Category Archives: LINQ

Queue is Always Empty Using yield return

Posted on May 4, 2011 by Chris Missal

I ran into an issue in a C# application the other day. Thankfully I figured out what was going wrong right away, but it could have turned into a big headache potentially.

Also posted in ASP.NET MVC | 2 Comments

Autoprojecting LINQ queries

Posted on February 9, 2011 by Jimmy Bogard

Something I’ve been looking at adding to AutoMapper was the idea of doing automatic query projection in the Select query projection in LINQ statements.  One downside of AutoMapper is that projection from domain objects still forces the entire domain object … Continue reading →

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What is Projection?

Posted on March 3, 2010 by Chris Missal

I think there’s great benefit in not only knowing how to design your code to use common patterns but also to be able to speak about them clearly and concisely to others. If I mention that the problem sounds like … Continue reading →

Also posted in Communication, Reading Code | 10 Comments

Implementing Domain Queries

Posted on January 30, 2010 by John Teague

My current Repository interface looks something like this: public interface IRepository { T FindOne<T>(int id); T FindBy<T>(Expression<Func<T, bool>> expression); IEnumerable<T> FindAllBy<T>(Expression<Func<T, bool>> expression); IEnumerable<T> FindAll<T>(); T FindOneBy<T>(Expression<Func<T, bool>> expression); void Save<T>(T target); void Update<T>(T target); void SaveOrUpdate<T>(T target); void Delete<T>(T … Continue reading →

Also posted in Communication, Reading Code | 10 Comments

Selecting Static Results with Dynamic LINQ

Posted on January 23, 2010 by Keith Dahlby

Dynamic LINQ (DLINQ) is a LINQ extension provided in the VS 2008 Samples. Scott Guthrie provides a good overview here: Dynamic LINQ (Part 1: Using the LINQ Dynamic Query Library), but the executive summary is that it implements certain query … Continue reading →

Also posted in Best Practices, Design Principles, Legacy Code, Testing | 8 Comments

LINQ query operators and null lists

Posted on December 8, 2009 by Jimmy Bogard

One of my pet peeves with the LINQ extension methods is their inability to handle null source lists.  For example, this will throw an ArgumentNullException: [Test] public void Should_handle_nulls() { List<int> ints = null; ints.Any(num => num < 0).ShouldBeFalse(); } … Continue reading →

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More missing LINQ operators

Posted on October 16, 2009 by Jimmy Bogard

Continuing an old post on missing LINQ operators, the wonders of extension methods allow us as developers to fill potential holes in LINQ operators.  Whether it’s a Zip method (now included in .NET 4.0), or better methods for IComparer-based operators, … Continue reading →

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Hacking LINQ Expressions: Join With Comparer

Posted on September 19, 2009 by Keith Dahlby

In this installment of my Hacking LINQ series we’ll take a look at providing an IEqualityComparer for use in a LINQ join clause. The Problem Many of the Standard Query Operators require comparing sequence elements and the default query providers … Continue reading →

Also posted in For Fun, Testing | 6 Comments

Hacking LINQ Expressions: Select With Index

Posted on September 15, 2009 by Keith Dahlby

First, a point of clarification: I use LINQ Expressions to mean (Language-INtegrated) Query Expressions (the language feature) rather than Expression Trees (the .NET 3.5 library in System.Linq.Expressions). So what do I mean by “Hacking LINQ Expressions”? Quite simply, I’m not … Continue reading →

Also posted in Favorites | 1 Comment

Simplifying LazyLinq

Posted on September 13, 2009 by Keith Dahlby

This is the fourth in a series of posts on LazyLinq, a wrapper to support lazy initialization and deferred disposal of a LINQ query context: Introducing LazyLinq: Overview Introducing LazyLinq: Internals Introducing LazyLinq: Queryability Simplifying LazyLinq Introducing LazyLinq: Lazy DataContext … Continue reading →

Also posted in Testing | 3 Comments