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In LINQ, Don’t Use Count() When You Mean Any()

If you have a list, array, or query in a C#/LINQ application and need to check and see if the list is empty, the correct way to do this is to use the Any() extension method:

if (q.Any())
{

Similarly, you can check to see if any elements in the list meet a certain condition:

if (q.Any(i => i.IsSpecial))
{

If [...]

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join in LINQ to SQL and LINQ to Entities Considered Messy, Redundant

In this post I will demonstrate that use of the join keyword in LINQ to SQL and LINQ to Entities is nearly always wrong. LINQ queries which you write with the join keyword are harder to read and write than queries you write using associations, and they require knowledge of database metadata which is not [...]

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Projecting Onto a Presentation Model with the Entity Framework and ASP.NET MVC

In this post, I will demonstrate how to map entity models to views in an ASP.NET MVC application without worrying about implementation details like eager loading, lazy loading, or having to manually optimize SQL for the task at hand. I will argue that expressing the relationship between an entity model in the presentation model in [...]

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Skip(0) in LINQ and Testing

A couple of weeks ago, I wrote In LINQ, Beware of Skip(0). In that post, I observed that calling Skip(0) on a query result in LINQ, which has no effect on the dataset returned, imposes a performance penalty with at least some LINQ providers. At the time I commented that there might be some desirable [...]

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In LINQ, Beware of Skip(0)

Calling IQueryable<T>.Skip(0) seems like it should be "free." In other words, since it will have no effect on the resulting data, there should be little to no performance cost for calling it. But this is demonstrably not true in LINQ to Entities, and it occurs to me that LINQ providers are not required to optimize [...]

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Using jqGrid with ASP.NET MVC: Understanding LINQ Errors

If you spend enough time with the PagedList class that I’ve been using for paging in the method which supplies data to jqGrid, it’s a near-certainty that sooner or later you will see a LINQ error with Count in the call stack. The error may seem confusing, because it has nothing to do with Count. [...]

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