How to access JWT User.Claims in class library

Question

I've structured my project using DDD, it looks like this:

| CompanyName.API
  | MyControllerThatRequiresJwtToken << Entry point
| CompanyName.Application
| CompanyName.Data
  | EfCoreContext << I would like to get the claims here
| CompanyName.Domain
| CompanyName.IoC
| CompanyName.Test
| CompanyName.UI

I am using Z.EntityFramework.Plus.Audit.EFCore to audit all data changes. I added it to the CompanyName.Data project as this is where my EF Context lives.

Problem is: all requests in the API require a JWT token. I'd like to set the username of the person sending the request in the Audit object that will be saved into the database, however I don't have access to the HttpContext in my data layer.

What would be the best approach to get this information? Injecting IHttpContextAccessor into the data layer perhaps? It doesn't sound like a good plan to make the data layer "Http dependent".

UPDATE

I am not sure how I'd pass it from the Controller to the context. I believe it would need to be injected somehow.

Snippet of EfCoreContext.cs

public override int SaveChanges()
{
   var audit = new Audit();
   audit.CreatedBy = "JWT Username"; // << I'd need it here

   audit.PreSaveChanges(this);
   var rowAffecteds = base.SaveChanges();
   audit.PostSaveChanges();

   if (audit.Configuration.AutoSavePreAction != null)
   {
      audit.Configuration.AutoSavePreAction(this, audit);
      base.SaveChanges();
   }

   return rowAffecteds;
}

Answer 1

Create an interface called IApplicationUser for instance. Give it readonly properties you need like id, name and what not.

Create an implementation of it

public class ApplicationUser : IApplicationUser
{
   private readonly IHttpContextAccessor httpContextAccessor;

   public ApplicationUser(IHttpContextAccessor httpContextAccessor)
   {
      this.httpConntextAccessor = httpContextAccessor;
   }

   public Guid Id => this.GetUserId();

   public string Name => this.GetUserName();

   private Guid GetUserId()
   {
       var subject = this.httpContextAccessor.HttpContext
                         .User.Identity.Claims
                         .FirstOrDefault(claim => claim.Type == JwtClaimTypes.Subject);

       return Guid.TryParse(subject, out var id) ? id : Guid.Empty;
   }

   private Guid GetUserId()
   {
       return this.httpContextAccessor.HttpContext
                         .User.Identity.Claims
                         .FirstOrDefault(claim => claim.Type == JwtClaimTypes.PreferredUserName);
   }
}

Now register that with your DI-Container. For default MS IOC:

services.AddScoped<IApplicationUser, ApplicationUser>();

Inject IApplicationUser where ever you need and use it to get user-information.

Edit: IHttpContextAccessor must be registered. If it isn't the case, do it like that as well

services.AddScoped<IHttpContextAccessor, HttpContextAccessor>();

Edit 2: Just to clarify. This is not meant to be used in a repository or however you would like to call it. Rethink your logic so you can pass that information to your entity before saving data.