Using IActionConstraints in ASP.NET Core MVC

net core asp.net core asp.net mvc

ASP.NET Core provides a way to constraint parameter values when matching routes via an IRouteConstraint (read more here) interface. This can be very useful, if you want to disambiguate certain routes from one another. This functionality is built into the routing package and is independent from the MVC framework.

However, aside from that, the MVC framework itself also provides an interesting constraint-mechanism - IActionConstraints. Let’s have a look at them today.

Resolving ASP.NET Core Startup class from the DI container

net core asp.net core c-sharp

In ASP.NET Core, the most common setup is characterized by having a standalone Startup class, responsible for bootstrapping the services needed by your application, as well as setting up the application pipeline.

What most users of ASP.NET Core do not realize, is that at runtime, the Startup instance is actually being resolved from the DI container. This allows you to control some interesting aspects of how your application is bootstrapped, which can be really important i.e. in integration testing scenarios.

Let’s have a look.

Using Roslyn refactorings with OmniSharp and Visual Studio Code

omnisharp visual studio code

One of the features that we added to a recent OmniSharp release (which, as a reminder, backs the C# language services in various editors), and that quietly shipped in C# for Visual Studio Code 1.10.0 last week, was the ability to use external Roslyn refactorings.

Before, OmniSharp shipped with some built-in Roslyn refactorings (i.e. move type to file) but this new feature allows a user to import custom refactorings - either self- or 3rd-party built.

It’s still an experimental feature, so it needs to be switched on manually, but hopefully it can provide you some much neeeded productivity boost.

Let’s have a look at how that’s done.

Running multiple independent ASP.NET Core pipelines side by side in the same application

net core asp.net core asp.net mvc

The other day I started looking into a problem of being able to run several independent ASP.NET Core pipelines from within the same main application, running on top of the same Kestrel server. This was actually asked on MVC Github repo but closed without a real answer.

Let’s have a detailed look at the problem, and (one) possible solution to it.

Disposing resources at the end of ASP.NET Core request

net core asp.net core

Today, let’s have a look at dealing with disposable objects in ASP.NET Core. Imagine you have an object that you’d like to reuse throughout the duration of the HTTP request, but at the end, it must clean up some of its open resources or handles. This is a common requirement for i.e. file writers, DB connections, other unmanaged resources or external processes - to mention just a few.

Building microservices with ASP.NET Core (without MVC)

net core asp.net core

There are several reasons why it makes sense to build super-lightweight HTTP services (or, despite all the baggage the word brings, “microservices”). I do not need to go into all the operational or architectural benefits of such approach to system development, as it has been discussed a lot elsewhere.

It feels natural that when building such HTTP services, it definitely makes sense to keep the footprint of the technology you chose as small as possible, not to mention the size of the codebase you should maintain long term.

In this point I wanted to show a couple of techniques for building very lightweight HTTP services on top ASP.NET Core, without the use of any framework, and with minimal code bloat.

C# code formatting settings in VS Code and OmniSharp

c-sharp omnisharp visual studio code

I quite often get or see questions about configuring C# code formatting settings for Visual Studio Code.

OmniSharp (the open source Roslyn-based technology that powers C# language services) in VS Code exposes a rich set of code formatting settings which you can use to tailor and customize your C# experience.

Let’s have a look at how you can use them.

Accessing HttpContext outside of framework components in ASP.NET Core

net core asp.net core

When developing web applications with ASP.NET, it is common to end up in situations where you require access to HttpContext. This wouldn’t be anything special, but outside of the context of framework level APIs such as controllers, middleware and so on (which would always give you a way to fetch the current HttpContext), it can be tricky.

While generally speaking, HttpContext could be passed around as a regular dependency to the logical components that require it, that solution is often impractical.

Let’s have a look at how you can get a hold of HttpContext in ASP.NET Core.

Writing C# build scripts with FAKE, OmniSharp and VS Code

c-sharp fsharp scripting

In this blog post I’d like to show an extremely - in my opinion - productive way of writing build scripts using C#. As a basis, we’ll use the excellent core FAKE library called FakeLib, which is written F# and consume it in C# scripts.

Sure, there are other projects/task runners like Cake or Bau that allow you to write C# build scripts (few more actually out there) but the approach I’d like to show you today, is I think the most productive of all, so bear with me.

More after the jump.

Announcing ConfigR 1.0

net c-sharp

Recently we released version 1.0 of ConfigR - a popular .NET configuration library, that lets you configure your application via C# scripts (CSX).

This is also the last release requiring full .NET 4.5/Mono - the next version of ConfigR is going to be a netstandard.

Here’s a overview of the features that are there in 1.0!

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Hi! I'm Filip W., a cloud architect from Zürich 🇨🇭. I like Toronto Maple Leafs 🇨🇦, Rancid and quantum computing. Oh, and I love the Lowlands 🏴󠁧󠁢󠁳󠁣󠁴󠁿.

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