DynamoDb Kotlin Module

Kotlin Module for the v2 dynamodb-enhanced SDK.

Adapting an idiomatic kotlin data model for use with the v2 dynamodb mapper is a pain, and full of compromises; data classes emulate a bean, which nullifies much of the advantages of data classes. This module provides a new TableSchema implementation that adds support for kotlin data classes.

properties can be immutable; i.e. val is allowed
properties don't need default values
new annotations work directly on kotlin properties, rather than their getters

Install

Follow the instructions on Jitpack.

Quickstart

// create a data class model, making sure to give it a partition key
data class Cat(
    @DynamoKtPartitionKey val name: String,
    val lives: Int = 9,
)

// use the new table schema provided by this module to init the table mapper
val tableSchema = DataClassTableSchema(Cat::class)
val cats = DynamoDbEnhancedClient.create().table("cats", tableScema)

// use the table mapper however you want!!
cats.createTable()
cats.putItem(Cat("Toggles"))

Annotations

The schema uses a new set of property-friendly annotations.

data class Appointment(
    @DynamoKtPartitionKey  // partition key for main index
    @DynamoKtAttribute(name = "owner_id")  // optionally rename the attribute
    val ownerId: UUID,
    
    @DynamoKtSortKey  // sort key for main index
    val id: UUID,
    
    @DynamoKtSecondaryPartitionKey(indexNames = ["names"])  // partition key for secondary indices
    val lastName: String,
    
    @DynamoKtSecondarySortKey(indexNames = ["names"])  // sort key for secondary indices
    val firstName: String,
    
    @DynamoKtConverted(InstantAsLongAttributeConverter::class)  // override the attribute converter
    val expires: Instant?
)

Enhanced Table Creator

The DynamoDbTable.createTable() method provided in the V2 SDK ignores all the indices defined by your annotations, which can result in some "surprising behaviour".

With this plugin, you can now use the DynamoDbTable.createTableWithIndices() extension method; using reasonable defaults to fill whatever gaps exist in the table metadata.

data class Person(
    @DynamoKtPartitionKey val id: Int,
    @DynamoKtSecondaryPartitionKey(indexNames = ["names"]) val name: String,
    val dob: Instant
)

val schema = DataClassTableSchema(Person::class)
val table = DynamoDbEnhancedClient.create().table("people", schema)

table.createTableWithIndices()

Samples

See the Samples

cooco119 / dynamodb-kotlin-module