AWS SDK Version 3 for .NET
API Reference

AWS services or capabilities described in AWS Documentation may vary by region/location. Click Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

Instantiates ExpectedAttributeValue with the parameterized properties

Namespace: Amazon.DynamoDBv2.Model
Assembly: AWSSDK.DynamoDBv2.dll
Version: 3.x.y.z


public ExpectedAttributeValue(
         Boolean exists
Type: System.Boolean

Causes DynamoDB to evaluate the value before attempting a conditional operation: If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException. If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException. The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied. DynamoDB returns a ValidationException if: Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.) Exists is false but you also provide a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

Version Information

.NET Standard:
Supported in: 1.3

.NET Framework:
Supported in: 4.5, 4.0, 3.5

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms

Supported Versions: 4.6 and above
Supported Platforms: Android, iOS, Standalone