Amazon DynamoDB
開発者ガイド (API バージョン 2012-08-10)

例: AWS SDK for .NET ドキュメントモデルを使用した CRUD オペレーション

次の C# コード例は、次のアクションを実行します。

  • ProductCatalog テーブルで書籍項目を作成します。

  • 書籍項目を取り出します。

  • 書籍項目を更新します。このコード例は、新しい属性を追加して既存の属性を更新する、通常の更新を示しています。また、既存の価格とコードで指定されている価格が一致する場合のみ書籍の価格を更新する、条件付き更新も示しています。

  • 書籍項目を削除します。

次のサンプルをテストするための詳しい手順については、「.NET コードサンプル」を参照してください。

using System; using System.Collections.Generic; using System.Linq; using Amazon.DynamoDBv2; using Amazon.DynamoDBv2.DocumentModel; using Amazon.Runtime; namespace com.amazonaws.codesamples { class MidlevelItemCRUD { private static AmazonDynamoDBClient client = new AmazonDynamoDBClient(); private static string tableName = "ProductCatalog"; // The sample uses the following id PK value to add book item. private static int sampleBookId = 555; static void Main(string[] args) { try { Table productCatalog = Table.LoadTable(client, tableName); CreateBookItem(productCatalog); RetrieveBook(productCatalog); // Couple of sample updates. UpdateMultipleAttributes(productCatalog); UpdateBookPriceConditionally(productCatalog); // Delete. DeleteBook(productCatalog); Console.WriteLine("To continue, press Enter"); Console.ReadLine(); } catch (AmazonDynamoDBException e) { Console.WriteLine(e.Message); } catch (AmazonServiceException e) { Console.WriteLine(e.Message); } catch (Exception e) { Console.WriteLine(e.Message); } } // Creates a sample book item. private static void CreateBookItem(Table productCatalog) { Console.WriteLine("\n*** Executing CreateBookItem() ***"); var book = new Document(); book["Id"] = sampleBookId; book["Title"] = "Book " + sampleBookId; book["Price"] = 19.99; book["ISBN"] = "111-1111111111"; book["Authors"] = new List<string> { "Author 1", "Author 2", "Author 3" }; book["PageCount"] = 500; book["Dimensions"] = "8.5x11x.5"; book["InPublication"] = new DynamoDBBool(true); book["InStock"] = new DynamoDBBool(false); book["QuantityOnHand"] = 0; productCatalog.PutItem(book); } private static void RetrieveBook(Table productCatalog) { Console.WriteLine("\n*** Executing RetrieveBook() ***"); // Optional configuration. GetItemOperationConfig config = new GetItemOperationConfig { AttributesToGet = new List<string> { "Id", "ISBN", "Title", "Authors", "Price" }, ConsistentRead = true }; Document document = productCatalog.GetItem(sampleBookId, config); Console.WriteLine("RetrieveBook: Printing book retrieved..."); PrintDocument(document); } private static void UpdateMultipleAttributes(Table productCatalog) { Console.WriteLine("\n*** Executing UpdateMultipleAttributes() ***"); Console.WriteLine("\nUpdating multiple attributes...."); int partitionKey = sampleBookId; var book = new Document(); book["Id"] = partitionKey; // List of attribute updates. // The following replaces the existing authors list. book["Authors"] = new List<string> { "Author x", "Author y" }; book["newAttribute"] = "New Value"; book["ISBN"] = null; // Remove it. // Optional parameters. UpdateItemOperationConfig config = new UpdateItemOperationConfig { // Get updated item in response. ReturnValues = ReturnValues.AllNewAttributes }; Document updatedBook = productCatalog.UpdateItem(book, config); Console.WriteLine("UpdateMultipleAttributes: Printing item after updates ..."); PrintDocument(updatedBook); } private static void UpdateBookPriceConditionally(Table productCatalog) { Console.WriteLine("\n*** Executing UpdateBookPriceConditionally() ***"); int partitionKey = sampleBookId; var book = new Document(); book["Id"] = partitionKey; book["Price"] = 29.99; // For conditional price update, creating a condition expression. Expression expr = new Expression(); expr.ExpressionStatement = "Price = :val"; expr.ExpressionAttributeValues[":val"] = 19.00; // Optional parameters. UpdateItemOperationConfig config = new UpdateItemOperationConfig { ConditionalExpression = expr, ReturnValues = ReturnValues.AllNewAttributes }; Document updatedBook = productCatalog.UpdateItem(book, config); Console.WriteLine("UpdateBookPriceConditionally: Printing item whose price was conditionally updated"); PrintDocument(updatedBook); } private static void DeleteBook(Table productCatalog) { Console.WriteLine("\n*** Executing DeleteBook() ***"); // Optional configuration. DeleteItemOperationConfig config = new DeleteItemOperationConfig { // Return the deleted item. ReturnValues = ReturnValues.AllOldAttributes }; Document document = productCatalog.DeleteItem(sampleBookId, config); Console.WriteLine("DeleteBook: Printing deleted just deleted..."); PrintDocument(document); } private static void PrintDocument(Document updatedDocument) { foreach (var attribute in updatedDocument.GetAttributeNames()) { string stringValue = null; var value = updatedDocument[attribute]; if (value is Primitive) stringValue = value.AsPrimitive().Value.ToString(); else if (value is PrimitiveList) stringValue = string.Join(",", (from primitive in value.AsPrimitiveList().Entries select primitive.Value).ToArray()); Console.WriteLine("{0} - {1}", attribute, stringValue); } } } }