Browsing posts in: asp.net core

Overriding externally set headers and HTTP status codes in ASP.NET Core

I was working on an interesting issue in an ASP.NET Core recently. An external framework was responsible for creating an HTTP Response, and I was only in control of a little component that customized some internal behaviours (via a relevant extensibility point), without being able to influence the final response sent over HTTP.

This is common if you think about extending things like CMS systems or specialized services like for example Identity Server. In those situations, more often than not, the framework would be highly opinionated in what it is trying to do at the HTTP boundaries and as a result, trying to override the HTTP status codes or headers it produces may not be easy.

Let’s have a look at a simple generic workaround.

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Controllers as action filters in ASP.NET Core MVC

It is common to leverage action filters when building MVC applications – this was the case in classic ASP.NET MVC, in ASP.NET Web API and is a still widely used technique (with much richer support!) in ASP.NET Core MVC.

What is not commonly known though, is that it’s possible for controllers to act as their own filters – so let’s have a look at this feature today.

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Dependency injection into actions in ASP.NET Core MVC 2.1

A few years ago I blogged about dependency injection directly into actions in ASP.NET Web API. The idea is quite simple – instead of injecting all of your dependencies via the controller’s constructor, you can inject them as parameters into the action handling a given HTTP request.

This can help you prevent over-injection in the constructor; I also like this approach because it’s very verbose and clear – an action explicitly manifests what it needs to handle the request and gets just that, nothing more.

It actually works out of the box in ASP.NET Core, so let’s have a look at that and some related configuration.

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Generic and dynamically generated controllers in ASP.NET Core MVC

One of those recurring themes that seem to come back fairly regularly among .NET web developers, is the usage of generic controllers to define endpoints in their Web APIs. I have witnessed these discussions as part of ASP.NET MVC, then ASP.NET Web API and most recently in ASP.NET Core MVC.

While I don’t necessarily see a huge need or benefit for generic controllers, I can imagine that – especially in enterprise context – there are scenarios where exposing similarly structured, “cookie-cutter” CRUD endpoints quickly and seamlessly, could possibly have some business value.

Let’s have a look at generic controllers then, and how we could also dynamically feed types into them.

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[Required] and [BindRequired] in ASP.NET Core MVC

When controlling the binding behavior of models in ASP.NET Core MVC applications, it is very common to perform some validation on them. For that, data annotations are a perfect tool.

One of the most typical use cases of data annotations is to ensure that a value of a certain property has been provided by the caller of the API – and this, historically (in “classic” ASP.NET MVC), has been controlled by RequiredAttribute. The attribute can still be used in ASP.NET Core MVC, but there is also a new one – BindRequiredAttribute.

Let’s have a look at the subtle differences between them.

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Customizing query string parameter binding in ASP.NET Core MVC

A few years ago I blogged about binding parameters from URI in ASP.NET Web API. One of the examples in that post was how to bind a comma-separated collection passed to your API as a query string parameter.

Technologies change, and we now work with ASP.NET Core (and the MVC Core framework), but problems remain the same – so let’s have a look at how we can customize the way parameters are bound from query string in ASP.NET Core MVC.

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Using MessagePack with ASP.NET Core MVC

Some time ago (actually, almost 5 years ago), I blogged about using MessagePack with ASP.NET Web API in order to improve your API’s efficiency over JSON – both in terms of serialization speed and in message payload size.

That code later made it to the WebApiContrib project, where it was released as an add-on to ASP.NET Web API.

I recently had a thought – since we now have WebApiContrib.Core for ASP.NET Core, why not revisit the idea, and create a MessagePack add-on for that too?

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