Stating with C# 9.0, you can use the static modifier on lambda functions. For instance, you can write the following code: enumerable.Select(static x => x * 2); When you use the static modifier on a lambda function, the compilers ensures that there is no capture of variables from the enclosing scope. This allows the compiler to generate better code. Indeed, it can cache the lambda function and reuse it… [read more]

There are multiple ways to iterate on a ConcurrentDictionary<TKey, TValue> in .NET. You can use the foreach loop, or the Keys and Values properties. Both methods provide different results, and you should choose the one that best fits your needs. Using the foreach loop The foreach loop lazily iterates over the key-value pairs in the ConcurrentDictionary. This means that the loop will only fetch the next… [read more]

To improve the UX, it can be useful to listen to clipboard changes. For instance, you can fill a 2FA code in a text box when the user copies it to the clipboard. This can be done using the AddClipboardFormatListener function. Here is a simple example of how to listen to clipboard changes in a WPF application: First, you need to add the Microsoft.Windows.CsWin32 package to your project. This package… [read more]

The default keyword is a powerful tool in C#. For reference types, it returns null, and for value types (structs), it returns a zeroed-out value. Interestingly, default(T) and new T() can yield different results for structs (check out for more info). Initially, C# required default(T), but now you can simply use default when the type can be inferred by the compiler. But how does the compiler infer the… [read more]

Entity Framework Core allows to update the database schema using migrations. The migrations are created manually by running a CLI command. It's easy to forget to create a new migration when you change the model. To ensure the migrations are up-to-date, you can write a test that compares the current model with the snapshot model: [Fact] public async Task EnsureMigrationsAreUpToDate() { await using var… [read more]

When using Entity Framework Core, I prefer to view the generated schema as SQL. This allows me to easily validate what EF is doing behind the scenes and ensures that no attributes are missed, such as accidentally using nvarchar(max). My main objectives are: Be notified when the schema changes Review the new schema while editing it and during code reviews The solution I use is use is to have a test that… [read more]

Both MSTest and xUnit are great test framework. If you are curious about, I've written many blog posts about them MSTest series If you want to migrate to xUnit from MSTest, I've written a Roslyn Analyzer. This analyzer reports all MSTest attributes and assertions in your code. It can also replace most of them with xUnit equivalent. Note that the goal of this analyzer is not to handle 100% of the cases,… [read more]

Roslyn Analyzer can be used to detect patterns in your code and report them. It can also provide code fixes to automatically fix the issues. In this case the code fix takes the existing SyntaxTree and return the new SyntaxTree with the issue fixed. Roslyn does provide the concept of Annotation to mark a node in the SyntaxTree. You can use special annotations to indicate Roslyn to post-process the syntax… [read more]

I've written a lot about Roslyn in the context of Roslyn Analyzers and Source Generators. You can also use Roslyn as a library to analyze and generate code. For instance, you can create a console application that loads a solution, find patterns, and rewrite code. While Roslyn Analyzers are tied to a single project, you can use Roslyn as a library to analyze a whole solution. Let's create the console… [read more]

HTTP Strict Transport Security (HSTS) is a security feature that indicates a client to only connect to a website over HTTPS. Websites can set the Strict-Transport-Security header to inform the client to always use HTTPS. ASP.NET Core can easily set the header, but there is no built-in feature to enable HSTS for an HttpClient. In this post, I describe how to create an HttpClient that supports HSTS,… [read more]