LINQ to Entities does not recognize the method 'Int64 ToUnixTime(System.DateTime)' method,and this method cannot be translated into a store expression

关于在LINQ表达式中出现错误，就是方法不能将时间转成表达式，经过不断的思考，终于明白了转码解决。本人就是想把后台的时间对象转成时间戳然后传给前台调用。

这样就出错：

 var comments = CommentSrv.GetListByCondition(t => t.ProductId == id //商品评论

                                 && t.Type ==Type

                                 && t.Content != null

                                && t.Content != " ").OrderByDescending(t => t.CreateDate);
 var product = new {//展示商品的评论内容（包含时间，商品名，评论）
                    data.ID,
                    data.Name,
                    Commnents = comments，
                    CreateDate = t.CreateDate.ToUnixTime()//时间转换
                    };

失败提示：
LINQ to Entities does not recognize the method 'Int64 ToUnixTime(System.DateTime)' method, and this method cannot be
translated into a store expression.

修改后：

var comments = CommentSrv.GetListByCondition(t => t.ProductId == id //商品评论

                                 && t.Type ==Type

                                 && t.Content != null

                                && t.Content != " ").OrderByDescending(t => t.CreateDate)).ToList()；//只要修改这里就可以
 var product = new {//展示商品的评论内容（包含时间，商品名，评论）
                    data.ID,
                    data.Name,
                    Commnents = comments，
                    CreateDate = t.CreateDate.ToUnixTime()//时间转换毫秒
                    };

时间戳转换结果：

"CreateDate":1336755430000