Simplify LINQ expression

Applies to: yesVisual Studio noVisual Studio for Mac noVisual Studio Code

This refactoring applies to:

  • C#

What: Refactors instances of SomeEnumerableType.Where(<LambdaExpression>).Single() to SomeEnumerable.Single(<LambdaExpression>) for Enumerable.Single() as well as the following Enumerable methods: SingleOrDefault(), Last(), LastOrDefault(), Any(), Count(), First(), and FirstOrDefault().

When: All instances where the method calls Single(), SingleOrDefault(), and so on, doesn't have any arguments and is preceded by a Where() expression. The input to the Where() expression cannot be constructed as an expression tree.

Why: Removing the unnecessary call to the Enumerable for the .Where() method improves readability and in some cases performance, see remarks.

How-to

  1. Place your cursor within the SomeEnumerableType.Where(<LambdaExpression>).Single() instance in visual studio.

  2. Press Ctrl+. to trigger the Quick Actions and Refactorings menu.

  3. Select Simplify LINQ expression

    Convert typeof to nameof

Remarks

In some cases this refactoring may reduce performance. LINQ operations on List<T> and T[] are not optimized in this case and result in worse performance.

See also