:
> {code:java}
> org.apache.avro.SchemaParseException: No type:
> {"type":[{"type":"record","name":"columnCount","namespace":"avro.test.header","fields":[{"name":"columnCount","type":"int"}]},{"type":"record","name":"errorMessage","namespace":"avro.test.header","fields":[{"name":"errorMessage","type":["string","null"]}]}]}org.apache.avro.SchemaParseException:
> No type:
> {"type":[{"type":"record","name":"columnCount","namespace":"avro.test.header","fields":[{"name":"columnCount","type":"int"}]},{"type":"record","name":"errorMessage","namespace":"avro.test.header","fields":[{"name":"errorMessage","type":["string","null"]}]}]}
> at org.apache.avro.Schema.getRequiredText(Schema.java:1784) at
> org.apache.avro.Schema.parse(Schema.java:1637) at
> org.apache.avro.Schema$Parser.parse(Schema.java:1425) at
> org.apache.avro.Schema$Parser.parse(Schema.java:1413) at
> org.apache.avro.file.DataFileStream.initialize(DataFileStream.java:130) at
> org.apache.avro.file.DataFileStream.<init>(DataFileStream.java:90) at
> avro.AvroService.read(AvroService.java:68) at
> avro.AvroService$1.onResponse(AvroService.java:144) at
> okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:519) at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> {code}
> I think this format of union schema should be supported in Java.
>
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