“类型不匹配"；从COM +(VBScript)访问ref返回的数组时出错 [英] "Type Mismatch" error when accessing array returned by ref from COM+ (VBScript)

问题描述

我有一个正在作为COM +服务器组件运行的.NET 3.5程序集，我想从VBScript(经典ASP页面)中调用此类中的方法.

I have a .NET 3.5 assembly which is being run as a COM+ server component, and I want to call a method in this class from VBScript (a Classic ASP page).

这是方法概述；

public bool FillArray(ref string[] arrayToFill)
{
    ...
}

我的VBScript如下；

My VBScript is as follows;

Dim myComponent, result, myArray

Set myComponent = Server.CreateObject("MyComponentProgID")
result = myComponent.FillArray(myArray)

Response.Write("IsArray = " & IsArray(myArray) & "<br/>")
Response.Write("UBound = " & UBound(myArray) & "<br/>")
Response.Write("TypeName = " & TypeName(myArray) & "<br/>")
Response.Write("Element 1 = " & myArray(1))

这将导致以下错误(由我对FillArray的调用所在的行触发)；

This results in the following error (triggered by the line where I make the call to FillArray);

错误类型:Microsoft VBScript运行时(0x800A0005)无效的过程调用或参数:"FillArray"

启动OLEView，IDL看起来像这样；

Firing up OLEView, the IDL looks like this;

HRESULT FillArray(
                [in, out] SAFEARRAY(BSTR)* arrayToFill, 
                [out, retval] VARIANT_BOOL* pRetVal);

我尝试将方法签名更改为以下内容；

I tried changing my method signature to the following;

public bool FillArray(ref object[] arrayToFill)

这导致了以下IDL；

Which resulted in the following IDL;

HRESULT FillArray(
                [in, out] SAFEARRAY(VARIANT)* arrayToFill, 
                [out, retval] VARIANT_BOOL* pRetVal);

但仍然是相同的无效的过程调用或参数'FillArray'"错误.

But still the same "Invalid procedure call or argument 'FillArray'" error.

最后，我尝试将方法签名更改为此；

Finally, I tried changing my method signature to simply this;

public bool FillArray(ref object arrayToFill)

哪个给出了以下IDL；

Which gave the following IDL;

HRESULT FillArray(
                [in, out] VARIANT* arrayToFill, 
                [out, retval] VARIANT_BOOL* pRetVal);

现在给出了一个新错误；

This gives a new error now;

Microsoft VBScript运行时(0x800A000D)类型不匹配

Microsoft VBScript runtime (0x800A000D) Type mismatch

现在仅在最后一行触发此错误，这是我尝试访问数组元素的时间.如果我注释掉最后一行，则得到以下输出；

This error is only fired off on the final line now, which is when I try to access an element of the array. If I comment the last line out, then I get the following output;

IsArray = True

IsArray = True

UBound = 39

UBound = 39

TypeName = String()

TypeName = String()

因此，很明显，变体被识别为数组，并且具有正确的类型.此外，UBound返回了正确数量的元素，但是由于某些未知原因，我无法访问任何元素.

So, apparently the variant is being recognised as an array, and of the correct type. Also, the correct number of elements are returned by UBound, but I cannot access any of the elements for some unknown reason.

有人知道这是什么原因吗?我自己做了一些研究，并遇到了以下链接；

Does anyone have any idea what might be causing this? I've done some research myself, and came across the following link;

http://connect.microsoft.com/VisualStudio/feedback/details/331632/marshaler-bug-with-vbscript-arrays

我不是100％地确定这是完全相同的问题，因为我没有在VBScript代码中以相同的方式声明数组.我衷心希望这不是一个相同的问题，因为我没有升级到.NET 4.0的范围.

I'm not 100% certain that it's the exact same issue, as I am not declaring my arrays in the same way in my VBScript code. I sincerely hope it's not the same issue, as I have no scope for upgrading to .NET 4.0.

推荐答案

我设法自己解决了这个问题.

I managed to work this one out myself.

事实证明，VBScript不处理非Variant类型的数组.因此，在我的C#代码中，我尝试了这一点；

It turns out that VBScript does not handle arrays which are not of type Variant. So, in my C# code I tried this;

public bool FillArray(ref object arrayToFill)
{
    string[] tmpArrayToFill = (string[])arrayToFill;
    ...
    arrayToFill = (object[])tmpArrayToFill
}

"..."指的是通过ref传递到arrayToFill的其他调用.

The "..." refers to further calls which pass along arrayToFill by ref.

不幸的是，这产生了完全相同的错误.

Unfortunately, this produced the exact same error.

使我走上解决之道的原因是"TypeName()"VBScript函数STILL将该类型视为"String()".我很好奇.NET代码中发生了什么，所以写了一个小测试；

What put me on the path to solving this was that the "TypeName()" VBScript function STILL saw the type as "String()". I was curious what was going on in the .NET code, so wrote a small test;

string[] stringArray = new string[1];
Console.WriteLine(stringArray.GetType());

object[] objectArray = (object[])stringArray;
Console.WriteLine(objectArray.GetType());

产生了以下内容；

System.String []

System.String[]

System.String []

System.String[]

这对我来说是个新闻-我没有意识到会是这种情况.我认为期望Object []作为第二种类型是合理的.

This was news to me - I didn't realise that this would be the case. I thought it reasonable to expect Object[] for the second type.

无论如何，我写了一个小的扩展方法来生成一个新对象[]

Anyway, regardless of that, I wrote up a small extension method to generate a new object[]

public static Array ToObjectArray(this Array input)
{
    if (input != null)
    {
        object[] objArray = new object[input.Length];
        input.CopyTo(objArray, 0);
        return objArray;
    }
    else
    {
        return null;
    } 
 }

这只是一个粗略的第一步-将添加更强大的错误处理和对锯齿状数组的支持.

This is just a rough first go at it - more robust error handling and support for jagged arrays are going to be added.

所以我的代码现在看起来像;

So my code now looks like;

public bool FillArray(ref object arrayToFill)
{
    string[] tmpArrayToFill = (string[])arrayToFill;
    ...
    arrayToFill = tmpArrayToFill.ToObjectArray();
}

现在，在VBScript中，TypeName返回 Variant()，我可以按预期访问数组.

And now, in the VBScript, TypeName returns Variant() and I can access the array as expected.

希望这将对将来遇到此问题的其他人有所帮助.

Hopefully this will help anybody else who runs into this problem in the future.

这篇关于“类型不匹配"；从COM +(VBScript)访问ref返回的数组时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！