How to Access Outlook 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 Outlook 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 Outlook Entity Framework 6 assembly and the connection string.

   Using OAuth Authentication

   Microsoft Graph API uses OAuth 2.0 for authentication. You must register an application in the Microsoft Azure Portal to obtain OAuth credentials (Client ID and Client Secret).

   Obtaining OAuth Credentials

   1. Log in to the Azure Portal.
   2. Navigate to Azure Active Directory > App registrations.
   3. Click New registration to create a new application.
   4. Enter an application name and select the appropriate account types.
   5. Set the Redirect URI to your application's callback URL (e.g., http://localhost:33333 for desktop apps).
   6. Click Register to create the application.
   7. On the application overview page, copy the Application (client) ID - this is your OAuthClientId.
   8. Navigate to Certificates & secrets and create a new client secret.
   9. Copy the client secret value - this is your OAuthClientSecret.
   10. Navigate to API permissions and add the required Microsoft Graph API permissions:
       • Mail.Read - For accessing email messages
       • Contacts.Read - For accessing contacts
       • Calendars.Read - For accessing calendar events
       • Tasks.Read - For accessing To Do tasks
       • offline_access - For obtaining refresh tokens
   11. Click Grant admin consent to grant these permissions.

   Connecting with OAuth

   After setting the following connection properties, you are ready to connect:

   • AuthScheme: Set this to OAuth.
   • InitiateOAuth: Set this to GETANDREFRESH. The CData API Profile for Outlook will automatically walk through the OAuth process in order to obtain the access token.
   • OAuthClientId: Set this to the Application (client) ID from Azure Portal.
   • OAuthClientSecret: Set this to the client secret value from Azure Portal.
   • TenantId: Set this to your Azure AD tenant identifier (GUID or domain name like 'contoso.onmicrosoft.com').
   • CallbackURL: Set this to the Redirect URI you specified in your app registration (e.g., http://localhost:33333 for desktop apps).

   Example connection string

   Profile=C:\profiles\Outlook.apip;AuthScheme=OAuth;InitiateOAuth=GETANDREFRESH;OAuthClientId=your_client_id;OAuthClientSecret=your_client_secret;TenantId=your_tenant_id;CallbackUrl=http://localhost:33333;
   

   <configuration>
    ... 
    <connectionStrings>
    <add name="APIContext" connectionString="Offline=False;Profile=C:\profiles\Outlook.apip;AuthScheme=OAuth;InitiateOAuth=GETANDREFRESH;OAuthClientId=your_client_id;OAuthClientSecret=your_client_secret;TenantId=your_tenant_id;CallbackUrl=http://localhost:33333;" providerName="System.Data.CData.API" />
    </connectionStrings>
    <entityFramework>
    <providers>
    ... 
    <provider invariantName="System.Data.CData.API" type="System.Data.CData.API.APIProviderServices, System.Data.CData.API.Entities.EF6" />
    </providers>
    <entityFramework>
   </configuration>
   </code> 
   

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

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

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

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

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

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