实体框架 - 无法将拉姆达EX pression键入'串'，因为它不是一个委托类型 [英] Entity Framework - Cannot convert lambda expression to type 'string' because it is not a delegate type

问题描述

我使用实体框架在我的基于C＃的code。我遇到了一个意想不到的怪事，我期待的建议。

I am using Entity Framework in my C# based code. I am running into an unexpected weirdness and am looking for suggestions.

案例1，2，3，4 ... 项目：
RivWorks.dll
RivWorks.Service.dll
RivWorks.Alpha.dll

Case 1, 2, 3, 4... Projects:
RivWorks.dll
RivWorks.Service.dll
RivWorks.Alpha.dll

样品（所有这些工作）：
RivWorks.Alpha.dll：

Samples (all of these work):
RivWorks.Alpha.dll:

public static bool EndNegotitation(long ProductID)
{
    var product = (from a in _dbFeed.AutoWithImage 
                   where a.AutoID == ProductID select a).FirstOrDefault();
...
}

RivWorks.Service.dll

public static RivWorks.Model.NegotiationAutos.AutoWithImage 
    GetProductById(long productId)
{
    var myProduct = from a in _dbFeed.AutoWithImage 
                    where a.AutoID == productId select a;

    return myProduct.FirstOrDefault();
}
public static List<RivWorks.Model.NegotiationAutos.AutoWithImage> 
    GetProductByCompany(Guid companyId)
{
    var myProduct = from a in _dbFeed.AutoWithImage 
                    where a.CompanyID == companyId select a;

    return myProduct.ToList();
}

等

案怪事：
RivWorks.Web.Service.dll（WCF项目）
含有作为其他项目中的相同的参考

Case "weirdness":
RivWorks.Web.Service.dll (WCF project)
Contains the same references as the other projects.

public NegotiateSetup GetSetup(string method, string jsonInput)
{
    ...
    long.TryParse(ProductID, out result);
    var product = (from a in _dbFeed.AutoWithImage 
                   where a.AutoID == result select a).FirstOrDefault();
    ...
}

我收到此编译时错误（何处在我的编辑强调这个词）：
无法将拉姆达EX pression键入'串'，因为它不是一个委托类型的

I am getting this compile time error (the word "where" is highlighted in my editor):
Cannot convert lambda expression to type 'string' because it is not a delegate type

任何想法什么会导致此？

Any ideas what would cause this?

推荐答案

对于那些有兴趣的结果：
我是缺少一个简单的使用声明在我的code头。

For those interested in the outcome:
I was missing a simple Using statement at the head of my code.

using System.Linq;

这固定它的权利了。

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