如何在mvc5中使用linq to sql连接来显示数据 [英] how to use join in linq to sql in mvc5 to show data

问题描述

错误：附加信息：无法在LINQ to Entities查询中构造实体或复杂类型GHMSaModel.TblGAdrsCity。

Error: Additional information: The entity or complex type 'GHMSaModel.TblGAdrsCity' cannot be constructed in a LINQ to Entities query.

public IEnumerable<TblGAdrsCity> Index()
       {

           IList<TblGAdrsCity> CityList = new List<TblGAdrsCity>();

           var data = (from c in context.TblGAdrsCities
                      join st in context.TblGAdrsStates on c.TblGStateID equals st.StateID
                      join ct in context.TblGAdrsCountries on c.tblGCountryID equals ct.CountryID
                      select c //new TblGAdrsCity{ CityID = c.CityID, CityName = c.CityName,VerifiedStatus=c.VerifiedStatus,CreatedBy=c.CreatedBy,CreatedOn=c.CreatedOn,ActiveStatus=c.ActiveStatus,ModifiedBy=c.ModifiedBy,ModifiedOn=c.ModifiedOn,Remarks=c.Remarks,TblGStateID=st.StateID,tblGCountryID=ct.CountryID}
                      );
           //CityList = data.ToList();
           CityList = data.ToList();
           return (CityList);
       }

推荐答案

狂野猜测：将您的查询转换为ToList（）然后返回。

Wild guess: Convert your query to ToList() and then return.

public IEnumerable<tblgadrscity> Index()
       {
 
           IList<tblgadrscity> CityList = new List<tblgadrscity>();
 
           var data = (from c in context.TblGAdrsCities
                      join st in context.TblGAdrsStates on c.TblGStateID equals st.StateID
                      join ct in context.TblGAdrsCountries on c.tblGCountryID equals ct.CountryID
                      select new TblGAdrsCity{ CityID = c.CityID, CityName = c.CityName,VerifiedStatus=c.VerifiedStatus,CreatedBy=c.CreatedBy,CreatedOn=c.CreatedOn,ActiveStatus=c.ActiveStatus,ModifiedBy=c.ModifiedBy,ModifiedOn=c.ModifiedOn,Remarks=c.Remarks,TblGStateID=st.StateID,tblGCountryID=ct.CountryID}).ToList();
           return (data);
       }</tblgadrscity></tblgadrscity></tblgadrscity>

-KR

-KR

我确实建议阅读这些主题：

该实体不能在LINQ中构建到实体查询 [ ^ ]

e在LINQ to Entities查询中无法构造ntity或复杂类型'[ ^ ]

错误：无法构造实体或复杂类型LINQ to Entities查询 [ ^ ]



答案是：Linq-to-Entities只能投射到匿名类型或普通类（ DTO [ ^ ]）。您无法投影到映射的实体。

I really do suggest to read these threads:
The entity cannot be constructed in a LINQ to Entities query[^]
The entity or complex type ' ' cannot be constructed in a LINQ to Entities query[^]
Error: The entity or complex type cannot be constructed in a LINQ to Entities query[^]

The answer is: Linq-to-Entities can only project to an anonymous type or a regular class(DTO[^]). You can't project onto a mapped entity.

错误：数据中的Count = 0（数据中没有值）











var data =（来自c in context.TblGAdrsCities

在上下文中连接st.TblGAdrsStates在c.TblGStateID上等于st.StateID

加入ct在context.TblGAdrsCountries上c.tblGCountryID等于ct.CountryID

选择新的Customizeview

{

CityID = c.CityID，

CityName = c.CityName，

VerifiedStatus = c.VerifiedStatus，

CreatedBy = c.CreatedBy，

CreatedOn = c.CreatedOn，

ActiveStatus = c.ActiveStatus，

ModifiedBy = c.ModifiedBy，
ModifiedOn = c.ModifiedOn，

备注= c。备注，

StateName = st.StateName，



}）。ToList（）;











返回查看（数据）;

}

Error:Count=0 in data(no value in data )





var data = (from c in context.TblGAdrsCities
join st in context.TblGAdrsStates on c.TblGStateID equals st.StateID
join ct in context.TblGAdrsCountries on c.tblGCountryID equals ct.CountryID
select new Customizeview
{
CityID = c.CityID,
CityName = c.CityName,
VerifiedStatus = c.VerifiedStatus,
CreatedBy = c.CreatedBy,
CreatedOn = c.CreatedOn,
ActiveStatus = c.ActiveStatus,
ModifiedBy = c.ModifiedBy,
ModifiedOn = c.ModifiedOn,
Remarks = c.Remarks,
StateName = st.StateName,

}).ToList();





return View(data);
}

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