Entity Mapping Reference

This document provides detailed information about entity mapping in DynamoDB Enhanced Client.

@DynamoDbBean Annotation

The @DynamoDbBean annotation marks a class as a DynamoDB entity:

@DynamoDbBean
public class Customer {
    // Class implementation
}

Field Annotations

@DynamoDbPartitionKey

Marks a field as the partition key:

@DynamoDbPartitionKey
public String getCustomerId() {
    return customerId;
}

@DynamoDbSortKey

Marks a field as the sort key (used with composite keys):

@DynamoDbSortKey
@DynamoDbAttribute("order_id")
public String getOrderId() {
    return orderId;
}

@DynamoDbAttribute

Maps a field to a DynamoDB attribute with custom name:

@DynamoDbAttribute("customer_name")
public String getName() {
    return name;
}

@DynamoDbSecondaryPartitionKey

Marks a field as a partition key for a Global Secondary Index:

@DynamoDbSecondaryPartitionKey(indexNames = "category-index")
public String getCategory() {
    return category;
}

@DynamoDbSecondarySortKey

Marks a field as a sort key for a Global Secondary Index:

@DynamoDbSecondarySortKey(indexNames = "category-index")
public BigDecimal getPrice() {
    return price;
}

@DynamoDbConvertedBy

Custom attribute conversion:

@DynamoDbConvertedBy(LocalDateTimeConverter.class)
public LocalDateTime getCreatedAt() {
    return createdAt;
}

Supported Data Types

The enhanced client automatically handles the following data types:

String → S (String)
Integer, Long → N (Number)
BigDecimal → N (Number)
Boolean → BOOL
LocalDateTime → S (ISO-8601 format)
LocalDate → S (ISO-8601 format)
UUID → S (String)
Enum → S (String representation)
Custom types with converters

Custom Converters

Create custom converters for complex data types:

public class LocalDateTimeConverter extends AttributeConverter<LocalDateTime, String> {

    @Override
    public String transformFrom(LocalDateTime input) {
        return input.toString();
    }

    @Override
    public LocalDateTime transformTo(String input) {
        return LocalDateTime.parse(input);
    }

    @Override
    public AttributeValue transformToAttributeValue(String input) {
        return AttributeValue.builder().s(input).build();
    }

    @Override
    public String transformFromAttributeValue(AttributeValue attributeValue) {
        return attributeValue.s();
    }
}

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