[PyQt] PyQt Custom user types with QVariants and QMetaTypes

Justin Rosen jmylesrosen at gmail.com
Mon Jun 20 21:44:47 BST 2011

Hey all,

I've been struggling the past few days with trying to wrap my mind around
how PyQt has implemented QVariants and QMetaTypes.  In short I'm trying to
register/declare a custom user type that will be picked up by

I've found a few postings related to the topic, but have been unable to get
a working example.  I'm using Qt 4.6.1 and PyQt 4.7.2 on Linux Red Hat
Enterprise 5.5

The FAQ clearly states that this is doable: "Can I store a python object
reference in a QVariant?"<http://article.gmane.org/gmane.comp.python.pyqt-pykde/11833>
And the original thread covering the issue in the FAQ: Construct QVariant
from object of user

I'm able to store a python object on a QVariant and get the object back, For
example the following class Triplet:
>>> class Triplet:
...    def __init__(self):
...        self.first, self.second, self.third = (-1, -1, -1)

>>> t = Triplet()
>>> tv = QtCore.QVariant(t)
>>> assert tv.toPyObject() is t

But I can't seem to derive the type/userType as being a Triplet.  Comes back
as PyQt_PyObject and UserType:
>>> tv.type()
>>> tv.typeName()
>>> tv.typeToName(tv.type())
>>> tv.userType()
>>> tv.typeToName(tv.userType())

What am I doing wrong?  The FAQ says that new python types are automatically
registered, but I keep getting the same PyObject type.
"The QVariant() ctor will now register new Python types automatically. I've
also wrapped QMetaType.type() and overloaded it so that you can pass a
Python type. I think this is enough for what you need."

In a previous post Matt Newell posted some code that achieves this, but I'm
assuming this has been superseded by integration with sip?:
>>> class A: pass
>>> metaTypeId = registerPythonQMetaType(A)
>>> print metaTypeId
>>> qv = qvariantFromPyObject(A())
>>> qv
<PyQt4.QtCore.QVariant object at 0xb7d2ec2c>
>>> qv.userType()
>>> print qv.typeName()
>>> pyObjectFromQVariant(qv)
<__main__.A instance at 0xb65391ec>

Thanks, any help would be greatly appreciated!
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