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Access Microsoft CDS Data with Entity Framework 6

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

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 Microsoft CDS 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 Microsoft CDS Entity Framework 6 assembly and the connection string.

    You can connect without setting any connection properties for your user credentials. Below are the minimum connection properties required to connect.

    • InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
    • OrganizationUrl: Set this to the organization URL you are connecting to, such as https://myorganization.crm.dynamics.com.
    • Tenant (optional): Set this if you wish to authenticate to a different tenant than your default. This is required to work with an organization not on your default Tenant.

    When you connect the Common Data Service OAuth endpoint opens in your default browser. Log in and grant permissions. The OAuth process completes automatically.

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