Ejemplo: operación de escritura por lote con el modelo de persistencia de objetos de AWS SDK for .NET

En el siguiente ejemplo de código C# se declaran las clases Book, Forum, Thread y Reply y se mapean a tablas de Amazon DynamoDB utilizando los atributos del modelo de persistencia de objetos.

A continuación, se utiliza DynamoDBContext para ilustrar las siguientes operaciones de escritura por lote:

• Objeto BatchWrite para colocar y eliminar elementos de libro de la tabla ProductCatalog.

• Objeto MultiTableBatchWrite para colocar y eliminar elementos de las tablas Forum y Thread.

Para obtener más información sobre las tablas que se utilizan en este ejemplo, consulte Creación de tablas y carga de datos para ejemplos de código en DynamoDB. Para obtener instrucciones paso a paso sobre cómo realizar las pruebas del ejemplo siguiente, consulte Ejemplos de código .NET.

nota

Los ejemplos que aparecen en esta sección no funcionan con .NET Core, ya que no es compatible con los métodos síncronos. Para obtener más información, consulte API asincrónicas de AWS para .NET.

ejemplo

using System;
using System.Collections.Generic;
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.DataModel;
using Amazon.Runtime;
using Amazon.SecurityToken;

namespace com.amazonaws.codesamples
{
    class HighLevelBatchWriteItem
    {
        private static AmazonDynamoDBClient client = new AmazonDynamoDBClient();

        static void Main(string[] args)
        {
            try
            {
                DynamoDBContext context = new DynamoDBContext(client);
                SingleTableBatchWrite(context);
                MultiTableBatchWrite(context);
            }
            catch (AmazonServiceException e) { Console.WriteLine(e.Message); }
            catch (Exception e) { Console.WriteLine(e.Message); }

            Console.WriteLine("To continue, press Enter");
            Console.ReadLine();
        }

        private static void SingleTableBatchWrite(DynamoDBContext context)
        {
            Book book1 = new Book
            {
                Id = 902,
                InPublication = true,
                ISBN = "902-11-11-1111",
                PageCount = "100",
                Price = 10,
                ProductCategory = "Book",
                Title = "My book3 in batch write"
            };
            Book book2 = new Book
            {
                Id = 903,
                InPublication = true,
                ISBN = "903-11-11-1111",
                PageCount = "200",
                Price = 10,
                ProductCategory = "Book",
                Title = "My book4 in batch write"
            };

            var bookBatch = context.CreateBatchWrite<Book>();
            bookBatch.AddPutItems(new List<Book> { book1, book2 });

            Console.WriteLine("Performing batch write in SingleTableBatchWrite().");
            bookBatch.Execute();
        }

        private static void MultiTableBatchWrite(DynamoDBContext context)
        {
            // 1. New Forum item.
            Forum newForum = new Forum
            {
                Name = "Test BatchWrite Forum",
                Threads = 0
            };
            var forumBatch = context.CreateBatchWrite<Forum>();
            forumBatch.AddPutItem(newForum);

            // 2. New Thread item.
            Thread newThread = new Thread
            {
                ForumName = "S3 forum",
                Subject = "My sample question",
                KeywordTags = new List<string> { "S3", "Bucket" },
                Message = "Message text"
            };

            DynamoDBOperationConfig config = new DynamoDBOperationConfig();
            config.SkipVersionCheck = true;
            var threadBatch = context.CreateBatchWrite<Thread>(config);
            threadBatch.AddPutItem(newThread);
            threadBatch.AddDeleteKey("some partition key value", "some sort key value");

            var superBatch = new MultiTableBatchWrite(forumBatch, threadBatch);
            Console.WriteLine("Performing batch write in MultiTableBatchWrite().");
            superBatch.Execute();
        }
    }

    [DynamoDBTable("Reply")]
    public class Reply
    {
        [DynamoDBHashKey] //Partition key
        public string Id
        {
            get; set;
        }

        [DynamoDBRangeKey] //Sort key
        public DateTime ReplyDateTime
        {
            get; set;
        }

        // Properties included implicitly.
        public string Message
        {
            get; set;
        }
        // Explicit property mapping with object persistence model attributes.
        [DynamoDBProperty("LastPostedBy")]
        public string PostedBy
        {
            get; set;
        }
        // Property to store version number for optimistic locking.
        [DynamoDBVersion]
        public int? Version
        {
            get; set;
        }
    }

    [DynamoDBTable("Thread")]
    public class Thread
    {
        // PK mapping.
        [DynamoDBHashKey]      //Partition key
        public string ForumName
        {
            get; set;
        }
        [DynamoDBRangeKey]      //Sort key
        public String Subject
        {
            get; set;
        }
        // Implicit mapping.
        public string Message
        {
            get; set;
        }
        public string LastPostedBy
        {
            get; set;
        }
        public int Views
        {
            get; set;
        }
        public int Replies
        {
            get; set;
        }
        public bool Answered
        {
            get; set;
        }
        public DateTime LastPostedDateTime
        {
            get; set;
        }
        // Explicit mapping (property and table attribute names are different.
        [DynamoDBProperty("Tags")]
        public List<string> KeywordTags
        {
            get; set;
        }
        // Property to store version number for optimistic locking.
        [DynamoDBVersion]
        public int? Version
        {
            get; set;
        }
    }

    [DynamoDBTable("Forum")]
    public class Forum
    {
        [DynamoDBHashKey]      //Partition key
        public string Name
        {
            get; set;
        }
        // All the following properties are explicitly mapped,
        // only to show how to provide mapping.
        [DynamoDBProperty]
        public int Threads
        {
            get; set;
        }
        [DynamoDBProperty]
        public int Views
        {
            get; set;
        }
        [DynamoDBProperty]
        public string LastPostBy
        {
            get; set;
        }
        [DynamoDBProperty]
        public DateTime LastPostDateTime
        {
            get; set;
        }
        [DynamoDBProperty]
        public int Messages
        {
            get; set;
        }
    }

    [DynamoDBTable("ProductCatalog")]
    public class Book
    {
        [DynamoDBHashKey] //Partition key
        public int Id
        {
            get; set;
        }
        public string Title
        {
            get; set;
        }
        public string ISBN
        {
            get; set;
        }
        public int Price
        {
            get; set;
        }
        public string PageCount
        {
            get; set;
        }
        public string ProductCategory
        {
            get; set;
        }
        public bool InPublication
        {
            get; set;
        }
    }
}