Access Twitter Data with Entity Framework 6

Entity Framework is an object-relational mapping framework that can be used to work with data as objects. While you can run the ADO.NET Entity Data Model wizard in Visual Studio to handle generating the Entity Model, this approach, the model-first approach, can put you at a disadvantage if there are changes in your data source or if you want more control over how the entities operate. In this article you will complete the code-first approach to accessing Twitter data using the CData ADO.NET Provider.

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 Twitter Entity Framework 6 assembly and the connection string.

   All tables require authentication. You can connect using your User and Password or OAuth. To authenticate using OAuth, you can use the embedded OAuthClientId, OAuthClientSecret, and CallbackURL or you can register an app to obtain your own.

   If you intend to communicate with Twitter only as the currently authenticated user, then you can obtain the OAuthAccessToken and OAuthAccessTokenSecret directly by registering an app.

   See the Getting Started chapter in the help documentation for a guide to using OAuth.

   <configuration> ... <connectionStrings> <add name="TwitterContext" connectionString="Offline=False;InitiateOAuth=GETANDREFRESH" providerName="System.Data.CData.Twitter" /> </connectionStrings> <entityFramework> <providers> ... <provider invariantName="System.Data.CData.Twitter" type="System.Data.CData.Twitter.TwitterProviderServices, System.Data.CData.Twitter.Entities.EF6" /> </providers> <entityFramework> </configuration> </code>
4. Add a reference to System.Data.CData.Twitter.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 TwitterContext. 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 TwitterContext : DbContext { public TwitterContext() { } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // To remove the requests to the Migration History table Database.SetInitializer<TwitterContext>(null); // To remove the plural names modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } }
7. Create another .cs file and name it after the Twitter entity you are retrieving, for example, Tweets. 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("Tweets")] public class Tweets { [System.ComponentModel.DataAnnotations.Key] public System.String From_User_Name { get; set; } public System.String Retweet_Count { get; set; } }
8. Now that you have created an entity, add the entity to your context class: public DbSet<Tweets> Tweets { set; get; }
9. With the context and entity finished, you are now ready to query the data in a separate class. For example: TwitterContext context = new TwitterContext(); context.Configuration.UseDatabaseNullSemantics = true; var query = from line in context.Tweets select line;