public IQueryable<UserLogin> GetAll()
{
        return _userRepository.GetAll();
}

public IQueryable<UserLogin> FilterUsers(int? roleId, string userName, bool? enabled)
        {
            Expression<Func<UserLogin, bool>> expression = u =>
                                                           (!roleId.HasValue ||
                                                            u.Roles.Select(r => r.Id).Count(t => t == roleId.Value) > 0)
                                                           && (string.IsNullOrWhiteSpace(userName) ||
                                                               u.UserName.Contains(userName.Trim())) &&
                                                           (!enabled.HasValue || u.Enabled == enabled.Value);

            return GetAll().Where(expression);
        }

return GetAll().Where(u => !enabled.HasValue || u.Enabled == enabled.Value);

public class UserLogin : BaseEntity
    {
        private IList<Role> _roles;

        public UserLogin()
        {
            _roles = new List<Role>();
        }

        public virtual int Id { get; set; }

        /// <summary>
        /// 用户名
        /// </summary>
        public virtual string UserName { get; set; }

        /// <summary>
        /// Email
        /// </summary>
        public virtual string Email { get; set; }

        public virtual string Password { get; set; }

        /// <summary>
        /// 是否禁用
        /// </summary>
        public virtual bool Enabled { get; set; }

        public virtual DateTime CreateTime { get; set; }

        public virtual UserInfo UserInfo { get; set; }

        public virtual IList<Role> Roles
        {
            get { return _roles; }
            set { _roles = value; }
        }
    }