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

   You can authenticate to Linear with a personal API key or with OAuth 2.0. The API key is the simplest option for connecting with your own Linear account.

   Authenticating with an API Key

   Set the following connection properties:

   • AuthScheme: Set this to APIKey.
   • APIKey: A Linear personal API key.

   To create a personal API key, log in to Linear, open Settings > Security & access > Personal API keys, select New API key, and create it. Copy the key immediately, because Linear shows it only once.

   Authenticating with OAuth

   OAuth requires a custom OAuth application registered in Linear (Settings > API > OAuth applications), which provides the OAuthClientId and OAuthClientSecret. Two flows are supported:

   • Authorization code: Set AuthScheme to OAuth, InitiateOAuth to GETANDREFRESH, and provide OAuthClientId, OAuthClientSecret, and the CallbackURL defined in your application (e.g., http://localhost:33333). The driver opens Linear in your browser so you can grant access.
   • Client credentials: Set AuthScheme to OAuthClient and provide OAuthClientId and OAuthClientSecret. This authenticates the application itself, with no browser interaction, and suits machine-to-machine integrations.

   By default, the driver requests the read,write scopes. The driver refreshes the access token automatically when it expires.

   
   
   <configuration>
      ... 
     <connectionStrings>
       <add name="LinearContext" connectionString="Offline=False;AuthScheme=APIKey;APIKey=myAPIKey;" providerName="System.Data.CData.Linear" />
     </connectionStrings>
     <entityFramework>
       <providers>
          ... 
         <provider invariantName="System.Data.CData.Linear" type="System.Data.CData.Linear.LinearProviderServices, System.Data.CData.Linear.Entities.EF6" />
       </providers>
     <entityFramework>
   </configuration>
   </code> 
   

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

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

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

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