[PyQt] Obtaining a pointer to sqlite3 handle in PyQt5's binding of QtSqlDriver - a QVariant problem

[Phil Thompson]

On 11/10/2019 15:23, Andrej Radovic wrote:
> Hello everyone, it's my first post here, I'll get straight to the 
> point.
> 
> I'm trying to register some functions in sqlite within my PyQt5 app. To 
> do
> so
> within Python, I'm trying to obtain the pointer (actually, `sqlite3 
> **`) to
> the
> sqlite instance, so I could use sqlite3_create_function
> (https://sqlite.org/c3ref/create_function.html) through Python's
> `ctypes` (https://docs.python.org/3/library/ctypes.html) and register 
> my
> function.
> 
> When doing this in Qt5 instead of Python, you just use
> `QSqlDriver::handle()`
> (https://doc.qt.io/qt-5/qsqldriver.html#handle), which returns a 
> QVariant
> containing the address. You cast the `QVariant.data()` appropriately 
> and off
> you go. When I try to obtain the handle in Python , I get:
> 
>     db.driver().handle()
>     TypeError: unable to convert a C++ 'sqlite3*' instance to a Python
> object
> 
> I found that this error is generated within the C++ part of qpycore
> (qpy/QtCore/qpycore_chimera.cpp:1539).
> The code shows that a QVariant containing a pointer to an unknown type
> cannot
> be translated to a Python object. However, I don't need a Python 
> object,
> just a
> pointer I can use with ctypes.
> 
> Does anyone know of a way to do this? Thanks!

In tonight's snapshot it will be converted to a voidptr object...

https://www.riverbankcomputing.com/static/Docs/PyQt5/api/sip/sip-module.html#voidptr

Is that enough?

Phil