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https://issues.apache.org/jira/browse/AVRO-2775?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17100865#comment-17100865
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Ryan Skraba commented on AVRO-2775:
-----------------------------------
Hello! Just a quick point of view on this -- if I understand correctly, the
goal is to be able to pass a POJO (that Jackson can handle) as a property
(metadata) value in a schema?
The code that would be exposed to the user would be something like this:
{code}
Schema s = ...
s.addProp("age", new Age(9));
...
// later
Map m = (Map) s.getObjectProp("age")
{code}
I don't see this being a great idea, as opposed to the current behaviour, which
is to only support a specified list of permitted java types, and throw an
exception otherwise.
My reasoning is:
# Turning a POJO into JSON is Jackson-specific behaviour and I'm not sure we
want to tie Avro behaviour to it. It might not be a big deal (if we're not
planning on replacing Jackson any time soon).
# Currently, what we put into a property value is also what we'll get out...
and I think will always be the expected behaviour for the user!
If we maintain the current behaviour, the user is responsible for turning the
POJO {{Age}} into the permitted java types, which seems reasonable to me.
> JacksonUtils: exception when calling toJsonNode()
> --------------------------------------------------
>
> Key: AVRO-2775
> URL: https://issues.apache.org/jira/browse/AVRO-2775
> Project: Apache Avro
> Issue Type: Bug
> Components: java
> Affects Versions: 1.9.2
> Reporter: Andy Le
> Priority: Major
>
> I've got a simple test as followed
> {code:java}
> public class TestJacksonUtils {
> public static class Age{
> public int value = 9;
> }
> @Test
> public void testToJson(){
> Map<String, Object> kv = new HashMap<>();
> kv.put("age", 9);
> JsonNode node1 = JacksonUtils.toJsonNode(kv); // -> This is OK
> Object obj = new Age();
> JsonNode node2 = JacksonUtils.toJsonNode(obj); // -> This will trigger an
> exception
> }
> }
> {code}
> When I ran the test:
> {noformat}
> org.apache.avro.AvroRuntimeException: Unknown datum class: class
> org.apache.avro.util.internal.TestJacksonUtils$Age
> at
> org.apache.avro.util.internal.JacksonUtils.toJson(JacksonUtils.java:87)
> at
> org.apache.avro.util.internal.JacksonUtils.toJsonNode(JacksonUtils.java:48)
> at
> org.apache.avro.util.internal.TestJacksonUtils.testToJson(TestJacksonUtils.java:20)
> {noformat}
> I've read the code & tests for JacksonUtils. Instead of raising exceptions at
> [line
> #87|https://github.com/apache/avro/blob/master/lang/java/avro/src/main/java/org/apache/avro/util/internal/JacksonUtils.java#L87],
> I see we can auto convert objects into maps, every thing's gonna fine.
> My question is:
> - Is raising exception acceptable?
> - Any other way to have `toJsonNode` for general objects?
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