[QGIS-Developer] For an enum in pyqgis, how do I list all members and do reverse lookups?

[Julien Cabieces]

You're right, the actual code doesn't work in my environment either.

PyQt is also a wrapper of Qt made with sip, so we should get the same
result in sip.

QCborSimpleType is actually and exception because it fails also with
other Qt enums that I have tested (Qt.ItemDataRole for instance).

I don't get what happen here, the script supposedly not work like it
should. But it worked before, so I'm wondering what happened. Maybe SIP
changed things and introduced the mappingproxy thing.

I'd have to investigate a bit...

If anyone has information on this, please share :)

Regards,
Julien



> Thanks. And that function works well for e.g. qgis.qgis.PyQt.Qt.QCborSimpleType. Which by the way has type
> enum.EnumType, and is defined in QGIS/share/qgis/python/qgis/PyQt/Qt.py.
>
> But Im talking about an "enum" created by SIP. Such an "enum" is a class definition, with 'int' as its only parent class. It
> has around 14 enum-members, e.g. "Symbology". But there is no way of getting a complete list of them. Neither with _
> _dict__ nor dir. 
>
>>>> from qgis.core import QgsMapLayer
>>>> QgsMapLayer.StyleCategory
> <class 'qgis._core.QgsMapLayer.StyleCategory'>
>>>> type(QgsMapLayer.StyleCategory)
> <class 'sip.enumtype'>
>>>> QgsMapLayer.StyleCategory.__dict__
> mappingproxy({'__module__': 'qgis._core', '__or__': <slot wrapper '__or__' of 'StyleCategory' objects>, '__ror__': <slot
> wrapper '__ror__' of 'StyleCategory' objects>, '__dict__': <attribute '__dict__' of 'StyleCategory' objects>, '__doc__': None,
> '__reduce__': <method '_pickle_enum' of 'StyleCategory' objects>, 'baseClass': <class 'qgis._core.QgsMapLayer'>})
>>>> dir(QgsMapLayer.StyleCategory)
> ['__abs__', '__add__', '__and__', '__bool__', '__ceil__', '__class__', '__delattr__', '__dict__', '__dir__', '__divmod__', '__doc__',
> '__eq__', '__float__', '__floor__', '__floordiv__', '__format__', '__ge__', '__getattribute__', '__getnewargs__', '__getstate__',
> '__gt__', '__hash__', '__index__', '__init__', '__init_subclass__', '__int__', '__invert__', '__le__', '__lshift__', '__lt__', '__mod__',
> '__module__', '__mul__', '__ne__', '__neg__', '__new__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', '__rdivmod__',
> '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', '__round__', '__rpow__',
> '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', '__rxor__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__',
> '__truediv__', '__trunc__', '__xor__', 'as_integer_ratio', 'baseClass', 'bit_count', 'bit_length', 'conjugate', 'denominator',
> 'from_bytes', 'imag', 'is_integer', 'numerator', 'real', 'to_bytes']
>>>> QgsMapLayer.StyleCategory.Symbology # but the members are there !
> 2
>
> On Wed, Jul 2, 2025 at 10:00 AM Julien Cabieces <julien.cabieces at oslandia.com> wrote:
>
>  Hi,
>
>  If you want an example, it has been done here: 
>  https://github.com/qgis/QGIS/blob/cb48529abf5bd81e3c97d09809e3d56e51c943bd/scripts/pyqt5_to_pyqt6/pyqt5_to_pyqt6.py#L796
>  
>
>  You have to use __dict__. But I'm not sure this is a good thing to use
>  this in a plugin. The script I mention is an helper for migration from
>  qt5 to qt6, so it's kind of special.
>
>  Regards,
>  Julien
>
>  > Happy summer to all of you :)
>  >
>  > It seems in the Python bindings produced by SIP, a C++ enum is just a Python class with a certain structure. And
>  with little/none possibility of
>  > introspection.
>  >
>  > But how can I get a list with all enum-members (e.g. Symbology, Fields) of that enum?
>  >
>  > dir(QgsMapLayer.StyleCategory) does not list them, and QgsMapLayer.StyleCategory.__members__ is undefined. 
>  >
>  > Do I really have to hard code the member names into my plugin, if I want to iterate over all of them?
>  >
>  > Sincerely, Thomas
>  >
>  > _______________________________________________
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>
>  -- 
>
>  Julien Cabieces
>  Senior Developer at Oslandia
>  julien.cabieces at oslandia.com

-- 

Julien Cabieces
Senior Developer at Oslandia
julien.cabieces at oslandia.com