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LINQ to Entities不识别方法***,因此该方法无法转换为存储表达式

时间:2014-07-30 11:28:33      阅读:290      评论:0      收藏:0      [点我收藏+]

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我的程序里有这么一段代码:

order.OrderExpressInfo = (from oei in orderExpressRepository.Entities
                                      where oei.OrderId == order.OrderId
                                      select new EbcBuy.Bll.Orders.Models.OrderExpress
                                      {
                                          ContentInfo = oei.ContentInfo,
                                          CreatedTime = oei.CreatedTime,
                                          CreatedUserId = oei.CreatedUserId,
                                          ExpressId = oei.ExpressId,
                                          ExpressName = oei.ExpressName,
                                          ExpressOrderId = oei.ExpressOrderId,
                                          Freight = oei.Freight,
                                          Manifest = oei.Manifest,
                                          OrderId = oei.OrderId,
                                          ReceiverContactInfo = new ContactInfoModel()
                                            {
                                                ZipCode = oei.CustomerZipCode,
                                                Telephone = oei.CustomerPhone,
                                                MobilePhone = oei.CustomerTel,
                                                Address = oei.CustomerAddress,
                                                LinkMan = oei.CustomerReceiverName,
                                                ProvinceId = oei.CustomerArea.ProvinceId,
                                                ProvinceName = oei.CustomerArea.ProvinceName,
                                                CityId = oei.CustomerArea.CityId,
                                                CityName = oei.CustomerArea.CityName,
                                                CountyId = oei.CustomerArea.DistrictId,
                                                CountyName = oei.CustomerArea.DistrictName
                                            },
                                          ShopId = order.OrderId,
                                          ShopName = order.ShopName,
                                          ShopContactInfo = new ContactInfoModel()
                                              {
                                                  ZipCode = oei.ShopZipCode,
                                                  Telephone = oei.ShopTel,
                                                  MobilePhone = oei.ShopPhone,
                                                  Address = oei.ShopAddress,
                                                  LinkMan = oei.ShopLinkMan,
                                                  ProvinceId = oei.ShopArea.ProvinceId,
                                                  ProvinceName = oei.ShopArea.ProvinceName,
                                                  CityId = oei.ShopArea.CityId,
                                                  CityName = oei.ShopArea.CityName,
                                                  CountyId = oei.ShopArea.DistrictId,
                                                  CountyName = oei.ShopArea.DistrictName
                                              }
                                      }).FirstOrDefault();

其中,ContactInfoModel是一个实体类,定义了买家或卖家的contact信息,  实体类 EbcBuy.Bll.Orders.Models.OrderExpress
具备两个该类型的属性, ReceiverContactInfo和ShopContactInfo。 这里使用linq to entity要给这2个属性赋值, 要注意了,这里给ContactInfoModel初始化设置的属性个数和顺序必须相同。 否则,运行时会报如下异常:

“System.NotSupportedException”类型的未经处理的异常在 EntityFramework.dll 中发生

其他信息: 在单个 LINQ to Entities 查询中的两个结构上不兼容的初始化过程中出现类型“EbcBuy.Bll.Common.Models.ContactInfoModel”。类型可以在同一查询中的两个位置初始化,但前提是在这两个位置设置了相同的属性,且这些属性是以相同的顺序设置的。

 

 

我这个ContactInfoModel在项目里好多的linq to entity代码里进行这样的初始化, 为了提高复用,我把上面的初始化封装成了一个方法, 供各处调用。 修改后的代码如下:

 order.OrderExpressInfo = (from oei in orderExpressRepository.Entities
                                      where oei.OrderId == order.OrderId
                                      select new EbcBuy.Bll.Orders.Models.OrderExpress
                                      {
                                          ContentInfo = oei.ContentInfo,
                                          CreatedTime = oei.CreatedTime,
                                          CreatedUserId = oei.CreatedUserId,
                                          ExpressId = oei.ExpressId,
                                          ExpressName = oei.ExpressName,
                                          ExpressOrderId = oei.ExpressOrderId,
                                          Freight = oei.Freight,
                                          Manifest = oei.Manifest,
                                          OrderId = oei.OrderId,
                                          ReceiverContactInfo = GetCustomerContactInfoModelFromPO(oei),
                                          ShopId = order.OrderId,
                                          ShopName = order.ShopName,
                                          ShopContactInfo = GetShopContactInfoModelFromPO(oei)
                                      }).FirstOrDefault();
GetCustomerContactInfoModelFromPOGetShopContactInfoModelFromPO定义很简单,你懂的。
结果,在运行时,文章标题提到的异常出现了:
“System.NotSupportedException”类型的未经处理的异常在 EntityFramework.dll 中发生

其他信息: LINQ to Entities 不识别方法“EbcBuy.Bll.Common.Models.ContactInfoModel GetCustomerContactInfoModelFromPO(EbcBuy.Dal.Orders.Models.OrderInfo)”,因此该方法无法转换为存储表达式。

【园子里搜索了一下, 有如下结论】在LINQ to Entities 中,使用lambada或linq时,变量一定要提前转换好,可不能到lambada里或linq里再转换。如:

var o= _db.Dictionary.Where(x => x.Type.Equals(type4.ToString()));

.ToString必然产生错误,应该:

string t=type4.ToString();

var o= _db.Dictionary.Where(x => x.Type.Equals(t));

用lambada或linq时,不要尝试去转换内置类型,是不允许的,如:

string t=type4.ToString();

var o= _db.Dictionary.Where(x => Convert.ToString(x.Type).Equals(t));

Convert.ToString必然要出错.

可以考虑使用如下方式:

using System.Data.Objects.SqlClient;  //在 System.Data.Entity.dll 中
//获取市级地区
public JsonResult GetCity(string id)
{ 
    var city = from c in db.AreaDivide
    where SqlFunctions.StringConvert((double)c.ParentID) == id
    select new { text = c.AreaName, value = c.ID };

    return Json(city.ToList(), JsonRequestBehavior.AllowGet);
}

 

 

不过,像我这种情况,无法复用的话,还真是谈不上简洁性了。不晓得还有没有什么好的解决办法...

LINQ to Entities不识别方法***,因此该方法无法转换为存储表达式,布布扣,bubuko.com

LINQ to Entities不识别方法***,因此该方法无法转换为存储表达式

标签:style   blog   color   使用   os   strong   io   cti   

原文地址:http://www.cnblogs.com/buguge/p/3877224.html

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