Registration identity asp.net core code example
Example: asp.net core identity get user id
public async Task<IActionResult> YourMethodName()
{
var userId = User.FindFirstValue(ClaimTypes.NameIdentifier) // will give the user's userId
var userName = User.FindFirstValue(ClaimTypes.Name) // will give the user's userName
ApplicationUser applicationUser = await _userManager.GetUserAsync(User);
string userEmail = applicationUser?.Email; // will give the user's Email
}