Beispiel: Batch-Schreibvorgang mit dem AWS SDK for .NET Modell der Objektpersistenz

Im folgenden C#-Codebeispiel werden die Klassen Book, Forum, Thread und Reply deklariert und unter Verwendung der Attribute des Object-Persistence-Modells Amazon-DynamoDB-Tabellen zugewiesen.

Anschließend verwendet das Beispiel den DynamoDBContext, um die folgenden Batchschreiboperationen darzustellen.

• BatchWrite-Objekt, um Book-Elemente in der Tabelle ProductCatalog abzulegen und aus dieser zu löschen.

• MultiTableBatchWrite-Objekt, um Elemente in den Tabellen Forum und Thread abzulegen und aus diesen zu löschen.

Weitere Informationen zu den hier verwendeten Tabellen finden Sie unter Erstellen von Tabellen und Laden von Daten für Codebeispiele in DynamoDB. step-by-step Anweisungen zum Testen des folgenden Beispiels finden Sie unter. NETCodebeispiele.

Anmerkung

Das folgende Beispiel funktioniert nicht mit. NETcore, weil es keine synchronen Methoden unterstützt. Weitere Informationen finden Sie unter AWS asynchron APIs für. NET.

Beispiel

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;
        }
    }
}