CSLA and the Entity Framework

Pretty much everything from L2S applies to EF.  You would use EF in the same way with CSLA as you would L2S – as DAL.  I have been working part-time on CSLA/SL/EF project, and I actually like the combination.  We are not using stored procedures, just plain EF.  The DAL code is very different if you are using L2S with stored procedures though.   You still create a context though, retrieve the entity (for updates, inserts and deletes) and update it from BO, then call SaveChanges on context.  Retrieve data code is pretty much identical to L2S.  I think using EF results in less code than when you are using raw ADO, especially when it comes to parent/child/grandchild object trees.  There is a learning curve (albeit not very steep) in learning how to satisfy relationships during update process.  I think I will be talking at Atlanta Code Camp on CSLA for Silverlight, and I am planning to copy and re-work Rolodex project to use EF.  The Code Camp is in three weeks.  Whether my sessions gets approved or not, I will have the sample working and post all code in any case.

Sergey Barskiy

Principal Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

I have searched all over the internet for a single example of the two technologies (CSLA and EF) can work together but in vain. In theory, EF should provide CSLA with the DAL. In practice, no one seems to have attempted it yet.

Can someone please point me to a good example? And can someone answer me a simple question: what is to be gained from using the two together since it's very obvious that the two can be used independently?

I have looked at Rocky's Expert C# 2008 Business Objects but it dwells more on L2S and just a mention of EF. With rumors going around (and I suspect they are not just rumors) that MS is no longer interested in further development of L2S I would have thought anyone choosing between L2S and EF should have chosen EF. Or what I am I missing?

Not that I am aware of.  Oddly enough, I do a fair amount of hand-coding on business objects, but I did write a small code generator myself.  It does not create entire objects, just code blocks, such as properties, data access code and some validation rules.   This tool allows me to pick fields from multiple tables, then I just copy/paste what I need into my business objects.  I found that this approach is not much slower to me than full code gen, but it results in cleaner code IMHO because I only write methods that I need for each object,  Just my 2 cents though, I know that majority of people cod-gen entire classes.  I will surely post the project in about 3 weeks, give or take.

Sergey Barskiy

Principal Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

Thanks both,

Sergeyb, I had actually tried to play around with EF/CSLA but your advice makes me feel like I am on the right track. Once you are done with your project, please post it somewhere we can access it.

I am trying to take advantage of some of EF's features most notably Table per Type Inheritance. One of the problems I am running into is that most code generation tools can only generate the BO???s from the database schema. This means that although I have all the fields I want in entities, there is no way of generating BO???s from them. I have to create either Views or Stored Procedures with joins to generate my BO???s so that the fields correspond with those of the entities. The other option is writing the BO???s by hand.

Anyone has any ideas how one can go round this?

I used 3.6.2 for this sample.  Make sure you are referencing correct version of CSLA and Silverlight.  I am not sure what else would cause the issue.  Knowing exact error might help…

Sergey Barskiy

Principal Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

I'm just bumping this up ...

Anyone have any ideas on the EF sample?

Chris

I am guessing that default value needs to be explicitly casted.

Sergey Barskiy

Principal Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

Hi Sergey,

Thank you so much for your response.  I apologize for not seeing your reply until now.  I started with 3.6.2, but got a strange error "The call is ambiguous between the following methods or properties" similar to the one described in this post: http://forums.lhotka.net/forums/thread/32337.aspx  So, I assumed I needed to use the earlier 3.6.1 version and that is when I got the XAML error on lines dealing with the csla datagrid validation control.  So, I will upgrade again to using 3.6.2.

So, I should have csla.net 3.6.2 framework and SL2.  I'll try again.  Can you please take a look at the error discussed here http://forums.lhotka.net/forums/thread/32337.aspx?  Any idea what was the cause of the original error "The call is ambiguous between the following methods or properties".  My gut feeling was that the client was using cslalight and the server was using csla.  Since the object class is shared between the client and the server code base the compiler was confused about a particular property.

I'm excited to migrate up to EF from LINQ to SQL and your sample app is the only model I know of to follow.  So, I'm anxious to get it working.

Best regards,

Chris