Slide Decks and Demos from LINQ to SQL Session at Developer Academy 2

Slide Decks and Demos from LINQ to SQL Session at Developer Academy 2

I gave a session about LINQ to SQL in the Developer Academy 2 conference. From the feedback I got, it seems that the audience had good time and went away with valuable knowledge about LINQ to SQL. I personally had a great time and was very excited all day long.

You can find the slide decks and demos from the session in my presentations page.

If you have any feedback about the session, I'd like to hear it!

Enjoy!

עוזב את אדוונטק

LINQ to SQL Concurrency - ChangeConflictException Row not found or changed

LINQ to SQL Concurrency - ChangeConflictException Row not found or changed

If we create a small model of the Northwind database, and we try to modify one of the customers (lets take ALFKI for example):

We will see that the update command that is created by the run time is:

Of course, the update command updates the City column in the Customers table according to the appropriate CustomerID value, but what with all these other conditions in the where clause?

LINQ to SQL uses Optimistic Concurrency strategy. When it selects records, it does not perform any locking on the selected rows. Only when it tries to update records in the database or delete them, it checks that the records were not changed since the last time they were selected. How does it do it? It tries to update the row that matches the original values, as the DataContext got them when it selected the rows. This explains the additional conditions on the update command.

If during the time the logic was done, updates were made from another program (or another DataContext for that matter), an exception will be thrown:

System.Data.Linq.ChangeConflictException was unhandled
  Message="Row not found or changed."
  Source="System.Data.Linq" 

LINQ to SQL tried to look for the record to updated comparing all the columns to their original values, and when no records where found, the exception was thrown. This is the way LINQ to SQL tells us that the row it was looking for was deleted or changed by another program and the update cannot be done.

Enjoy!

לוח הזמנים של הרצאות הכנס עלה לאויר

Copy Source As Html (CopySourceAsHtml) for Visual Studio 2008 RTM

Copy Source As Html (CopySourceAsHtml) for Visual Studio 2008 RTM

After the release of Visual Studio 2008 RTM, I really needed to blogs about technical stuff and needed Copy Source As Html (CopySourceAsHtml) with Visual Studio 2008 support.

You can download this zip file, and extract it to your Visual Studio 2008 Addins folder. For vista is it C:\Users\<username>\Documents\Visual Studio 2008\Addins, and it should be somewhere under C:\Documents and settings If you're working with XP. Notice that this folder might not be exist, so you should create it.

After placing the files in this directory, simply restart Visual Studio 2008, and you can start working with the addin.

To make things faster, I usually customizing a keyboard shourtcut for this addin. I go to Tools -> Options, and under Environment node I select the Keyboad node. I look for the CopySourceAsHtml.Connect.CopyNow command, and assign Ctrl+Shift+H for it.

Disclaimer: Using the above addin is under the copyrights of J.T. Leigh & Associates Inc. Any use of this addin is not supported and on your own risk.

Copy Source As Html (CopySourceAsHtml) for Visual Studio 2008 RTM.

Enjoy!

LINQ to SQL: Table<T>.Detach Method Does Not Exist

LINQ to SQL: Table<T>.Detach Method Does Not Exist

Moving from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM, I read about LINQ to SQL Breaking Changes from Visual Studio 2008 Beta 2 to RTM.

From the document:

Table<T>.Attach changed to throw an exception if attached entity has not been detached

The designed purpose of Table<T>.Attach method is to let you make a DataContext aware of objects that are transferred from other tiers, usually through serialization/deserialization. Once the entities are attached, the DataContext can track their original state for update purposes as if they had been fetched initially by this DataContext. However, if you attempt to attach an entity from a second DataContext on the same machine without first calling .Detach on that entity, you may start to run into various issues, including deferred loaders that are still set up to load their objects from the original DataContext.

To help reduce this confusion in RTM, we’ve added a check in .Attach to ensure that the entity you’re attaching has been properly detached from its previous DataContext first if it has deferred loaders. We also more intelligently handle related entities linked to by the attached entity to ensure they do not get inserted into the table again if you later attach them as well.

Workaround

Be sure to call Table<T>.Detach on your entities on their original DataContext before trying to call Table<T>.Attach within their new DataContext.

For example, if you write the following code:

You'll get an exception: "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext.  This is not supported."

Whilw trying to follow the above workaround from the document, I realized that Table<T>.Detach method does not exist at all! I even opened Reflector to see it clearly and it is true. Table<T>.Detach method does not exist at all!

Trying to find an answer to the question how can I detach entities that were attached to one DataContext in order to attach to another one, and found this answer in Dinesh Kulkarni's post:

"what do I call to detach an entity? The answer is nothing! If an entity is serialized and deserialized back, it is already detached from the DataContext instance used for retrieval "

Conclusion:

1. There is a bug in the Breaking Changes document. I hope it will be fixed ASAP.

2. You cannot detach the entities from previous DataContext's without serializing and deserializing the entities.

LINQ to SQL Breaking Changes from Visual Studio 2008 Beta 2 to RTM

LINQ to SQL Breaking Changes from Visual Studio 2008 Beta 2 to RTM

With the release of Visual Studio 2008, there are some changes moving LINQ to SQL projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM.

There was already writen by Dinesh Kulkarni, the PM of LINQ to SQL in this post, but now they are officially published in a complete document.

Download it here.

Enjoy!

C# 3.0, LINQ and LINQ to SQL Hands on Labs for Visual Studio 2008 RTM

C# 3.0, LINQ and LINQ to SQL Hands on Labs for Visual Studio 2008 RTM

After the release of Visual Studio 2008 RTM, the Visual Studio 2008 Samples page on MSDN was update accordingly. You can find few Hands on Labs there that will help you practice the new language features:

Additionally, you can Download Visual Studio 2008 and .NET Framework 3.5 Training Kit for other new technologies around.

Enjoy!

Visual Studio 2008 RTM Live and Kicking!

Visual Studio 2008 RTM Live and Kicking!

Yesterday, after the announcement that Visual Studio 2008 RTM Is Available for MSDN Subscribers, I downloaded and installed it, following Scott Guthrie's Installation Suggestions. The installation ran over the night so I can't really tell how long it took, but as of this morning - Visual Studio 2008 RTM Live and Kicking!

Enjoy!

Download Visual Studio 2008 and .NET Framework 3.5 Training Kit

Download Visual Studio 2008 and .NET Framework 3.5 Training Kit

With the release of Visual Studio 2008 RTM earlier today, the Visual Studio 2008 and .NET Framework 3.5 Training Kit is also available for download. (120Mb of training materiel...)

This kit contains Labs, Demos and PPTs about various technologies coming up with Visual Studio 2008 and .Net Framework 3.5. So If you're a little behind, this is your chance to catch up!

Fundamentals: Framework and Language Enhancements

• Lap around Visual Studio 2008 & .NET Framework 3.5
• .NET Language Integrated Query (LINQ)
• Using LINQ with Relational Data
• What's new in C# 3.0?
• What's new in Visual Basic 9.0?
• .NET Framework 3.5 Enhancements
• ADO Synchornization Services

Building Rich Client Experiences

• Introduction to the Microsoft Client Continuum
• Introduction to ASP.NET AJAX
• Building Web Applications with Visual Studio 2008
• Introduction to Silverlight
• What's New in Windows Presentation Foundation 3.5
• Building Windows Presentation Foundation Applications in Visual Studio 2008 and Expression Blend

Building Connected Applications

• Connected Application Foundations using WCF, WF, and Windows CardSpace
• Web Programming with WCF
• Building Microsoft Windows Workflow Foundation Enabled Windows Communication Foundation Services in .NET Framework 3.5
• Integrating Windows CardSpace

Building Applications for Microsoft Office and Windows Mobile

• Overview of Office Business Applications and VSTO
• Extending the Office Fluent UI using VSTO
• Building SharePoint Workflows
• Building Mobile Applications using Visual Studio 2008 and the .NET Compact Framework 3.5

Application Lifecycle Management

• Introducing Application Lifecycle Management
• Value-up software development
• The Business Analyst Perspective
• The Project Managers Perspective
• The Architect Perspective
• The Developers Perspective
• The Testers Perspective

 With this training kit, the teams also posted some sessions on channel 9:

• Lap around Visual Studio 2008 & .NET Framework 3.5 presented by James Conard
• What's new in C# 3.0?  presented by Luke Hoban
• What's new in Visual Basic 9.0? presented by Amanda Silver
• .NET Framework 3.5 Enhancements presented by Jack Gudenkauf
• .NET Language Integrated Query (LINQ) presented by Luca Bolognese
• Using LINQ with Relational Data  presented by Mike Pizzo
• ADO Synchronization Services presented by Steve Lasker

Enjoy!

Visual Studio 2008 RTM Is Available for MSDN Subscribers

Visual Studio 2008 RTM Is Available for MSDN Subscribers

The well anticipated release of Visual Studio 2008 RTM is finally available for download for MSDN Subscribers.

If you're an MSDN Subscriber, go to http://msdn2.microsoft.com/subscriptions and start download Visual Studio 2008 RTM.

Enjoy!

פרטים נוספים לגבי Developer Academy 2

ההרשמה ל- Developer Academy 2 נפתחה

Just Released: Service Factory Modeling Edition (v3) for Visual Studio 2005

Just Released: Service Factory Modeling Edition (v3) for Visual Studio 2005

As I've written in my post Web Service Software Factory Modeling Edition Roadmap, the final release of Service Factory: Modeling Edition (v3) supports Visual Studio 2005 only. The Visual Studio 2008 release should be out around February, the same time that Visual Studio 2008 is launched.

You can download the Service Factory Modeling Edition (v3) for Visual Studio 2005 release from codeplex.

Watch the 15 minutes Walktrough

This walkthrough provides a very brief introduction to people who either do not have a lot of time for an introduction, or those who are looking for a presentation demo.

Download the Hands-On-Labs

This hands-on lab provides eight exercises to briefly introduce most of the experiences of building a Web service using the Service Factory. This includes modeling the services, data contracts, and host options, creating the project structure, and generating the code for both WCF and ASMX implementations. It also shows how to translates from business entities to messages as well as expose and consume the service.

Watch the videos

• Don demonstrates how to create model elements by importing an existing WSDL document. Watch it now (Length: 5:50 - Size: 6.18 MB)
• Don shows off the new project mapping capability for code generation. Watch it now (Length: 7:10 - Size: 11.12 MB)
• Don shows off the very first community release of Service Factory v3. Watch and download it now (Length: 12:41 - Size: 11.4 MB)
• Don introduces the WCF Service Factory. Interested in re-delivering this presentation? Watch and download it now
• Don creates some service interfaces with the WCF Service Factory. Interested in performing this demo yourself? Watch and download it now
• Don introduces a number of ways we think about Web services. Do you agree? Watch it now (Length: 6:01 - Size: 1.97 MB)
• Don and Dragos walk through the Web service domain model the team is working with. Watch it now (Length: 05:14 - Size: 1.41 MB)

If you have any questions about Service Factory Modeling Edition (v3) for Visual Studio 2005, refer to the discussions forum, also on codeplex.

Enjoy!

Frequently Asked Questions and Answers about ADO.Net Entity Framework

Frequently Asked Questions and Answers about ADO.Net Entity Framework

The ADO.Net Entity Framework team has posted the first draft of Entity Framework FAQ. This is a collection of frequently asked questions and answers about ADO.Net Entity Framework, taken from the related MSDN Forum and customers feedback. This is valuable resource for everyone who adapts ADO.Net Entity Framework these days.

Topics you can find there:

• Resources for learning about ADO.Net Entity Framework
• Architecture / Patterns
• POCO Support
• Code Generation
• Databinding
• etc.

Note that this is the first draft, so things may be more descriptive than they will be when this document is done. Additionally, you may offer questions and answers you think that should be there.

Enjoy!