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Qt-interest Archive, May 2007
Why does not querySubObject work for COM objects?

• Subject: Why does not querySubObject work for COM objects?
• From: Lingfa Yang <lingfa@xxxxxxx>
• Date: Wed, 09 May 2007 13:23:19 -0400
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Why does not querySubObject work for COM objects?

querySubObject() is a function of QAxBase, and  QAxBase is inherited by 
QAxObject and QAxWidget to export COM and ActiveX

The next test assume you have a registered server, if not just type:
idc c:\qt\4.3.0\examples\activeqt\hierarchy\release\hierarchyax.dll  
/regserver

Case 1: The ActiveX works:

        QString widget1("This is the first widget.");
        QString widget2("Here comes the 2nd.");
        activeX->dynamicCall("createSubWidget(QString)", widget1);
        activeX->dynamicCall("createSubWidget(QString)", widget2);

        QAxObject * result = 
activeX->querySubObject("subWidget(QString)", widget1); // works fine!
        QString text1 = result->dynamicCall("label()").toString(); // right!
        result->dynamicCall("setLabel(QString)","setLabel(QString)"); // 
right!

Case 2: The COM does not work:
            hierarchyaxLib::IQParentWidget com(fmt->Object());

        QString widget1("This is the first widget.");
        QString widget2("Here comes the 2nd.");
        com.dynamicCall("createSubWidget(QString)", widget1); // ok
        com.dynamicCall("createSubWidget(QString)", widget2);

        QAxObject * result = com.querySubObject("subWidget(QString)", 
widget1); // crash ???
        QString text1 = result->dynamicCall("label()").toString();
        result->dynamicCall("setLabel(QString)","setLabel(QString)");

Question:
        Why "activeX->querySubObject" works, but "com.querySubObject" 
does not?

Thanks in advance,
Lingfa

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