public CustomersController(
            UserManager <IdentityUser> userManager,
            SignInManager <IdentityUser> signInManager,
            IdentityDbContext identity,
            InherentInvoiceContext context)

        {
            this.userManager   = userManager;
            this.signInManager = signInManager;
            this.identity      = identity;
            this.context       = context;
        }
        public InvoiceController(
            UserManager <IdentityUser> userManager,
            SignInManager <IdentityUser> signInManager,
            IdentityDbContext identity,
            InherentInvoiceContext context,
            IHostingEnvironment hostingEnvironment)

        {
            this.userManager   = userManager;
            this.signInManager = signInManager;
            this.identity      = identity;
            this.context       = context;
        }