When passing a parameter to a COM Component's method in
Active Server Pages (ASP) using VBScript, either the following error occurs:
Microsoft VBScript runtime error '800a000d' Type
mismatch
Or the value stored in the variable passed to the
method is not changed.
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VBScript will pass parameters to a method by value if the
argument's data type is NOT declared as a variant and the parameter is passed
by reference if the argument's data type is declared as variant by the method.
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Parameters to be passed as [out] parameters (that is, by
reference) to a method should always be declared as a pointer to a variant data
type by the method, while [in] parameters (that is, passed by value) can be
declared as any type.
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This behavior is by design.
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Steps to Reproduce Behavior
| 1. | Create an ATL DLL Project called "ByRefProj." |
| 2. | Insert an ATL Object named "ByRefObj." |
| 3. | Add and implement the method.
| a. | Add a method with the following information:
Method Name: ByRefMethod
Parameters : [out]BSTR* bstrVal
| | b. | Implement the method as follows:STDMETHODIMP CByRefObj::ByRefMethod( BSTR* bstrVal )
{
CComBSTR bstrRtnVal = L"This variable is passed by Reference";
*bstrVal = bstrRtnVal.Detach();
return S_OK;
}
|
|
| 4. | Create an Active Server Pages (ASP) page that calls this
method:<%
Dim objTest, strByRefVal
Set objTest = Server.CreateObject("ByRefProj.ByRefObj")
objTest.ByRefMethod strByRefVal
%> |
| 5. | Run ASP, and the following error occurs: Microsoft VBScript runtime error '800a000d'
Type mismatch:
'ByRefMethod' |
To fix this problem, change the type to VARIANT:
| 1. | Change the IDL declaration in the ByRefProj.idl file to:
[id(1), helpstring("method ByRefMethod")] HRESULT ByRefMethod([out] VARIANT* vVal);
|
| 2. | Change the method in the .h and .cpp file. Change the
method as follows:// Where m_bstr is a BSTR member of SomeComObject.
vVal->vt = VT_BSTR;
vVal->bstrVal = m_bstr.Copy();
|
| 3. | Recompile. |
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For additional information, click the article number below
to view the article in the Microsoft Knowledge Base:
244012 (http://support.microsoft.com/kb/244012/EN-US/) INFO: Type Mismatch Errors When You Pass Parameters from ASP to a Visual Basic Component
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