实体框架代码第一 - 加载加载不能正常工作？ [英] Entity Framework Code First - Eager Loading not working as expected?

问题描述

我有以下Entity Framework POCO类：

  public class Customer 
 {
 public int Id {get; set;} 
 public string Name {get; set;} 
 
 public virtual ICollection< Order>订单{get; set;} 
} 
 
 public class Order 
 {
 public int Id {get; set;} 
 public int CustomerId {get ; set;} 
 public int OrderTypeId {get; set;} 
 
 public virtual OrderType类型{get; set;} 
 public virtual Customer Customer {get; set;} b $ b} 
 
 public class OrderType 
 {
 public int Id {get; set;} 
 public virtual ICollection< Order>问题是，当我返回我的       code> ICollection< Order> 我得到 Order 好，但 OrderType  Order 的c $ c>属性。我的订单将包含以下详细信息：
  Id：1 
 CustomerId：1 
客户： b $ b OrderTypeId：3 
类型：null //从未返回
  
如下：
  public void ConfigureOrder（ModelBuilder builder）
 {
 //从订单映射 - > Customer 
 builder.Entity< Order>（）
 .HasRequired（x => x.Customer）
 .WithMany（x => x.Orders）
 .HasConstraint （order，cust）=> order.CustomerId == cust.Id）; 
 
 //从订单映射 - > OrderType 
 builder.Entity< Order>（）
 .HasRequired（x => x.OrderType）
 .WithMany（x => x.Orders）
 .HasConstraint （order，type）=> order.OrderTypeId == type.Id）; 
} 
  
 
 
我已经禁用了在我的上下文中的延迟加载：
  public Context（string connectionString）
：base（connectionString）
 {
 ObjectContext.ContextOptions.LazyLoadingEnabled = false ; 
} 
  
为了返回我的仓库中的数据，我使用包含 System.Data.Entity 的方法：
  var query = from item in context.Customers 
 .Include（x => x.Orders）
其中item.Id == customerId 
 select item; 
  
 
 
我假设是因为我不能指定 Orders.OrderType ，这是问题，所以我尝试一些变化：
  1  - .Include（x => x.Orders.FirstOrDefault（）。OrderType）
 2  - > .include（Orders）
 3  - > .Include（Orders）
 .Include（Orders.OrderType）
  
我不能得到要返回的OrderType属性，除非我直接加载Order：
  var query = .Orders 
 .Include（x => x.OrderType）
选择项目; 
  
此代码将在订单中正确返回OrderType。
解决方案
哦亲爱的。看起来我是一头驴子。这是17:45，我现在应该回家了。
 
 
 
我有两个Get方法：
  Get（int customerId）
 {
 //这是我在
内测试的方法var query = from context in context.Customers 
 .Include（Orders.OrderType）
 select item; 
} 
 
 Get（int customerId，int versionId）
 {
 //这是运行
的方法var query = .customers 
 .Include（item.Orders）
 select item; 
} 
  
因此，Orders.OrderType是正确的，虽然看起来很讨厌的解决方案。我需要一些咖啡因。
 
 
 
 编辑： 
 
 
 
 ，include的最好方法是使用 System.Data.Entity 的I​​nclude方法：
  .Include（x => x.Orders.Select（o => o.OrderType））; 
  
 
I have the following Entity Framework POCO classes:
public class Customer
{
    public int Id {get;set;}
    public string Name {get;set;}

    public virtual ICollection<Order> Orders {get;set;}
}

public class Order
{
    public int Id {get;set;} 
    public int CustomerId {get;set;}
    public int OrderTypeId {get;set;}

    public virtual OrderType Type {get;set;}
    public virtual Customer Customer {get;set;}
} 

public class OrderType 
{
    public int Id {get;set;}
    public virtual ICollection<Order> Orders {get;set;}
}
The problem is that when I return my ICollection<Order> I'm getting the Orders alright, but the OrderType property of the Order is not being populated. My Order will contain the following detail:
Id:          1
CustomerId:  1
Customer:    Populated
OrderTypeId: 3
Type:        null        // Never returned
My mapping code looks like the following:
public void ConfigureOrder(ModelBuilder builder)
{
    // Mapping from Order -> Customer
    builder.Entity<Order>()
        .HasRequired(x => x.Customer)
            .WithMany(x => x.Orders)
                .HasConstraint((order, cust) => order.CustomerId == cust.Id);

    // Mapping from Order -> OrderType
    builder.Entity<Order>()
        .HasRequired(x => x.OrderType)
            .WithMany(x => x.Orders)
                .HasConstraint((order, type) => order.OrderTypeId == type.Id);
}
I've then disabled Lazy loading in my context:
public Context(string connectionString)
    : base(connectionString)
{
    ObjectContext.ContextOptions.LazyLoadingEnabled = false;
}
So to return the data in my repository I use the Include method of System.Data.Entity:
var query = from item in context.Customers
                .Include(x=> x.Orders)
            where item.Id == customerId
            select item;
I was assuming that because I couldn't specify Orders.OrderType, that was the problem, so I tried some variations:
1 -> .Include(x=> x.Orders.FirstOrDefault().OrderType)
2 -> .Include("Orders")
3 -> .Include("Orders")
     .Include("Orders.OrderType")
But I can never get the OrderType property to be returned, unless I just load the Order directly:
var query = from item in context.Orders
                .Include(x=> x.OrderType)
            select item;
This code will correctly return the OrderType within the order.
解决方案
Oh dear. Looks like I was a total donkey. It's 17:45, I should of gone home by now anyway.

I had two Get methods:
Get(int customerId)
{
    // This was the method I was testing within
    var query = from item in context.Customers
                    .Include("Orders.OrderType")
                select item;
}

Get(int customerId, int versionId)
{
    // This was the method that was running
    var query = from item in context.Customers
                    .Include(item.Orders)
                select item;
}
So, "Orders.OrderType" was the correct, albeit nasty looking solution. I need some caffeine.

EDIT:

Just coming back to this question, the best way for includes is to use System.Data.Entity's Include method:
.Include(x=> x.Orders.Select(o=> o.OrderType));


                        
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