DynamoDB Mapper: Add attribute converter annotation

[tznd-amazon]

Describe the feature

An @ConvertedBy annotation for attributes that the generator can use without defining the entire ItemConverter

Is your feature request related to a problem?

If would be great if we didn't need to define the entire Item converter when just one attribute needs a custom value converter.

Currently as documented with the DynamoDB Mapper when a custom item converter is needed a value converter must be created and then an ItemConverter needs to be created for the entire model. If I could annotate one attribute and the generator would honor it, it would save a lot of boilerplate.

Proposed Solution

@DynamoDbItem
data class Employee(
    @DynamoDbPartitionKey
    val id: Int,
    
    val name: String,
    val role: String,

    # Proposed Annotation
    @ConvertedBy(UuidValueConverter::class)
    val workstationId: Uuid,
)


public val UuidValueConverter = object : ValueConverter<Uuid> {
    override fun convertFrom(to: AttributeValue): Uuid = 
        Uuid.parseHex(to.asS())
        
    override fun convertTo(from: Uuid): AttributeValue = 
        AttributeValue.S(from.toHexString())
}

Describe alternative solutions or features you've considered

No response

Acknowledge

• I may be able to implement this feature request

AWS SDK for Kotlin version

1.3.66-beta

Platform (JVM/JS/Native)

JVM

Operating system and version

AL2023

[lauzadis]

Thanks for this feature request, we've identified the same QoL improvement and are already tracking it!