Is there a way to add claims in an ASP.NET Core middleware after Authentication?

Question

I have this in my startup:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperE         


        

Answer 1

You could write your own middleware to add new claims.

public class YourCustomMiddleware
{
    private readonly RequestDelegate _next;

    public YourCustomMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext httpContext)
    {
        if (httpContext.User != null && httpContext.User.Identity.IsAuthenticated)
        {

            httpContext.User.Identities.FirstOrDefault().AddClaim(new Claim("your claim", "your field"));
        }
        await _next(httpContext);
    }
}

and in your app startup

app.UseAuthentication();
app.UseMiddleware();