Dynamo DB Polymorphism (Feedback Requested)

[kiiadi]

In response to issue #832, this introduces a new @DynamoDBSubTyped annotation to describe known sub-types of a class along with a string-identifier for those types that is persisted to the Dynamo table and allows the sub-type information to be persisted at save and retrieved at load time.

Example usage:

@DynamoDBSubTyped({
	@SubType(name = "firstSubType", value = FirstSubType.class),
	@SubType(name = "secondSubType", value = SecondSubType.class)
})
class BaseClass { }

class FirstSubType extends BaseClass { }
class SecondSubType extends BaseClass { }

By default the type name is stored in a String field in Dynamo called "_type"; this can be customized by providing the "attributeName" property to the @DynamoDBSubTyped annotation. This attribute can refer to an property already on the object or if it doesn't exist as a property of the object it will be created in the dynamo db table. It must be of type java.lang.String.

The above example allows the following:

mapper.save(firstSubType);
mapper.save(secondSubType);

FirstSubType loadedFirstSubType = (FirstSubType) mapper.load(BaseClass.class, /*some id for firstSubType*/);

Also works with when scanning/querying:

List<BaseClass> objects = mapper.scan(BaseClass.class);
objects.forEach(o -> System.out.println(o.getClass())); 
/* prints FirstSubType.class, SecondSubType.class */

[pradeeptk304]

This is a useful feature, usage is also simple. When will this be merged?

[pluttrell]

@kiiadi Any update on when this might get merged and then released?

[pipoescomo]

Please merge.

[jeansossmeier]

+1

[siwonred]

+1

[avernonquantify]

+1

[junbong]

+1

[khayashi4337]

+1

[alexandredavi]

+1

[ojh3636]

+1

[billopark]

+1

[shimika]

+1

[ghost]

+1

[woldieJDI]

THE POWER OF THE SWOOSH COMPELS YOU TO MERGE!

[showmeyourcode]

+1

[sahlouls]

+1

[jackyjjc-canva]

Any update on when does this PR gets merge? @kiiadi

[gakinson]

Follow up on completion of this feature?

[dleffel]

Is this set to merge or is there any other problems?

[pan-con-jamon]

Hi! Any reason why this hasn't been merged already? It's the only lacking feature I need for my DynamoDB project

[adrG2]

Any update?

[millems]

Unfortunately this pull request doesn't have enough tests (either functional or performance) for the Java SDK team to merge as-is, and we haven't prioritized doing that testing, since a lot of people are very vocal about wanting us to focus on V2 of the SDK.

I've created a feature request for adding this feature to the V2 DynamoDB enhanced client: aws/aws-sdk-java-v2#1870. We're currently leaning towards just doing this with the enhanced client in V2, since that's much better tested and understood.

[debora-ito]

Closing this PR, we don't have plans to merge this DynamoDB Mapper feature at this point.