Amazon AWS SDK Podręcznik Użytkownika Pobierz pdf (Strona 66)

// using Amazon.DynamoDBv2;

// using Amazon.DynamoDBv2.Model;

var client = new AmazonDynamoDBClient();

var request = new UpdateItemRequest

{

TableName = "ProductCatalog",

Key = new Dictionary<string,AttributeValue>

{

{ "Id", new AttributeValue { N = "301" } }

ExpressionAttributeNames = new Dictionary<string, string>

{

{ "#title", "Title" }

ExpressionAttributeValues = new Dictionary<string, AttributeValue>

{

{ ":newproduct", new AttributeValue { S = "18\" Girl's Bike" } }

UpdateExpression = "SET #title = :newproduct"

};

client.UpdateItem(request);

In the preceding example, the ExpressionAttributeNames property specifies the placeholder #title

to represent the Title attribute.The ExpressionAttributeValues property specifies the placeholder

:newproduct to represent the value 18" Girl's Bike.The UpdateExpression property specifies

to change #title (Title) to :newproduct (18" Girl's Bike).

Delete an Item by Using Expressions

The following example features the Amazon.DynamoDBv2.AmazonDynamoDBClient.DeleteItem

method and a set of expressions to delete the item with Id of 301, but only if the item's Title is

18-Bicycle 301.

// using Amazon.DynamoDBv2;

// using Amazon.DynamoDBv2.Model;

var client = new AmazonDynamoDBClient();

var request = new DeleteItemRequest

{

TableName = "ProductCatalog",

Key = new Dictionary<string,AttributeValue>

{

{ "Id", new AttributeValue { N = "301" } }

ExpressionAttributeNames = new Dictionary<string, string>

{

{ "#title", "Title" }

ExpressionAttributeValues = new Dictionary<string, AttributeValue>

{

{ ":product", new AttributeValue { S = "18-Bicycle 301" } }

ConditionExpression = "#title = :product"

};

client.DeleteItem(request);

Version v2.0.0

AWS SDK for .NET Developer Guide

Using Expressions with DynamoDB

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