MVC3 LINQ多个INNER JOIN

Question

我试图使用两个INNER JOIN使用

var product = from a in db.Product.Include(a => a.Category).Include(a => a.Model) 
select a; 

return View(product.ToList()); 

如果我写了上面的编码，它的主要错误在返回查看（product.ToList（））;

错误表示'元数据集合中的多个项目与'模型'的标识匹配。

当我试着使用

var product = from a in db.Product.Include(a => a.Category) 
select a; 

调试我可以看到SQL查询作为

{SELECT 
[Extent1].[productId] AS [productId], 
[Extent1].[categoryId] AS [categoryId], 
[Extent1].[modelId] AS [modelId], 
[Extent1].[model] AS [model], 
[Extent1].[displaySize] AS [displaySize], 
[Extent1].[processor] AS [processor], 
[Extent1].[ramSize] AS [ramSize], 
[Extent1].[capacityType] AS [capacityType], 
[Extent1].[capacity] AS [capacity], 
[Extent1].[colour] AS [colour], 
[Extent1].[description] AS [description], 
[Extent1].[price] AS [price], 
[Extent1].[threeDayPrice] AS [threeDayPrice], 
[Extent1].[aWeekPrice] AS [aWeekPrice], 
[Extent1].[twoWeekPrice] AS [twoWeekPrice], 
[Extent1].[aMonthPrice] AS [aMonthPrice], 
[Extent1].[threeMonthPrice] AS [threeMonthPrice], 
[Extent1].[sixMonthPrice] AS [sixMonthPrice], 
[Extent1].[stock] AS [stock], 
[Extent2].[categoryId] AS [categoryId1], 
[Extent2].[name] AS [name] 
FROM [dbo].[Product] AS [Extent1] 
INNER JOIN [dbo].[Category] AS [Extent2] ON [Extent1].[categoryId] = [Extent2].[categoryId] 
ORDER BY [Extent1].[model] ASC} 

我要添加INNER JOIN通过modelId到模型实体的外键。

怎么可能？

谢谢。

--Added型号 -

--Prodruct.cs-- 

public class Product 
{ 
[Key] public int productId { get; set; } 

[Required(ErrorMessage = "Please select category")] 
public int categoryId { get; set; } 

[Required(ErrorMessage = "Please select model")] 
public int modelId { get; set; } 

[DisplayName("Model name")] 
public String model { get; set; } 

public virtual Category Category { get; set; } 
public virtual Model Model { get; set; } 
} 

--Category.cs-- 
public class Category 
{ 
[Key] public int categoryId { get; set; } 
public String name { get; set; } 
} 

--Model.cs-- 
public class Model 
{ 
[Key] public int modelId { get; set; } 
public String name { get; set; } 
} 

--RentalDB.cs-- 
public class rentalDB : DbContext 
{ 
public DbSet<Product> Product { get; set; } 
public DbSet<Model> Model { get; set; } 
public DbSet<Customer> Customer { get; set; } 
public DbSet<Order> Order { get; set; } 
public DbSet<Cart> Cart { get; set; } 
public DbSet<Category> Category { get; set; } 
public DbSet<OrderDetails> OrderDetails { get; set; } 

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); 
} 
} 

Answer 1

在我的测试数据库，我在LinqPad

from a in Products.Include("Categories").Include("Suppliers") select a 

跑了这一点，我得到这个生成的sql：

SELECT 
[Extent1].[ProductID] AS [ProductID], 
[Extent1].[ProductName] AS [ProductName], 
... Lots of stuff ... 
FROM [dbo].[Products] AS [Extent1] 
LEFT OUTER JOIN [dbo].[Categories] AS [Extent2] ON [Extent1].[CategoryID] = [Extent2].[CategoryID] 
LEFT OUTER JOIN [dbo].[Suppliers] AS [Extent3] ON [Extent1].[SupplierID] = [Extent3].[SupplierID] 

在我环境，包含接收lambda表达式没有重载，你可能从某个地方得到它，所以我不知道发生了什么您的包括，请尝试更改您的查询到

var product = from a in db.Product.Include("Category").Include("Model") select a;