Question

我想填充下面的实体模型：

public class MyModel
{
    public Abc Abc { get; set; }
    public Def Def { get; set; }        
    public List<Ghi> Ghi { get; set; }
}

public class Abc
{
    [Key]
    public int ID { get; set; }
    public string SomeString { get; set; }
}

public class Def
{
    [Key]
    public int ID { get; set; } 
    public string OtherString { get; set; }
}

public class Ghi
{
    [Key]
    public int ID { get; set; }
    public int DefID { get; set; }
    public string ThirdString { get; set; }
}

使用EF＆amp; amp;一些原始SQL查询：

using (var ctx = new ApplicationDbContext())
{
    var abc = ctx.Database.SqlQuery<Abc>(@"SELECT Abc.* FROM XY INNER JOIN Abc ON XY.AbcID = Abc.ID").ToList();
    var def = ctx.Database.SqlQuery<Def>(@"SELECT Def.* FROM XY INNER JOIN Def ON XY.DefID = Def.ID").ToList();
    var ghi = ctx.Database.SqlQuery<Ghi>(@"SELECT Ghi.* FROM XY INNER JOIN Def ON XY.DefID = Def.ID INNER JOIN Ghi ON Def.ID = Ghi.DefID").ToList();
}

但我不能这样做：

var myModel = new MyModel();
myModel.Abc = abc;
myModel.Def = Def;
myModel.Ghi = Ghi;

因为它会给我带来诸如

之类的错误

无法隐式转换类型 'System.Collections.Generic.List'到 'MyProject.Models.Abc'

所以，问题是：

1）如何使用原始SQL将List转换为模型或更好地直接填充模型而不是List？

2）我知道LinQ可以用更少的代码来简化事情......我怎么能用LinQ做呢？

Answer 1

你的错误是自我解释的，你应该这样写：

var myModel = new MyModel();
myModel.Abc = abc.FirstOrDefault();
myModel.Def = Def.FirstOrDefault();
myModel.Ghi = Ghi;

您尝试将带有.ToList()扩展方法的集合放到定义为单个模型的属性中。

Answer 2

尝试代码：

var myModel = new MyModel();
using (var ctx = new ApplicationDbContext())
{
  myModel.ABC= (from p in ctx.XYZ
               join q in ctx.Abc on p.AbcId equals q.Id
               select q).FirstOrDefault();
 var result= (from p in ctx.XYZ
               join q in ctx.Def on p.DefId equals q.Id
               select q).ToList();
 myModel.DEF=result.FirstOrDefault();
 myModel.GHI=( from p in result
                join q in ctx.Ghi on p.Id equals q.DefId
                select q).ToList();

}

如何使用EF原始SQL查询和/或LinQ填充实体模型？

2 个答案: