CTP4加入表为什么不起作用？ [英] CTP4 Join Table why doesn't work ?
问题描述
使用Northwind数据库，我想建立Employee和Territory的映射，我的鳕鱼在下面。
With Northwind database, I want establish the mapping for Employee and Territory, my cods is below.
模型
班级员工
{
{
    public int ID {get;组; }
public int ID { get; set; }
    public string LastName {get;组; }
public string LastName { get; set; }
&NBSP; &NBSP; public virtual ICollection< Territories>领土{得到;组; }
public virtual ICollection<Territories> Territories { get; set; }
&NBSP; &NBSP; public Employee（）
public Employee ( )
&NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; Territories = new List< Territories> （）;
Territories = new List<Territories> ( );
&NBSP; &NBSP; }
}
}
}
类别地区
class Territories
{
{
&NBSP; &NBSP; public int ID {get;组; }
public int ID { get; set; }
&NBSP; &NBSP; public string Description {get;组; }
public string Description { get; set; }
&NBSP; &NBSP; public virtual ICollection< Employee>员工{get;组; }
public virtual ICollection<Employee> Employees { get; set; }
}
}
配置
类EmployeeConfiguration：EntityConfiguration< Employee>
class EmployeeConfiguration : EntityConfiguration<Employee>
&NBSP; {&NBSP;&NBSP; &NBSP; &NBSP;
{
&NBSP; &NBSP; public EmployeeConfiguration（）
public EmployeeConfiguration ( )
&NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; HasKey（x => x.ID）;
HasKey ( x => x.ID );
&NBSP; &NBSP; &NBSP; &NBSP; HasMany（x => x.Territories）
HasMany ( x => x.Territories )
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; .WithMany（x => x.Employees）
.WithMany ( x => x.Employees )
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; .MAP（QUOT; EmployeeTerritories" ;,（E，T）=>新建
.Map ( "EmployeeTerritories", ( e, t ) => new
&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; {
{
EmployeeID = e.ID，
EmployeeID = e.ID,
;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;的TerritoryID = t.ID
TerritoryID = t.ID
&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP ; }）;
} );
&NBSP; &NBSP; &NBSP; &NBSP; MapSingleType（x => new
MapSingleType ( x => new
{
{
&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;雇员= x.ID，
EmployeeID = x.ID,
&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;名字= x.LastName
LastName = x.LastName
}）
} )
&NBSP; &NBSP; &NBSP; &NBSP; .ToTable（" Employees"）;
.ToTable ( "Employees" );
&NBSP; &NBSP; }
}
}
}
类TerritoriesConfiguration：EntityConfiguration< Territories>
class TerritoriesConfiguration : EntityConfiguration<Territories>
{
{
&NBSP; &NBSP; public TerritoriesConfiguration（）
public TerritoriesConfiguration ( )
&NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; HasKey（x => x.ID）;
HasKey ( x => x.ID );
&NBSP; &NBSP; &NBSP; &NBSP; MapSingleType（x => new
MapSingleType ( x => new
{
{
TerritoryID = x.ID，
TerritoryID = x.ID,
TerritoryDescription = x.Description，
TerritoryDescription = x.Description,
}）
} )
&NBSP; &NBSP; &NBSP; &NBSP; .ToTable（" Territories"）;
.ToTable ( "Territories" );
&NBSP; &NBSP; }
}
}
}
背景
class MyContext：ObjectContext
class MyContext : ObjectContext
{
{
&NBSP; &NBSP; ///< summary>
/// <summary>
&NBSP; &NBSP; /// MyContext的构造函数。
/// Constructor of MyContext.
&NBSP; &NBSP; ///< / summary>
/// </summary>
&NBSP; &NBSP; public MyContext（EntityConnection连接）
public MyContext ( EntityConnection connection )
&NBSP; &NBSP; &NBSP; &NBSP; ：基础（连接）
: base ( connection )
&NBSP; &NBSP; {
{
&NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP;对象集<员工> mEmployees;
ObjectSet<Employee> mEmployees;
&NBSP; &NBSP; public ObjectSet< Employee>员工
public ObjectSet<Employee> Employees
&NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; 获取
get
&NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; if（mEmployees == null）
if ( mEmployees == null )
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; mEmployees = CreateObjectSet< Employee> （）;
mEmployees = CreateObjectSet<Employee> ( );
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; 返回mEmployees;
return mEmployees;
&NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP;对象集<领土> mTerritories;
ObjectSet<Territories> mTerritories;
&NBSP; &NBSP; public ObjectSet< Territories>地区
public ObjectSet<Territories> Territories
&NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; 获取
get
&NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; if（mTerritories == null）
if ( mTerritories == null )
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; mTerritories = CreateObjectSet< Territories> （）;
mTerritories = CreateObjectSet<Territories> ( );
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; 返回mTerritories;
return mTerritories;
&NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; }
}
测试代码
var builder = new ModelBuilder（）;
var builder = new ModelBuilder ( );
&NBSP;&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; builder.Configurations.Add（new EmployeeConfiguration（））;
builder.Configurations.Add ( new EmployeeConfiguration ( ) );
&NBSP; &NBSP; &NBSP; &NBSP; builder.Configurations.Add（new TerritoriesConfiguration（））;
builder.Configurations.Add ( new TerritoriesConfiguration ( ) );
&NBSP; &NBSP; &NBSP; &NBSP; var model = builder.CreateModel（）;
var model = builder.CreateModel ( );
&NBSP; &NBSP; &NBSP; &NBSP; var connection = new SqlConnection（ConfigurationManager.ConnectionStrings [" MyContext"] .ConnectionString）;
var connection = new SqlConnection ( ConfigurationManager.ConnectionStrings [ "MyContext" ].ConnectionString );
&NBSP; &NBSP; &NBSP; &NBSP; using（MyContext context = model.CreateObjectContext< MyContext>（connection））
using ( MyContext context = model.CreateObjectContext<MyContext> ( connection ) )
&NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; foreach（var context in context.Employees）
foreach ( var employee in context.Employees )
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; {
{
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; Debug.WriteLine（employee.LastName）;
Debug.WriteLine ( employee.LastName );
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; foreach（employee.Territories中的var项目）//此处，employee.Territories 的计数为0，为什么？
foreach ( var item in employee.Territories ) // Here the count of employee.Territories is 0 , why?
&NBSP;&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; {
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; Debug.Write（" "）;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; Debug.WriteLine（item.ID）;
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; }
&NBSP; &NBSP; &NBSP; &NBSP; &NBSP; &NBSP; }
}
&NBSP; &NBSP; &NBSP; &NBSP; }
}
使用这些代码，我可以正确检索员工，但我无法检索到employee.Territories，任何人都可以告诉我为什么以及如何解决它？非常感谢。
With these codes, I can retrieve employee correctly, but I can't retrieve employee.Territories, anybody can tell me why and how to solve it? Thanks a lot.
推荐答案
我有一个类似的问题，它没有加载我的父引用对象。
I have a similar problem where it does not load my parent reference object.
不确定问题在哪里。 ..？
Not sure where is the issue. ..?
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