c＃COM对象问题 [英] c# COM Objects issue

问题描述

背景

Background

我正在C＃上使用Visual Studio 2010交易ActiveX API。由于它是一个ActiveX API，我只是添加了ActiveX作为我的参考。 api提供了三组事情：你可以用来调用API的方法，API为你更新信息的事件以及一些所谓的ActiveX COM对象。

I am working on a trading ActiveX API in visual studio 2010 on C#. Since it is an ActiveX API, I simply added the ActiveX as my reference. The api provides three group of things: Method you could use to call API, the Event with which the API updates information for you and some socalled ActiveX COM object.

ISSUE

ISSUE

这里： C＃boolean int conversion issue 最后，在查看异常被抛出后，我知道这是关于铸造。以下是异常的描述：

I asked a related question here: C# boolean int conversion issue Finally, after viewing the exception has been thrown, I know that it is about casting. Here is the description of exception:

*System.InvalidCastException was unhandled Message=Unable to cast object of type  
InteractiveBrokersTradingSystem.Forex' to type 'TWSLib.IContract'.

*

外汇类：

namespace InteractiveBrokersTradingSystem
{
  class Forex:TWSLib.IContract
  {


    public int conId { get; set; }
    public string symbol { get; set; }
    public string secType { get; set; }
    public string expiry { get; set; }
    public double strike { get; set; }
    public string right { get; set; }
    public string multiplier { get; set; }
    public string exchange { get; set; }
    public string primaryExchange { get; set; }
    public string currency { get; set; }
    public string localSymbol { get; set; }
    public int includeExpired { get; set; }
    public object comboLegs { get; set; }
    public object underComp { get; set; }
    public string comboLegsDescrip { get;set; }
    public string secIdType { get; set; }
    public string secId { get; set; }

    public Forex(string preCurrency,string baseCurrency)
    {
        //conId = 0;
        //symbol = preCurrency;
        //secType = "CASH";
        //expiry = null;
        //strike = double.Parse("0");
        //right = null;
        //multiplier = null;
        //exchange = "IDEALPRO";
        //primaryExchange = "IDEALPRO";
        //currency = baseCurrency;
        //localSymbol = null;
        //includeExpired = 0;
       // comboLegs = null;
        //underComp = null;
        //comboLegsDescrip = null;
        //secType = null;
        //secId = null;


      }
   }
 }

你可以看到，我没有赋予类的属性的任何值，并且异常总是相同的，无论什么类型的值，我分配或不赋值或null。

You could see that I did not assign any value to the properties of the class and the exception is always the same no matter what kind of value I assign or not assign or null.

在下面的api的描述中，我们可以看到一些属性带有（）像strike（）作为doulble，一些不带有（）像secType作为字符串;有人告诉我，这可能是问题。请给我任何与此COM投射问题相关的提示：

In the description of the api below as image we can see that some property with () like strike() as doulble and some not with () like secType as string; someone told me that it might be problem. Please, give me any hint related to this COM casting issue:

推荐答案

你能发布一些实际上失败的代码吗？

Can you post some code that actually fails?

我想发生的是你试图一个COM对象到一个纯.NET类型，并且不工作，因为COM对象需要通过运行时调用包装器或手动映射显式地映射到.NET类型。

I think what's happening is that you're trying to cast a COM object to a plain .NET type and that will not work because the COM object needs to explicitly be mapped to a .NET type either by the Runtime Callable Wrapper or by manual mapping.

一个建议是，跳过显式转换并使用.NET 4.0中的动态类型来访问COM对象的属性，然后将它映射到您需要的任何属性/对象。这样，您就可以准确地看到对象的哪个部分不想映射。

One suggestion I would have is to skip explicit casting and use the dynamic type in .NET 4.0 to access the properties of your COM object, then map it to whatever properties/objects you need it to. That way you'll be able to see exactly which part of the object doesn't want to map.

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