public async Task<ActionResult> Manage(ManageUserViewModel model)
        {
            bool hasPassword = HasPassword();
            ViewBag.HasLocalPassword = hasPassword;
            ViewBag.ReturnUrl = Url.Action("Manage");
            if (hasPassword)
            {
                if (ModelState.IsValid)
                {
                    IdentityResult result = await UserManager.ChangePasswordAsync(User.Identity.GetUserId(), model.OldPassword, model.NewPassword);
                    if (result.Succeeded)
                    {
                        return RedirectToAction("Manage", new { Message = ManageMessageId.ChangePasswordSuccess });
                    }
                    else
                    {
                        AddErrors(result);
                    }
                }
            }
            else
            {
                // User does not have a password so remove any validation errors caused by a missing OldPassword field
                ModelState state = ModelState["OldPassword"];
                if (state != null)
                {
                    state.Errors.Clear();
                }

                if (ModelState.IsValid)
                {
                    IdentityResult result = await UserManager.AddPasswordAsync(User.Identity.GetUserId(), model.NewPassword);
                    if (result.Succeeded)
                    {
                        return RedirectToAction("Manage", new { Message = ManageMessageId.SetPasswordSuccess });
                    }
                    else
                    {
                        AddErrors(result);
                    }
                }
            }

            // If we got this far, something failed, redisplay form
            return View(model);
        }
        public async Task<ActionResult> Manage(ManageUserViewModel model)
        {
            bool hasPassword = HasPassword();
            ViewBag.HasLocalPassword = hasPassword;
            ViewBag.ReturnUrl = Url.Action("Manage");
            if (hasPassword)
            {
                if (ModelState.IsValid)
                {
                    IdentityResult result = await UserManager.ChangePasswordAsync(User.Identity.GetUserId(), model.OldPassword, model.NewPassword);
                    if (result.Succeeded)
                    {
                        return RedirectToAction("Manage", new { Message = ManageMessageId.ChangePasswordSuccess });
                    }
                    else
                    {
                        AddErrors(result);
                    }
                }
            }
            else
            {
                // User does not have a password so remove any validation errors caused by a missing OldPassword field
                ModelState state = ModelState["OldPassword"];
                if (state != null)
                {
                    state.Errors.Clear();
                }

                if (ModelState.IsValid)
                {
                    IdentityResult result = await UserManager.AddPasswordAsync(User.Identity.GetUserId(), model.NewPassword);
                    if (result.Succeeded)
                    {
                        return RedirectToAction("Manage", new { Message = ManageMessageId.SetPasswordSuccess });
                    }
                    else
                    {
                        AddErrors(result);
                    }
                }
            }

            // Wurde dieser Punkt erreicht, ist ein Fehler aufgetreten; Formular erneut anzeigen.
            return View(model);
        }