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A few weeks ago, Torsten Grabs – a colleague on the StreamInsight team and accomplished violist – came to me with a potential bug. He was seeing an ADO.NET SqlClient exception when running a StreamInsight query: “ There is already an open DataReader associated with this Command which must be closed first...

A colleague was asking how to construct a particular LINQ “operator macro” today. Basically, he was finding it inconvenient to repeat boilerplate for particular operator patterns in his code, but was struggling to inline expression snippets into LINQ query expressions. Thought I’d share a sample macro...

Over the past couple of weeks, a handful of people have asked for help dynamically creating StreamInsight queries. I usually scrawl some boxes and arrows on the whiteboard and say “you could try something like this…” My hand-waving hasn’t been very helpful. I’ll write some...

I talked a little bit about patterns using InvocationExpression in a previous post (you might want to review the post for some context). It turns out my advice wasn’t that easy to implement… Fortunately, the EFExtensions helper library now includes an ExpandInvocations method that implements the same...

The EFExtensions helper library has a few updates: - CreateCommand now respects the CommandTimeout property on ObjectContext . A user of the library reported this bug to me a while ago, and I’m finally getting around to fixing it. - One tricky scenario involves multiple stored procedure result...

A beta of Visual Studio 2008 SP1 was released on Monday and the ADO.NET Entity Framework (EF) is now in the box! You can download and install the Beta here . The EF Extensions library has been updated to work with the beta and includes several public and internal changes. Source code is available at...

Someone asked a great question on the ADO.NET Entity Framework forums yesterday: how do I compose predicates in LINQ to Entities? I’ll give three answers to the question. Answer 1: Chaining query operators Basically, you have some query and you have some predicates you want to apply to that query...

This week at DevConnections in Orlando, I gave a “deep-dive” talk on LINQ. I wanted to give people a feel for what's possible with the new language features and core APIs in .NET 3.5. I spent most of the talk discussing a single example: take an ADO.NET 2.0 code sample and simplify. Instead of using...