如何解决“指定的包含路径无效”？ [英] How Do I Resolve "A specified Include path is not valid"?

问题描述

我有一个相当基本的父子关系设置。最终的结果是，我希望能够通过ASP.NET MVC WebAPI将生成的表返回为JSON。我正在使用Entity Framework 5.0 beta 2.

我可以用一个简单的例子演示我遇到的错误。给出类别类别和产品与相应的数据上下文：

  public class Category 
 {
 public int CategoryId {get;组; } 
 public string标题{get;组; } 
 
 public virtual IEnumerable< Product>产品{get;组; } 
} 
 
 public class Product 
 {
 public int ProductId {get;组; } 
 public string标题{get;组; } 
 
 public virtual Category Category {get;组; } 
 public virtual int CategoryId {get;组; } 
} 
 
 public class ProductDataContext：DbContext 
 {
 public DbSet< Category>分类{get;组; } 
 public DbSet< Product>产品{get;组; } 
} 
  

当我尝试运行包含产品的查询时，我得到以下内容错误：

 指定的包含路径无效。 EntityType'FooAndBar.Category'
不声明具有名称Products的导航属性。 
  

要获取的语句非常简单：

  var everything = dc.Categories 
 .Include（c => c.Products）; 
  

正确的方法是设置列和/或查询，以便产品包含在 Categories ？

解决方案

儿童收藏属性必须被声明为 ICollection< T> ，而不是 IEnumerable< T> 。

此外，您不需要向子类显式添加 CategoryId 字段; EF将在数据库中自动创建。

I have a parent-child relationship setup that is fairly basic. The end result is that I want to be able to return the resulting tables as JSON through ASP.NET MVC WebAPI. I am using Entity Framework 5.0 beta 2.

I can demonstrate the error I'm running into with a simple example. Given the classes Category and Product with the corresponding data context:

public class Category
{
    public int CategoryId { get; set; }
    public string Title { get; set; }

    public virtual IEnumerable<Product> Products { get; set; }
}

public class Product
{
    public int ProductId { get; set; }
    public string Title { get; set; }

    public virtual Category Category { get; set; }
    public virtual int CategoryId { get; set; }
}

public class ProductDataContext : DbContext
{
    public DbSet<Category> Categories { get; set; }
    public DbSet<Product> Products { get; set; }
}

When I try to run a query that includes the products I get the following error:

A specified Include path is not valid. The EntityType 'FooAndBar.Category' 
does not declare a navigation property with the name 'Products'.

The statement to fetch is pretty straightforward:

var everything = dc.Categories
            .Include(c => c.Products);

What is the correct way to setup the columns and/or the query so that the Products are included with the Categories?

解决方案

Child collection properties must be declared as anICollection<T>, not anIEnumerable<T>.

Also, you do not need to explicitly add a CategoryId field to the child class; EF will create that automatically in the database.

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