The using statement can be a little bit dangerous at times ...

If you are using Visual Studio 2008 for a project, but are still using an old TFS and an old build server (which is quite likely at the moment), you should prepare for at least some inconveniences.

Genome has been developed with Team Foundation Server (TFS) for some time now, and it might be interesting to know in this context that TechTalk is a Visual Studio Inner Circle partner. TFS has proven to be a good source control system, but there are a few points that could do with a bit of improvement (particularly when compared to Subversion (SVN), with which I have extensive experience; that said, there are some features that both systems lack).

As I am writing this, I am just heading home from TechEd, waiting at the Barcelona airport for my return flight to Vienna. It has been a busy time for the Genome team since September - unfortunately so busy that we couldn’t take time to blog about all the things that are going on. We weren't at TechEd only as attendees, but also exhibiting in the Visual Studio Partner area, with a total of 8 TechTalkers in Barcelona. To catch up with all the things that have happened since September, I’ll start with TechEd, while the memories are still fresh.

Typically, Genome is used to map tables to their data domain objects. But what to do when you have to use a database that is not made for mapping objects and therefore is not in any normalization form etc.?

While documenting/testing Genome 3.3 I stumbled about this strange behaviour, which seems to be a bug of the C# 3.0 beta 2 compiler.

I was trying to compile the following GROUP BY example with Genome:

var ordersPerCountryPerYear1 = from o in Helper.DB.Extent()
                               group o by new { o.Customer.Address.Country, o.OrderDate.Value.Year } into g
                               select new
                               {
                                 Country = g.Key.Country,
                                 Year = g.Key.Year,
                                 OrderCount = g.Count()
                               };

And received the following error from the compiler:

error CS1061: 'System.Linq.IGrouping' does not contain a definition for 'Count' and no extension method 'Count' accepting a first argument of type 'System.Linq.IGrouping' could be found (are you missing a using directive or an assembly reference?)

However, my team insisted that the extension method Count() is provided by Genome. To find out, why the compiler does not find it, they asked me to call it directly in Main():

TechTalk.Genome.Extensions.Linq.InternalIGroupingExtensions.Count(null);

After inserting this call in my code, the program suddenly compiled (including the statement, the C# compiler complained about previously).

We think this is a bug of the compiler. As a workaround I now have the following method on one class in my project to satisfy the compiler :

static void ThisIsNeverCalled()
{
  TechTalk.Genome.Extensions.Linq.InternalIGroupingExtensions.Count(null);
}

Posted by Chris

Technorati Tags: linq

There are a lot of discussions how to properly mock an O/RM to achieve unit testing.

In this article, I will describe how an application implemented with Genome can be tested by means of unit testing. By stealing (and also modifying) the sample domain from Fowler, I’ll demonstrate this with a simple WebShop application. The use case that we are going to investigate is the ordering process itself.

The sample code used is provided for download at the end of the article. You need Genome 3.3 (beta 1) to execute the sample.

TheServerSide.Net has just published our case study about DataReturn's experiences of using Genome to rebuild website for BMW USA. The site has quite critical performance requiremens of up to 1 million sessions per day.

Posted by Chris

Technorati Tags: object relational

Recently we received a question from a customer about how to express a sort criteria based on a condition. As the sort expression in Genome is nothing else than an implicit function (lambda) executed on the candidate element to return the value to sort by, this can be quite easily achieved.

As a simple example, let’s use the Northwind database again. A customer there has a Country and a Region property. Imagine you want to order all customers in the USA by Region and all the other customers by Country. Additionally you want to have USA customers first, then the others.

A Genome set can be sorted using the OrderBy() method. It takes an implicit function as a parameter, which is denoted using [] in OQL. The condition can be expressed using the ? operator, which is translated to a CASE WHEN in SQL. Hence, the order function can be expressed like this:

When the customer is located in the USA, then order by region; otherwise, order by country:

Country=="USA" ? Region : Country

To make sure customers located in the USA are listed first, I am prefixing the Region with a space (I know this is a hack, but it will do for this example). Hence, the final OQL looks like this:

extentof(Customer).OrderBy( [ Country == "USA" ? " " + Region : Country])

which translates to the following SQL:

SELECT … FROM Customers
  ORDER BY
    CASE WHEN (Country="USA")
       THEN (" " + Region)
       ELSE (Country)
    END ASC

Posted by Chris

Technorati Tags: object relational, getting started

The Genome OQL Query Analyzer (QA) is a very helpful tool when you are developing with Genome: it allows you to load a mapped business layer to execute any kind of OQL queries. In this article, I demonstrate how the latest mapped business layer, along with its mapping, can be loaded by starting the Genome QA with a single click in Visual Studio’s solution explorer.