EF4我如何转换匿名类型的强类型的LINQ

Question

的LINQ代码返回一个匿名类型我怎么能返回一个强类型的“客户”的？ 我正在返回一个匿名类型，因为我只想从实体中选择某些字段。

var customer = from c in _entities.Customers 
          join con 
          in _entities.Contracts on c.CustomerID equals con.customerID 
          where con.contractNo == number 
          select new 
          { 
           Surname = c.Surname, 
           Forename= c.Forename, 
           Address = c.Address, 
           Suburb = c.Suburb, 
           State = c.State, 
           Postcode = c.PostCode, 
           PhoneNo = c.PhoneNo 
         }; 

感谢

Answer 1

要么做

var customer = from c in _entities.Customers 
         join con 
         in _entities.Contracts on c.CustomerID equals con.customerID 
         where con.contractNo == number 
         select c; 

选择客户的情况下，以原样或

Customer customer = (from c in _entities.Customers 
         join con 
         in _entities.Contracts on c.CustomerID equals con.customerID 
         where con.contractNo == number 
         select new Customer{ 
          Surname = c.Surname, 
          Forename= c.Forename, 
          Address = c.Address, 
          Suburb = c.Suburb, 
          State = c.State, 
          Postcode = c.PostCode, 
          PhoneNo = c.PhoneNo 
         }).FirstOrDefault(); 

创建具有只是你的属性客户的新实例有兴趣填写。 （提供的客户类有一个参数的构造函数）

Answer 2

看起来你正在寻找有一个contractNo匹配number任何合同的所有客户 - 不使用连接，而是使用EF导航属性：

var customers = _entities.Customers 
         .Where(c => c.Contracts.Any(x => x.contractNo == number)); 

如果只是单一（或可能没有），这些客户使用SingleOrDefault()只检索单个Customer实体：

Customer customer = _entities.Customers 
          .Where(c => c.Contracts.Any(x => x.contractNo == number)) 
          .SingleOrDefault();