How do you implement versioning in a .NET Core Web API?

API versioning is an important feature in any Web API. It allows clients to make requests to different versions of the API, and it also allows for the gradual rollout of new features.

In .NET Core, you can implement API versioning using the Microsoft.AspNetCore.Mvc.Versioning NuGet package. Here's how you can implement API versioning in your .NET Core Web API:

1. Install the Microsoft.AspNetCore.Mvc.Versioning NuGet package

Install-Package Microsoft.AspNetCore.Mvc.Versioning 

2. In the Startup.cs file, add the following code to the ConfigureServices method:

services.AddApiVersioning(options =>
{
    options.DefaultApiVersion = new ApiVersion(1, 0);
    options.AssumeDefaultVersionWhenUnspecified = true;
    options.ReportApiVersions = true;
});



This code sets the default API version to 1.0, assumes the default version when it is not specified in the request, and reports the available API versions in the response.

3. In the Startup.cs file, add the following code to the Configure method:

app.UseApiVersioning();


This code adds API versioning middleware to the request pipeline.

4. In the controllers where you want to use versioning, add the [ApiVersion] attribute to the class or method:

[ApiController]
[ApiVersion("1.0")]
[Route("api/v{version:apiVersion}/[controller]")]
public class MyController : ControllerBase
{
    // ...
}
 


This code sets the version number for the controller to 1.0 and adds the version number to the route.

Now, you can use the Accept-Version header or the version query parameter in the request to specify the API version you want to use. For example, to use version 1.0 of the MyController, you can make a request to /api/v1.0/mycontroller.

This is a simple way to implement API versioning in your .NET Core Web API.