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One of the frequently asked questions is about the lifetime of a DataContext. Should it be a long-lived, application-scoped object or should it be a short-lived, request-scoped object? Let's get to the answer by considering the key parameters: DataContext is ideally suited for a "unit of work" approach : Retrieve a bunch of objects through one or more queries, make changes to the resulting object graph based on user input (databound to controls) or some other request and then call SubmitChanges(). Read More...
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I got a few mails and saw a few forum posts about the confusion created by new locations for dll/exe in beta2. So here is where you can find LINQ to SQL related files. New .NET Framework 3.5 DLLs ( ">green bits ) are in: Program Files\Reference Assemblies\Microsoft\Framework\v3.5\ SqlMetal.exe is in Program Files\Microsoft SDKs\Windows\V6.0A\Bin\ Another source of confusion - designer vs. SqlMetal The visual designer for generating mapped LINQ to SQL classes is a part of Visual Studio 2008. You need Read More...
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Orcas beta2 is here for you. This is significantly ahead of beta1 and pretty close to the final feature set of Orcas for most components. The releases are available both as regular installs and as VPC images . Now that Orcas beta2 has been released, it is time to look at what's new there. But first, a general sense of how beta2 shaped up. Beta1 released in spring was mostly productization of the May 2006 LINQ CTP. So those who played with it only a little bit did not see a big change over May 2006 Read More...
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It has been a while since I posted but given the continuing response and the start of TechEd, it is time to restart. A number of us from the C# team are here: Luca Bolognese , Charlie Calvert , Karen Liu , Luke Hoban and Kathy Lu. Even if you can't join us in Orlando, you can still join us virtually for the talks and even ask questions. We have a great lineup of talks coming up: DEV324 - The .NET Language Integrated Query (LINQ) Framework Tuesday, June 5 8:30 AM - 9:45 AM, N320 A DEV338 - Microsoft Read More...
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With a tip of a hat to Rudyard and his ballad , I would say Oh SQL is SQL and C# is C#, and never the twain shall meet Till rows and objects manually a dev has both to beat But there is neither SQL nor C#, nor join nor dot When LINQ stands to link the twin what magic have I got Ballads aside, this is a real problem that we are grappling with. There is really nothing new about this problem - it is the problem of Object Relational Mapping (ORM). The two worlds are rules by languages and run-times that Read More...
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Let's say you build an app that uses a traditional ORM concept of lazy loading. Your app binds an Order object to a grid and lets the user lazily load related objects like OrderLines. Your user - a normal cubicle dweller, queries for an Order and then decides to go get some coffee. She comes back, navigates to OrderLines and ... Oops! Some data changed in between the time the Order was explicitly queries and the OrderLines were implicitly lazily loaded. Of course, the ORM builders know and understand Read More...
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Good question - in the kitchen of course! The dish is now ready on the LINQ home page and our VP - Soma has a nice blog about it already. I feel exhausted but happy to be able to share the results of "our" work with you. The word "our" in English is strange - it has both inclusive and exclusive meanings. Here, I mean it the truly in inclusive sense - something that belongs to we + you. Not to be too corny but since the last PDC, many of you pushed us where we needed to be pushed. Repeatedly, you Read More...
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OK, the title is buzzwordy and doesn't mean much but here is the question I want to pose as we evaluate the relative priorities of various multi-tier scenarios in DLinq. Do you use the same type on mid-tier and on presentation / web-service client tier? I have seen many discussions about how some people want to use the same assemblies on mid-tier and presentation tier (or even on web-service clients). I personally think that the two should be designed separately and should not be the same unless Read More...
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Currently, when DLinq retrieves entities, it automatically inserts them in an identity cache. This ensures that if you run two queries whose results overlap, you get the same objects by reference - not copies. The object reference after all is the identity in CLR world. This ensures that when you change an entity, you don't need to worry about which copy you are changing - there is only one. So update anomalies can be avoided. This comes at some minimal cost - hashing the object ref and maintaining Read More...
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I got a couple of emails and a question on my blog about chat transcripts. DLinq transcripts may be a bit tricky to find since they are filed under Visual Studio rather than .NET Framework. It takes 2-3 weeks to get the transcripts up so the latest one won't show up for a while. See http://msdn.microsoft.com/chats/transcripts/vstudio/default.aspx for some of the recent C#, VB and DLinq chat transcripts. Read More...
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The DLinq team is looking forward to your questions and comments today at 1pm Pacific Time in this chatroom: http://msdn.microsoft.com/chats/chatroom.aspx The official chat schedule entry . Add a reminder to your calendar . The chatroom itself . All upcoming developer chats . Have some time zone questions ? Read More...
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OK, after hibernating in the winter, I am back on the blog. Some of you joined us on DLinq chat last week so you already have a sense of what is going on. For others, here is a peek at what we are working on: Inheritance: table-per-hierarchy: It turns out that this feature is more interesting in the LINQ context than in a traditional ORM sense (e.g. ObjectSpaces). Languages like C# and VB provide you a variety of ways to work with types and they all show up in DLinq queries. Take for example C# operators Read More...
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We will have our second LINQ and C# 3.0 language chat on Thursday, October 20, 2005 at 1pm Pacific Time (GMT - 8:00). Last time we were overwhelmed with 5x as many questions as usual but hope to do better this time. Overall schedule of MSDN chats is at: http://msdn.microsoft.com/chats/ Read More...
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Here is another FAQ I got about DLinq at PDC. How does DLinq handle changes to objects? How is it similar to or different from ADO.NET DataAdapter? Here is a quick overview of what goes on under the covers at a conceptual level: Before objects are modified: Original values are copied for Detecting changes; and Detecting optimistic concurrency conflicts After SubmitChanges() is called: Modified objects in the object graph are identified. This includes changes in relationships between persistent objects Read More...
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Just over a week ago, we had a Microsoft MVP summit here in Redmond. It was great to meet with such a smart and energized group of people who really get what we do and even better, tell us when we don't get it! Their dedication was really admirable - imagine showing up on Saturday morning at 8:30 am after a Friday night party. We had a series of breakout sessions - each repeated four times to ensure small group discussion. It was a bit exhausting but very rewarding. Here is one thing I had promised Read More...
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