未找到 Linq-to-Entities Include 方法

发布于 2024-10-21 07:47:34 字数 364 浏览 2 评论 0原文

我在 MVC3 应用程序中使用 EF4，并且正在寻找一种方法来查看给定工作组中的所有联系人。在我指定的控制器中：

var wg = from w in _repo.Workgroups.Include("Contact").ToList();

但出现以下错误：

“System.Linq.IQueryable”不包含“Include”的定义，并且找不到接受“System.Linq.IQueryable”类型的第一个参数的扩展方法“Include”（您是否缺少 using 指令或程序集参考？）

我虽然这个方法内置于 EF4 中。我是否以某种方式启用了它？

原文

I am using EF4 within a MVC3 application and I was looking for a way to view all my contacts within a given workgroup. In the controller I specified:

var wg = from w in _repo.Workgroups.Include("Contact").ToList();

but I get the following error:

'System.Linq.IQueryable' does not contain a definition for 'Include' and no extension method 'Include' accepting a first argument of type 'System.Linq.IQueryable' could be found (are you missing a using directive or an assembly reference?)

I though this method was built into EF4. Do I have enable it somehow?

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伏妖词 2024-10-28 07:47:34

我也遇到了这个错误，并通过添加以下参考解决了它：

using System.Data.Entity;

I was also getting this error and resolved it by adding the following reference:

using System.Data.Entity;

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说谎友 2024-10-28 07:47:34

是的，该方法内置于 EF 中，但在 IQueryable 接口上不可用。它可以在 ObjectQuery 上使用。如果您想在 IQueryable 上调用它，您必须创建自己的扩展，它将当前查询转换为 ObjectQuery 并执行 Include。例如：

public static IQueryable<T> Include<T>(this IQueryable<T> query, string property)
{
  var objectQuery = query as ObjectQuery<T>;
  if (objectQuery == null)
  {
    throw new NotSupportedException("Include can be called only on ObjectQuery");
  }

  return objectQuery.Include(property);
}

或者您必须使用实体框架功能 CTP5，此类扩展已可用。

Yes the method is build into EF but it is not available on IQueryable interface. It is available on ObjectQuery. If you want to call it on IQueryable you must create your own extension wich will convert current query to ObjectQuery and perform Include. Something like:

public static IQueryable<T> Include<T>(this IQueryable<T> query, string property)
{
  var objectQuery = query as ObjectQuery<T>;
  if (objectQuery == null)
  {
    throw new NotSupportedException("Include can be called only on ObjectQuery");
  }

  return objectQuery.Include(property);
}

Or you must use Entity Framework Feature CTP5 where such extensions are already available.

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