Amazon DynamoDB
开发人员指南 (API Version 2012-08-10)
AWS 服务或AWS文档中描述的功能,可能因地区/位置而异。点 击 Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

示例:使用适用于 .NET 的 AWS 开发工具包低级别 API 执行 CRUD 操作

以下 C# 代码示例介绍对项目的 CRUD 操作。示例介绍将项目添加到 ProductCatalog 表、对其进行检索、执行各个更新以及最终删除项目。如果您执行创建表并加载示例数据中的步骤,则您应已创建 ProductCatalog 表。您还能够以编程方式创建这些示例表。有关更多信息,请参阅 使用适用于 .NET 的 AWS 开发工具包创建示例表和上传数据

有关测试以下示例的分步说明,请参阅.NET 代码示例

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using System; using System.Collections.Generic; using Amazon.DynamoDBv2; using Amazon.DynamoDBv2.Model; using Amazon.Runtime; using Amazon.SecurityToken; namespace com.amazonaws.codesamples { class LowLevelItemCRUDExample { private static string tableName = "ProductCatalog"; private static AmazonDynamoDBClient client = new AmazonDynamoDBClient(); static void Main(string[] args) { try { CreateItem(); RetrieveItem(); // Perform various updates. UpdateMultipleAttributes(); UpdateExistingAttributeConditionally(); // Delete item. DeleteItem(); Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } catch (Exception e) { Console.WriteLine(e.Message); Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } } private static void CreateItem() { var request = new PutItemRequest { TableName = tableName, Item = new Dictionary<string, AttributeValue>() { { "Id", new AttributeValue { N = "1000" }}, { "Title", new AttributeValue { S = "Book 201 Title" }}, { "ISBN", new AttributeValue { S = "11-11-11-11" }}, { "Authors", new AttributeValue { SS = new List<string>{"Author1", "Author2" } }}, { "Price", new AttributeValue { N = "20.00" }}, { "Dimensions", new AttributeValue { S = "8.5x11.0x.75" }}, { "InPublication", new AttributeValue { BOOL = false } } } }; client.PutItem(request); } private static void RetrieveItem() { var request = new GetItemRequest { TableName = tableName, Key = new Dictionary<string, AttributeValue>() { { "Id", new AttributeValue { N = "1000" } } }, ProjectionExpression = "Id, ISBN, Title, Authors", ConsistentRead = true }; var response = client.GetItem(request); // Check the response. var attributeList = response.Item; // attribute list in the response. Console.WriteLine("\nPrinting item after retrieving it ............"); PrintItem(attributeList); } private static void UpdateMultipleAttributes() { var request = new UpdateItemRequest { Key = new Dictionary<string, AttributeValue>() { { "Id", new AttributeValue { N = "1000" } } }, // Perform the following updates: // 1) Add two new authors to the list // 1) Set a new attribute // 2) Remove the ISBN attribute ExpressionAttributeNames = new Dictionary<string, string>() { {"#A","Authors"}, {"#NA","NewAttribute"}, {"#I","ISBN"} }, ExpressionAttributeValues = new Dictionary<string, AttributeValue>() { {":auth",new AttributeValue { SS = {"Author YY", "Author ZZ"} }}, {":new",new AttributeValue { S = "New Value" }} }, UpdateExpression = "ADD #A :auth SET #NA = :new REMOVE #I", TableName = tableName, ReturnValues = "ALL_NEW" // Give me all attributes of the updated item. }; var response = client.UpdateItem(request); // Check the response. var attributeList = response.Attributes; // attribute list in the response. // print attributeList. Console.WriteLine("\nPrinting item after multiple attribute update ............"); PrintItem(attributeList); } private static void UpdateExistingAttributeConditionally() { var request = new UpdateItemRequest { Key = new Dictionary<string, AttributeValue>() { { "Id", new AttributeValue { N = "1000" } } }, ExpressionAttributeNames = new Dictionary<string, string>() { {"#P", "Price"} }, ExpressionAttributeValues = new Dictionary<string, AttributeValue>() { {":newprice",new AttributeValue { N = "22.00" }}, {":currprice",new AttributeValue { N = "20.00" }} }, // This updates price only if current price is 20.00. UpdateExpression = "SET #P = :newprice", ConditionExpression = "#P = :currprice", TableName = tableName, ReturnValues = "ALL_NEW" // Give me all attributes of the updated item. }; var response = client.UpdateItem(request); // Check the response. var attributeList = response.Attributes; // attribute list in the response. Console.WriteLine("\nPrinting item after updating price value conditionally ............"); PrintItem(attributeList); } private static void DeleteItem() { var request = new DeleteItemRequest { TableName = tableName, Key = new Dictionary<string, AttributeValue>() { { "Id", new AttributeValue { N = "1000" } } }, // Return the entire item as it appeared before the update. ReturnValues = "ALL_OLD", ExpressionAttributeNames = new Dictionary<string, string>() { {"#IP", "InPublication"} }, ExpressionAttributeValues = new Dictionary<string, AttributeValue>() { {":inpub",new AttributeValue { BOOL = false }} }, ConditionExpression = "#IP = :inpub" }; var response = client.DeleteItem(request); // Check the response. var attributeList = response.Attributes; // Attribute list in the response. // Print item. Console.WriteLine("\nPrinting item that was just deleted ............"); PrintItem(attributeList); } private static void PrintItem(Dictionary<string, AttributeValue> attributeList) { foreach (KeyValuePair<string, AttributeValue> kvp in attributeList) { string attributeName = kvp.Key; AttributeValue value = kvp.Value; Console.WriteLine( attributeName + " " + (value.S == null ? "" : "S=[" + value.S + "]") + (value.N == null ? "" : "N=[" + value.N + "]") + (value.SS == null ? "" : "SS=[" + string.Join(",", value.SS.ToArray()) + "]") + (value.NS == null ? "" : "NS=[" + string.Join(",", value.NS.ToArray()) + "]") ); } Console.WriteLine("************************************************"); } } }