public ActionResult QuitMembership(UserGroup userGroup, UserGroupMembership userGroupMembership, User currentUser) { Require.NotNull(userGroup, "userGroup"); Require.NotNull(userGroupMembership, "userGroupMembership"); Require.IsTrue(() => userGroupMembership.UserGroup.Equals(userGroup), "userGroupMembership"); Require.IsFalse(() => userGroupMembership.MembershipType == UserGroupMembershipType.Quit, "userGroupMembership"); if (!ModelState.IsValid) { return(QuitMembershipForm(userGroup, userGroupMembership, currentUser)); } UserGroupService.QuitOrRemoveMemberships(new[] { userGroupMembership }, currentUser); return(RedirectToAction("AllMemberships", "UserGroup")); }