Making ASP.NET Core 3 web API return REST compliant Http return codes

To make an ASP.NET Web Api (core 3+) return valid Http status codes such as 200 OK, 400 Bad request and 404 Not found, use the IActionResult as return type.

Return code 422 can be used instead of 400, read more here: HTTP Status Codes For Invalid Data: 400 vs. 422

Code example C# web API controller “data” endpoint method:

/// <summary>
/// Get data from API
/// </summary>
/// <remarks>
/// GET: api/v1/data?id={id}
/// </remarks>
/// <returns><see cref="IActionResult"/> <see cref="Data"/>Data model</returns>
/// <response code="200">Serialized <see cref="Data"/></response>
/// <response code="400">Invalid id</response>
/// <response code="404">Found no match for id</response>
[ProducesResponseType(typeof(Data), 200)]
[ProducesResponseType(typeof(object), 400)]
[ProducesResponseType(typeof(object), 404)]
public IActionResult GetData(string id)
    var data = business.GetData(id);
    if (data == null)
        return NotFound(null); //404 not found
    if (data.IsValid)
        return Ok(data); //200 OK, found
        return BadRequest(data.ValidationErrorMessage); //400 bad reqeust validationerror

IActionResult type

The IActionResult return type is appropriate when multiple ActionResult return types are possible in an action. The ActionResult types represent various HTTP status codes. Any non-abstract class deriving from ActionResult qualifies as a valid return type. Some common return types in this category are BadRequestResult (400), NotFoundResult (404), and OkObjectResult (200). Alternatively, convenience methods in the ControllerBase class can be used to return ActionResult types from an action. For example, return BadRequest(); is a shorthand form of return new BadRequestResult();.

Because there are multiple return types and paths in this type of action, liberal use of the [ProducesResponseType] attribute is necessary. This attribute produces more descriptive response details for web API help pages generated by tools like Swagger[ProducesResponseType] indicates the known types and HTTP status codes to be returned by the action.

More info:
Controller action return types in ASP.NET Core web API | Microsoft Docs
HTTP Status Codes For Invalid Data: 400 vs. 422

ASP.NET Core 2.2 preview – Updated routing handling

We’re making a big investment in routing starting in 2.2 to make it interoperate more seamlessly with middleware. For 2.2 this will start with us making a few changes to the routing model, and adding some minor features. In 3.0 the plan is to introduce a model where routing and middleware operate together naturally. This post will focus on the 2.2 improvements, we’ll discuss 3.0 a bit further in the future.

Source: ASP.NET Core 2.2.0-preview1: Endpoint Routing | ASP.NET Blog

Architect modern web applications with ASP.NET Core and Azure | Microsoft Docs

.NET Core and ASP.NET Core offer several advantages over traditional .NET development. You should use .NET Core for your server applications if some or all of the following are important to your application’s success:

  • Cross-platform support

  • Use of microservices
  • Use of Docker containers
  • High performance and scalability requirements
  • Side-by-side versioning of .NET versions by application on the same server


Online: Architect modern web applications with ASP.NET Core and Azure | Microsoft Docs

Choose between .NET Core and .NET Framework for server apps | Microsoft Docs

There are two supported implementations for building server-side applications with .NET: .NET Framework and .NET Core. Both share many of the same components and you can share code across the two. However, there are fundamental differences between the two and your choice depends on what you want to accomplish. This article provides guidance on when to use each.

Source: Choose between .NET Core and .NET Framework for server apps | Microsoft Docs

Force to run tests serially

Force to run tests in test projects serially; (for integration or ui type of tests)
Add this to the xunit test project app.config file:

<?xml version="1.0" encoding="utf-8" ?>
<add key="xunit.methodDisplay" value="method" />
<add key="xunit.parallelizeAssembly" value="false" />
<add key="xunit.parallelizeTestCollections" value="false" />
<add key="xunit.maxParallelThreads" value="1" />

docs: (.NET) (.NET core)



.NET Core Overview Crash Course (on Linux – but applicable on other systems)

With .NET being open source, you can also install and use the .NET Framework on your Linux machine with multiple languages, such as C#, F#, and Visual Basic (coming soon). This Refcard guides you through productively using .NET on Linux, from installation to debugging. You will find an architectural overview, tips for using the new Command Line Interface (CLI), and tools and helpful settings as they relate to your development efforts. This Refcard also covers building MVC web sites, RESTful services, and standalone applications.

Source: .NET on Linux – DZone – Refcardz