Object instance in a singleton class dissapears

[vieraci]

I'm having some trouble with a singleton class where I create a QSqlQuery object, execute it and access the results from anywhere in the app from an instance.

It works except in one place it crashes the app.

Header file:

class GlobalDataInstance
{
  public:
      static GlobalDataInstance* Instance();
      QStringList getCatItems(int cat_code, int start, int end, bool concatentReturnCode);
      bool refreshCatCodes();
  protected:
      GlobalDataInstance();
      GlobalDataInstance(const GlobalDataInstance&);
      GlobalDataInstance& operator= (const GlobalDataInstance&);
  private:
      static GlobalDataInstance* pinstance;
// Can't make categoryCodes static, it doesn't compile, or it crashes immediately.
      QSqlQuery categoryCodes;
};

class GlobalDataInstance
{
  public:
      static GlobalDataInstance* Instance();
      QStringList getCatItems(int cat_code, int start, int end, bool concatentReturnCode);
      bool refreshCatCodes();
  protected:
      GlobalDataInstance();
      GlobalDataInstance(const GlobalDataInstance&);
      GlobalDataInstance& operator= (const GlobalDataInstance&);
  private:
      static GlobalDataInstance* pinstance;
// Can't make categoryCodes static, it doesn't compile, or it crashes immediately.
      QSqlQuery categoryCodes;
};

To copy to clipboard, switch view to plain text mode 

This method called in Main() after I create the first instance:

bool GlobalDataInstance::refreshCatCodes()
{
    categoryCodes.exec("SELECT cat_code, cat_text, return_value FROM global_cat_codes order by cat_code, return_value");
        return true;
}

bool GlobalDataInstance::refreshCatCodes()
{
    categoryCodes.exec("SELECT cat_code, cat_text, return_value FROM global_cat_codes order by cat_code, return_value");
        return true;
}

To copy to clipboard, switch view to plain text mode 

Then when I open a window I get an instance pointer and call this method to fill some comboboxes from various places in the query:

QStringList GlobalDataInstance::getCatItems(int cat_code, int start, int end, bool concatentReturnCode)
{
    QStringList list;
    list.clear();
    categoryCodes.first();
    while (categoryCodes.next())
    {
        int catCode = categoryCodes.value(0).toInt();
        if (catCode > cat_code)
            break;
        if (catCode == cat_code)
        {
            QString oper = categoryCodes.value(2).toString();
            if (oper.toInt() >= start)
            {
                if (oper.toInt() > end)
                    break;
                if (concatentReturnCode)
                    list <<  oper + " " + categoryCodes.value(1).toString();
                else
                    list <<  categoryCodes.value(1).toString();
            }
        }
    }
    return list;
}

QStringList GlobalDataInstance::getCatItems(int cat_code, int start, int end, bool concatentReturnCode)
{
    QStringList list;
    list.clear();
    categoryCodes.first();
    while (categoryCodes.next())
    {
        int catCode = categoryCodes.value(0).toInt();
        if (catCode > cat_code)
            break;
        if (catCode == cat_code)
        {
            QString oper = categoryCodes.value(2).toString();
            if (oper.toInt() >= start)
            {
                if (oper.toInt() > end)
                    break;
                if (concatentReturnCode)
                    list <<  oper + " " + categoryCodes.value(1).toString();
                else
                    list <<  categoryCodes.value(1).toString();
            }
        }
    }
    return list;
}

To copy to clipboard, switch view to plain text mode 

From that window, I open another and again do the same thing, but from there it crashes.
In debug it appears that categoryCodes dissapears from scope and I don't see how.
I tried to change QSqlQuery to a pointer and created it on the heap in the ctr, but it crashes immediately. What am I dong wrong ?

[caduel]

show us your Instance(), please

[vieraci]

Oh !! I see what I did, I was calling initForm before creating the instance.
I should stop working when I get tired


In ctor:

initForm();
globalData = GlobalDataInstance::Instance();

initForm();
globalData = GlobalDataInstance::Instance();

To copy to clipboard, switch view to plain text mode 

In use:

void AddressDialog::initForm()
{
    m_ui->cbAddressType->addItems(globalData->getCatItems(1,1,10,false));
    m_ui->cbAddressType->installEventFilter(this);
}

void AddressDialog::initForm()
{
    m_ui->cbAddressType->addItems(globalData->getCatItems(1,1,10,false));
    m_ui->cbAddressType->installEventFilter(this);
}

To copy to clipboard, switch view to plain text mode