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Set explicit default null values for nullable fields in generated schemas #294
Set explicit default null values for nullable fields in generated schemas #294
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Need this PR merged, please! :) |
Sorry for the slow response - I'll try to take a look this evening. |
I agree this behaviour should be available but I also think it should be optional - so keep the existing |
@bplommer thanks for looking into this. |
I guess it's also possible to use magnolia's param default value extractor and have more generic annotation: case class ABC(
@AvroDefaultValue a: Int = 5,
b: Option[String],
@AvroDefaultValue c: Option[Long] = None
) =>
With implementation like: ...
param.annotations.collectFirst {
case adv: AvroDefaultValue =>
param.default match {
case Some(defaultValue) =>
param.typeclass.encode(defaultValue) match {
case Left(err) => throw err.throwable
case Right(value) =>
// TODO: Handle other unions except for [null, ???]
if (schema.isNullable && value == null)
Schema.Field.NULL_DEFAULT_VALUE
else if (schema.isNullable)
throw new Exception(
s"For optional fields only supported default value is None, field ${param.label} has default value $defaultValue."
)
else value
}
case None =>
throw new Exception(
s"Missing default value for a field ${param.label} annotated with $adv."
)
}
}.orNull
... Which kinda works, but because in avro default values for union fields have to correspond to the first schema in the union would have to either:
|
This looks great, thanks!
I think it's best to leave this as is to avoid too much complexity. @vlovgr any thoughts on this before I merge? |
Agreed, let's keep the derivation module as simple as possible. |
Some schema consumers require explicitly set
"default": null
for the "nullable union field".Related: AVRO-1803