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Access Amazon DynamoDB Data with Entity Framework 6



This article shows how to access Amazon DynamoDB data using an Entity Framework code-first approach. Entity Framework 6 is available in .NET 4.5 and above.

Microsoft Entity Framework serves as an object-relational mapping framework for working with data represented as objects. Although Visual Studio offers the ADO.NET Entity Data Model wizard to automatically generate the Entity Model, this model-first approach may present challenges when your data source undergoes changes or when you require greater control over entity operations. In this article, we will delve into the code-first approach for accessing Amazon DynamoDB data through the CData ADO.NET Provider, providing you with more flexibility and control.

  1. Open Visual Studio and create a new Windows Form Application. This article uses a C# project with .NET 4.5.
  2. Run the command 'Install-Package EntityFramework' in the Package Manger Console in Visual Studio to install the latest release of Entity Framework.
  3. Modify the App.config file in the project to add a reference to the Amazon DynamoDB Entity Framework 6 assembly and the connection string.

    The connection to Amazon DynamoDB is made using your AccessKey, SecretKey, and optionally your Domain and Region. Your AccessKey and SecretKey can be obtained on the security credentials page for your Amazon Web Services account. Your Region will be displayed in the upper left-hand corner when you are logged into DynamoDB.

    <configuration> ... <connectionStrings> <add name="AmazonDynamoDBContext" connectionString="Offline=False;Access Key=xxx;Secret Key=xxx;Domain=amazonaws.com;Region=OREGON;" providerName="System.Data.CData.AmazonDynamoDB" /> </connectionStrings> <entityFramework> <providers> ... <provider invariantName="System.Data.CData.AmazonDynamoDB" type="System.Data.CData.AmazonDynamoDB.AmazonDynamoDBProviderServices, System.Data.CData.AmazonDynamoDB.Entities.EF6" /> </providers> <entityFramework> </configuration> </code>
  4. Add a reference to System.Data.CData.AmazonDynamoDB.Entities.EF6.dll, located in the lib -> 4.0 subfolder in the installation directory.
  5. Build the project at this point to ensure everything is working correctly. Once that's done, you can start coding using Entity Framework.
  6. Add a new .cs file to the project and add a class to it. This will be your database context, and it will extend the DbContext class. In the example, this class is named AmazonDynamoDBContext. The following code example overrides the OnModelCreating method to make the following changes:
    • Remove PluralizingTableNameConvention from the ModelBuilder Conventions.
    • Remove requests to the MigrationHistory table.
    using System.Data.Entity; using System.Data.Entity.Infrastructure; using System.Data.Entity.ModelConfiguration.Conventions; class AmazonDynamoDBContext : DbContext { public AmazonDynamoDBContext() { } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // To remove the requests to the Migration History table Database.SetInitializer<AmazonDynamoDBContext>(null); // To remove the plural names modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } }
  7. Create another .cs file and name it after the Amazon DynamoDB entity you are retrieving, for example, Lead. In this file, define both the Entity and the Entity Configuration, which will resemble the example below: using System.Data.Entity.ModelConfiguration; using System.ComponentModel.DataAnnotations.Schema; [System.ComponentModel.DataAnnotations.Schema.Table("Lead")] public class Lead { [System.ComponentModel.DataAnnotations.Key] public System.String Industry { get; set; } public System.String Revenue { get; set; } }
  8. Now that you have created an entity, add the entity to your context class: public DbSet<Lead> Lead { set; get; }
  9. With the context and entity finished, you are now ready to query the data in a separate class. For example: AmazonDynamoDBContext context = new AmazonDynamoDBContext(); context.Configuration.UseDatabaseNullSemantics = true; var query = from line in context.Lead select line;