I'm trying to generate models that record some fields of other models, using metaclass.
My plan is to copy recording_fields of recording_model(which is a model to be recorded), and register them on the subclasses of RecordModel via contribute_to_class(cls,name) method of django's Field.
In this way, it will be able to automatically create records whenever one of recording_model's recording_fields has been changed, using signals.
The problem is that I have to create exactly same Field instances with recording_model's, including database constraints and requirements (e.g. max_length argument).
So the situation is
from django.models import Model
from django.models.base import ModelBase
class TimeStampedModel(Model):
...
class Meta:
abstract = True
...
class RecordModelMetaClass(ModelBase):
def __init__(cls, name, bases, attrs):
...
# Register 'recording_fields' of 'recording_model'
# to subclasses of RecordModel (not reference, deep copy)
# using `contribute_to_class`.
...
class RecordModel(TimeStampedModel):
__metaclass__ = RecordModelMetaClass
recording_model = NotImplemented
recording_fields = NotImplemented
class Meta(TimeStampedModel.Meta):
abstract = True
where RecordModel will be the abstract base class of all records.
I know I can use Model._meta.get_field() method to retrieve an Field instance of a model, but what I need is copy of an instance, not reference.
Is there any way to make an deep copy of an Field instance in django?
