ex-ratt commented on PR #2887:
URL: https://github.com/apache/avro/pull/2887#issuecomment-2112901411
Sorry for barging into the discussion uninvited, but I am following this PR,
since I like the idea of such an annotation. If I understood the comments on
the original issue correctly, then the annotation should not only allow to
specify the namespace, but also the name of a record/enum - hence the name
`@AvroTypeName` for the annotation instead of `@AvroNamespace`. The following
suggestions are from Oscar's comment on the issue, I just adjusted the name of
the annotation:
1. `@AvroTypeName("simpleOrFullName")` for a named type would set its name,
optionally with namespace
2. `@AvroTypeName(value="simpleName", namespace="my.space")` for a named
type would set its name and namespace
3. `@AvroTypeName(namespace="my.space")` for a named type would set only the
namespace and let the name be inferred
I guess this is what @opwvhk is referring to.
On a related note: I really like the idea of this kind of annotation,
because namespace & name of a record schema can be independent from package &
name of the corresponding class. However, it does not end there: `ReflectData`
and `ReflectDatumReader` are not able to deserialize data when the schema of a
record/enum has a changed name or namespace. Currently, it assumes that the
class can be inferred from namespace & name of a record, see
`SpecificData.getClass(Schema)`, which is used by
`SpecificData.newRecord(Object, Schema)` (and `ReflectData` derives from
`SpecificData`). I stumbled upon this issue this week when trying to implement
an `@AvroNamespace` annotation myself.
What solved this issue for me was to add a property to the generated schema
(`SpecificData.CLASS_PROP`, which is already used to specify classes for Avro
arrays) and override `ReflectData.getClass(Schema)` to read this property (and
cache the loaded class, just like `ReflectData.getClassProp(Schema,String)`).
I would appreciate an official solution, so I can throw away my code which
may break with new versions of the Avro library.
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