@Vijay, thanks. I also had a similar idea, but I was surprised it was not somewhere already implemented.
Then I found __subclasses__() as mentioned here http://stackoverflow.com/questions/40353219/updating-django-mixin-subclassed-instances/40353284#40353284 It works (Python 3.3, Django 1.8) ;) Thx, R On Tuesday, November 1, 2016 at 7:20:18 PM UTC+1, Vijay Khemlani wrote: > > You could use a metaclass to keep track of all the classes that inherit > from a given one, in a pure Python way it would be something like this > > class PluginMeta(type): > # we use __init__ rather than __new__ here because we want > # to modify attributes of the class *after* they have been > # created > def __init__(cls, name, bases, dct): > if not hasattr(cls, 'registry'): > # this is the base class. Create an empty registry > cls.registry = {} > else: > # this is a derived class. Add cls to the registry > interface_id = name.lower() > cls.registry[interface_id] = cls > super(PluginMeta, cls).__init__(name, bases, dct) > class Plugin(object): > __metaclass__ = PluginMeta > > > > So, all the classes that inherit from Plugin are stored in > Plugin.registry. Not sure if it works for mixins though. > > On Mon, Oct 31, 2016 at 4:03 PM, Radek Svarz <[email protected] > <javascript:>> wrote: > >> Hi, >> >> I am using my custom permission mixin on several of my apps's models (not >> all). >> >> For the case when I need to merge from the "old - context" permission to >> the "new - context" permission I want to have function which changes the >> corresponding permission reference attribute in all models, which >> subclassed this mixin. >> >> How do I know which models subclassed this permission mixin and that they >> have the inherited permission reference attribute? >> >> In fact I want to have such function in my mixin: >> >> @classmethod >> def merge_to(cls, from_perm_context, to_perm_context): >> >> perm_context_models = [] # How to get this? >> >> try: >> with transaction.atomic(): >> for model in perm_context_models: >> model.objects.filter( >> perm_context=from_perm_context, >> ).update(perm_context=to_perm_context) >> except IntegrityError as e: # or DatabaseError >> raise e >> >> >> >> >> Thanks, >> >> Radek >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> Visit this group at https://groups.google.com/group/django-users. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-users/576474f7-dace-4986-b121-0eb2e5428122%40googlegroups.com >> >> <https://groups.google.com/d/msgid/django-users/576474f7-dace-4986-b121-0eb2e5428122%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/c34a9bb6-01ee-49c5-9c0e-fa9cce342b7d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
