ExpectedAttributeValue - Amazon DynamoDB

Represents a condition to be compared with an attribute value. This condition can be used with DeleteItem, PutItem, or UpdateItem operations; if the comparison evaluates to true, the operation succeeds; if not, the operation fails. You can use ExpectedAttributeValue in one of two different ways:

Use AttributeValueList to specify one or more values to compare against an attribute. Use ComparisonOperator

{ "Value": { "S": "string", "N": "string", "B": "string", "SS": [], "NS": [], "BS": [], "M": { "property1": {}, "property2": {} }, "L": [], "NULL": true, "BOOL": true }, "Exists": true, "ComparisonOperator": "EQ", "AttributeValueList": [] }