How Can LINQ Efficiently Update Properties of a Collection in C#?

Optimizing C# Collection Updates with LINQ

LINQ offers efficient methods for modifying properties across a collection of objects. While the ForEach extension method provides a loop-like syntax:

<code class="language-csharp">collection.ForEach(c => c.PropertyToSet = value);</code>

A purely LINQ-based approach achieves the same result:

<code class="language-csharp">collection.Select(c => { c.PropertyToSet = value; return c; }).ToList();</code>

Crucially, ToList() forces immediate execution, overcoming LINQ's inherent lazy evaluation.

Consider a practical example: updating the timestamp of blog comments. To add 10 hours to each comment's DateAdded property within the business layer:

<code class="language-csharp">var comments = _context.Comments.Where(c => c.BlogPostId == blogPostId);

comments.Select(c => { c.DateAdded = c.DateAdded.AddHours(10); return c; }).ToList();

_context.SaveChanges();</code>

This LINQ approach streamlines the update process, eliminating the need for direct SQL manipulation and neatly integrating data modification into your business logic.

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