How to Access Amazon Athena Data Using Entity Framework

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 Athena 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 Athena Entity Framework 6 assembly and the connection string.

   Authenticating to Amazon Athena

   To authorize Amazon Athena requests, provide the credentials for an administrator account or for an IAM user with custom permissions: Set AccessKey to the access key Id. Set SecretKey to the secret access key.

   Note: Though you can connect as the AWS account administrator, it is recommended to use IAM user credentials to access AWS services.

   Obtaining the Access Key

   To obtain the credentials for an IAM user, follow the steps below:

   1. Sign into the IAM console.
   2. In the navigation pane, select Users.
   3. To create or manage the access keys for a user, select the user and then select the Security Credentials tab.

   To obtain the credentials for your AWS root account, follow the steps below:

   1. Sign into the AWS Management console with the credentials for your root account.
   2. Select your account name or number and select My Security Credentials in the menu that is displayed.
   3. Click Continue to Security Credentials and expand the Access Keys section to manage or create root account access keys.

   Authenticating from an EC2 Instance

   If you are using the CData Data Provider for Amazon Athena 2018 from an EC2 Instance and have an IAM Role assigned to the instance, you can use the IAM Role to authenticate. To do so, set UseEC2Roles to true and leave AccessKey and SecretKey empty. The CData Data Provider for Amazon Athena 2018 will automatically obtain your IAM Role credentials and authenticate with them.

   Authenticating as an AWS Role

   In many situations it may be preferable to use an IAM role for authentication instead of the direct security credentials of an AWS root user. An AWS role may be used instead by specifying the RoleARN. This will cause the CData Data Provider for Amazon Athena 2018 to attempt to retrieve credentials for the specified role. If you are connecting to AWS (instead of already being connected such as on an EC2 instance), you must additionally specify the AccessKey and SecretKey of an IAM user to assume the role for. Roles may not be used when specifying the AccessKey and SecretKey of an AWS root user.

   Authenticating with MFA

   For users and roles that require Multi-factor Authentication, specify the MFASerialNumber and MFAToken connection properties. This will cause the CData Data Provider for Amazon Athena 2018 to submit the MFA credentials in a request to retrieve temporary authentication credentials. Note that the duration of the temporary credentials may be controlled via the TemporaryTokenDuration (default 3600 seconds).

   Connecting to Amazon Athena

   In addition to the AccessKey and SecretKey properties, specify Database, S3StagingDirectory and Region. Set Region to the region where your Amazon Athena data is hosted. Set S3StagingDirectory to a folder in S3 where you would like to store the results of queries.

   If Database is not set in the connection, the data provider connects to the default database set in Amazon Athena.

   <configuration> ... <connectionStrings> <add name="AmazonAthenaContext" connectionString="Offline=False;AccessKey='a123';SecretKey='s123';Region='IRELAND';Database='sampledb';S3StagingDirectory='s3://bucket/staging/';" providerName="System.Data.CData.AmazonAthena" /> </connectionStrings> <entityFramework> <providers> ... <provider invariantName="System.Data.CData.AmazonAthena" type="System.Data.CData.AmazonAthena.AmazonAthenaProviderServices, System.Data.CData.AmazonAthena.Entities.EF6" /> </providers> <entityFramework> </configuration> </code>
4. Add a reference to System.Data.CData.AmazonAthena.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 AmazonAthenaContext. 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 AmazonAthenaContext : DbContext { public AmazonAthenaContext() { } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // To remove the requests to the Migration History table Database.SetInitializer<AmazonAthenaContext>(null); // To remove the plural names modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } }
7. Create another .cs file and name it after the Amazon Athena entity you are retrieving, for example, Customers. 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("Customers")] public class Customers { [System.ComponentModel.DataAnnotations.Key] public System.String Name { get; set; } public System.String TotalDue { get; set; } }
8. Now that you have created an entity, add the entity to your context class: public DbSet<Customers> Customers { set; get; }
9. With the context and entity finished, you are now ready to query the data in a separate class. For example: AmazonAthenaContext context = new AmazonAthenaContext(); context.Configuration.UseDatabaseNullSemantics = true; var query = from line in context.Customers select line;