Good post. Looking forward to hearing more about linq to sql in the future.

When you’re in the LINQ to SQL designer and you select a property in an object, one of the options in the Properties window is “Time Stamp” (true/false). If you drag a table onto the designer and the column is of type timestamp, it will set this flag automatically for you.

You can name the column whatever you want, that has no bearing on anything.

i’ve posted about inclusing Linq-to-Sql in N-Tier Applications,
and found interesting the way you described the problem

here is my article about it:
http://blog.pampanotes.com/2008/02/first-thoughts-on-designing-linq.html

This two feature requires customization of the auto-generated code, and the good news are, that creating a custom code-generator isn’t as hard as it looks.

We’re working on a code generator for dbml’s, and we will probably publish it (open sourced) when it’s more polished. By now, If you want we can share some implementation details.

Regards,

You’ve been kicked (a good thing) - Trackback from DotNetKicks.com…

I like this! It works well, except in the scenario (like I got stuck in!) where the database table has INSERT/UPDATE triggers that test for certain columns being modified, and acting upon those changes. A trivial example:

IF UPDATE (LastName)
BEGIN
— Do some logic based on this change
END

In the case of the UPDATE statement generated above, it always causes the LastName column to appear UPDATED. If I could have changed this logic, I would have, but I inherited a badly-built database…

And discusses lifetime management here:
http://www.west-wind.net/WebLog/posts/246222.aspx

I added this post to a list of LINQ to SQL tutorials @ http://rocksthoughts.com/blog/archive/2008/02/23/linq-to-sql-tutorials-articles-and-opinions.aspx

While I love LINQ to SQL some of the ways they implemented features in the first version are a little inefficient like you stated in your post referring to the update.

I wrote a post about something similar here: http://rocksthoughts.com/blog/archive/2008/02/19/linq-to-sql-v-1-0-hickups.aspx

As promised, we published a custom code generator tool, that allows you to keep the O/R Designer GUI, but replace the code generation to allow truly POCOs, a disconnected N-tier change tracking (or even your own custom code generation), we published under GPL here:
http://www.codeplex.com/ULinqGen

And I published some details about our implementation of disconnected change tracking in this post:
http://pampanotes.tercerplaneta.com/2008/03/implementing-n-tier-change-tracking.html

It would be really interesting sharing some comments on this.

Regards,

I’ve tried the steps you described here to save a disconnected LinqToSql entity, but when I try to attach the disconnected entity to a new DataContext instance I get the following 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.

Here’s the code I’ve used to do this:

LinqTestDataContext dc2 = new LinqTestDataContext();

dc2.Companies.Attach(company, true);

dc2.SubmitChanges();

Note that I’ve loaded the company entity using a different datacontext instance and I’ve also added a TimeStamp field on it.

Regards

Interesting post about Linq to SQL. I thought I’ll let you know about my product that actually can work in a disconnected environment and also allows you to do inserts/updates including complete control over what fields are included in such operations. There are lot of other features that allow the developer to create high performance applications very quickly and easily.

For example, if you have an “OrderItems”, an “Orders” object and a “Customers” object, the Quick Objects framework doesn’t make 3 calls to database, it can do it in one and you still can decide what fields should be selected. Same control over concurrency, you are not forced to perform concurrency check on the entire object and you can choose what fields should be used for concurrency check (if you want - very easily).

Honestly, it is the only ORM/framework with this kind of flexibility and control. Best of all it is very light weight and has a code generation built in so a developer is ready to code in just a few minutes.

Well, you can see it at www.quickobjects.com and if you like to review it please let me know and I can get you a complimentary copy ;)

Thanks,
Ish

Quick Objects = Fastest Way To Powerful Applications

The TimeStamp to String and Back Methods can be found here….http://geekswithblogs.net/AndrewSiemer/archive/2008/02/11/converting-a-system.data.linq.binary-or-timestamp-to-a-string-and-back.aspx

What kind of web services are you using? We’re using LINQ to SQL with WCF web services and it has no problem with the timestamps.

Trying to do an update over web services isn’t trivial. The biggest challenge is dealing with entities that have properties that return lists (EntitySet) because you don’t want to pass the entire list back when you want to save the entity when you didn’t change anything in the EntitySet. You also have to deal with re-attaching entities to the DataContext using the Attach() method, which also has some issues that you have to deal with.

I’ve been meaning to write a post about these things, but I’ve been having trouble finding time to write. :) Check back later and maybe I’ll write something up.

Jon

We have no released a Community Edition of Quick Objects which is free for commercial or non-commercial uses. The best thing is that the free version can be used in WCF. It truly is very easy to use and the client application can either use proxy class or reuse the business objects. Take a look at couple of WCF videos on our website to see it for yourself.

Good luck,
Ish

Please have a look and post your valuable comments / suggestions there.