com.amazonaws.services.dynamodbv2.datamodeling

Class UpdateExpressionGenerator

java.lang.Object

com.amazonaws.services.dynamodbv2.datamodeling.UpdateExpressionGenerator

public class UpdateExpressionGenerator
extends Object

This class will contain logic for converting an update object that customer has passed-in into low level update expression and corresponding expression attribute maps. Currently this entails generating a string that can be used as a substitution token in the updateExpression and insert corresponding attribute name/value in the expressionAttributeNameMap/expressionAttributeValueMap For ex: Attribute will be converted to: updateExpression = "SET #5d810=:5d810" and expressionAttributeNameMap = {{#5d810, "stringAttribute"},...} expressionAttributeValueMap = {{:5d810, {S: "sdkAttributeStringValue"}},...} Null valued attributes will be converted to REMOVE expressions similarly and appended to the updateExpression We use deterministic token generation logic to ensure request contents remain same across retried transactionWrite calls. This will help in ensuring idempotency across retried calls. Read more on idempotency of transactionWrite API here: https://docs.aws.amazon.com/en_us/amazondynamodb/latest/APIReference/API_TransactWriteItems.html#DDB-TransactWriteItems-request-ClientRequestToken

Constructor Summary

Constructors

Constructor and Description
UpdateExpressionGenerator()

Method Summary

Modifier and Type	Method and Description
String	generateUpdateExpressionAndUpdateAttributeMaps(Map<String,String> expressionAttributeNamesMap, Map<String,AttributeValue> expressionsAttributeValuesMap, Map<String,AttributeValue> nonKeyNonNullAttributeValueMap, List<String> nullValuedNonKeyAttributeNames) Merge nonKeyAttributes along with any condition expression attributes and generate corresponding update expression

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UpdateExpressionGenerator

public UpdateExpressionGenerator()

Method Detail

generateUpdateExpressionAndUpdateAttributeMaps

public String generateUpdateExpressionAndUpdateAttributeMaps(Map<String,String> expressionAttributeNamesMap,
                                                             Map<String,AttributeValue> expressionsAttributeValuesMap,
                                                             Map<String,AttributeValue> nonKeyNonNullAttributeValueMap,
                                                             List<String> nullValuedNonKeyAttributeNames)

Merge nonKeyAttributes along with any condition expression attributes and generate corresponding update expression