# Saturday, 13 March 2010

This week Telerik released a new LINQ implementation that is simple to use and produces domain models very fast. Built on top of the enterprise grade OpenAccess ORM, you can connect to any database that OpenAccess can connect to such as: SQL Server, MySQL, Oracle, SQL Azure, VistaDB, etc. While this is a separate LINQ implementation from traditional OpenAccess Entites, you can use the visual designer without ever interacting with OpenAccess, however, you can always hook into the advanced ORM features like caching, fetch plan optimization, etc, if needed.

Just to show off how easy our LINQ implementation is to use, I will walk you through building an OData feed using “Data Services Update for .NET Framework 3.5 SP1”. (Memo to Microsoft: P-L-E-A-S-E hire someone from Apple to name your products.) How easy is it? If you have a fast machine, are skilled with the mouse, and type fast, you can do this in about 60 seconds via three easy steps. (I promise in about 2-3 weeks that you can do this in less then 30 seconds. Stay tuned for that.)

 Step 1 (15-20 seconds): Building your Domain Model

In your web project in Visual Studio, right click on the project and select Add|New Item and select “Telerik OpenAccess Domain Model” as your item template. Give the file a meaningful name as well.


Select your database type (SQL Server, SQL Azure, Oracle, MySQL, VistaDB, etc) and build the connection string. If you already have a Visual Studio connection string already saved, this step is trivial.  Then select your tables, enter a name for your model and click Finish. In this case I connected to Northwind and selected only Customers, Orders, and Order Details.  I named my model NorthwindEntities and will use that in my DataService.


Step 2 (20-25 seconds): Adding and Configuring your Data Service

In your web project in Visual Studio, right click on the project and select Add|New Item and select “ADO .NET Data Service” as your item template and name your service.


In the code behind for your Data Service you have to make three small changes. Add the name of your Telerik Domain Model (entered in Step 1) as the DataService name (shown on line 6 below as NorthwindEntities) and uncomment line 11 and add a “*” to show all entities. Optionally if you want to take advantage of the DataService 3.5 updates, add line 13 (and change IDataServiceConfiguration to DataServiceConfiguration in line 9.)

   1:  using System.Data.Services;
   2:  using System.Data.Services.Common;
   4:  namespace Telerik.RLINQ.Astoria.Web
   5:  {
   6:      public class NorthwindService : DataService<NorthwindEntities>
   7:      {
   8:          //change the IDataServiceConfiguration to DataServiceConfiguration
   9:          public static void InitializeService(DataServiceConfiguration config)
  10:          {
  11:              config.SetEntitySetAccessRule("*", EntitySetRights.All);
  12:              //take advantage of the "Astoria 3.5 Update" features
  13:              config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
  14:          }
  15:      }
  16:  }


Step 3 (~30 seconds): Adding the DataServiceKeys

You now have to tell your data service what are the primary keys of each entity. To do this you have to create a new code file and create a few partial classes. If you type fast, use copy and paste from your first entity,  and use a refactoring productivity tool, you can add these 6-8 lines of code or so in about 30 seconds. This is the most tedious step, but don’t worry, I’ve bribed some of the developers and our next update will eliminate this step completely.

Just create a partial class for each entity you have mapped and add the attribute [DataServiceKey] on top of it along with the key’s field name. If you have any complex properties, you will need to make them a primitive type, as I do in line 15. Create this as a separate file, don’t manipulate the generated data access classes in case you want to regenerate them again later (even thought that would be much faster.)

   1:  using System.Data.Services.Common;
   3:  namespace Telerik.RLINQ.Astoria.Web
   4:  {
   5:      [DataServiceKey("CustomerID")]
   6:      public partial class Customer
   7:      {
   8:      }
  10:      [DataServiceKey("OrderID")]
  11:      public partial class Order
  12:      {
  13:      }
  15:      [DataServiceKey(new string[] { "OrderID", "ProductID" })]
  16:      public partial class OrderDetail
  17:      {
  18:      }
  20:  }


Done! Time to run the service.

Now, let’s run the service! Select the svc file and right click and say “View in Browser.” You will see your OData service and can interact with it in the browser.


Now that you have an OData service set up, you can consume it in one of the many ways that OData is consumed: using LINQ, the Silverlight OData client, Excel PowerPivot, or PhP, etc.

Happy Data Servicing!

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