C#•3mo ago

✅ Understanding and working around `this`

I am developing an API that uses .NET 8 Identity. i had it all up and running, but i needed the default endpoints defined in app.MapIdentityApi<IdentityUser>() to work a little differently. i was told in order to get this functionality i needed to re impliment those endpoints. So i dug into the libraries (spesificly IdentityApiEndpointRouteBuilderExtensions.cs in the namespace Microsoft.AspNetCore.Routing), found MapIdentityApi, and coppied it into Program.cs. So far so good. ive coppied in a bunch of other code and ive got it all working... Except... the signiture:

 public static IEndpointConventionBuilder MapIdentityApi<TUser>(this IEndpointRouteBuilder endpoints)
        where TUser : class, new(){

 public static IEndpointConventionBuilder MapIdentityApi<TUser>(this IEndpointRouteBuilder endpoints)
        where TUser : class, new(){

I have no idea what to do about this IEndpointRouteBuilder endpoints. What does the this keyword do? how can i simulate the functionality of the endpoints parameter? Is this a lost cause? Why don't libraries have comments?

11 Replies

jcotton42•3mo ago

The this modifier makes it an extension method

jcotton42•3mo ago

https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/extension-methods

Extension Methods - C#

Extension methods in C# enable you to add methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type.