How to Access Azure Data Catalog 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 Azure Data Catalog 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 Azure Data Catalog Entity Framework 6 assembly and the connection string.

   You can optionally set the following to read the different catalog data returned from Azure Data Catalog.

   <>CatalogName: Set this to the CatalogName associated with your Azure Data Catalog. To get your Catalog name, navigate to your Azure Portal home page > Data Catalog > Catalog Name

   Connect Using OAuth Authentication

   You must use OAuth to authenticate with Azure Data Catalog. OAuth requires the authenticating user to interact with Azure Data Catalog using the browser. For more information, refer to the OAuth section in the help documentation.

   <configuration>
    ... 
    <connectionStrings>
    <add name="AzureDataCatalogContext" connectionString="Offline=False;InitiateOAuth=GETANDREFRESH;" providerName="System.Data.CData.AzureDataCatalog" />
    </connectionStrings>
    <entityFramework>
    <providers>
    ... 
    <provider invariantName="System.Data.CData.AzureDataCatalog" type="System.Data.CData.AzureDataCatalog.AzureDataCatalogProviderServices, System.Data.CData.AzureDataCatalog.Entities.EF6" />
    </providers>
    <entityFramework>
   </configuration>
   </code> 
   

4. Add a reference to System.Data.CData.AzureDataCatalog.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 AzureDataCatalogContext. 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 AzureDataCatalogContext : DbContext {
    public AzureDataCatalogContext() { }
   
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
    // To remove the requests to the Migration History table
    Database.SetInitializer<AzureDataCatalogContext>(null); 
    // To remove the plural names 
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    } 
   }
   

7. Create another .cs file and name it after the Azure Data Catalog entity you are retrieving, for example, Tables. 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("Tables")]
   public class Tables {
    [System.ComponentModel.DataAnnotations.Key] 
    public System.String DslAddressDatabase { get; set; }
    public System.String Type { get; set; }
   }
    
   

8. Now that you have created an entity, add the entity to your context class:

   public DbSet<Tables> Tables { set; get; }
   

9. With the context and entity finished, you are now ready to query the data in a separate class. For example:

   AzureDataCatalogContext context = new AzureDataCatalogContext();
   context.Configuration.UseDatabaseNullSemantics = true;
   var query = from line in context.Tables select line;