django-mergeobject-experime.../fkreplace/__init__.py

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def merge(from_obj, to_obj):
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if not isinstance(from_obj, type(to_obj)):
raise ValueError("both objects must be of the same type")
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if from_obj.pk == to_obj.pk:
raise ValueError("cannot merge object with itself")
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for related in from_obj._meta.get_all_related_objects():
accessor_name = related.get_accessor_name()
varname = related.field.name
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if related.multiple:
field = getattr(from_obj, accessor_name)
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field.all().update(**{varname: to_obj})
elif related.one_to_one:
try:
field = getattr(from_obj, accessor_name)
try:
getattr(to_obj, accessor_name)
except Exception as e:
# doesn't exist, safe to overwrite
setattr(field, varname, to_obj)
field.save()
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except Exception as e:
# from_obj one to one isn't set, skip
pass
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else:
import pdb; pdb.set_trace()
raise Exception('unknown code path')
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for related in from_obj._meta.get_all_related_many_to_many_objects():
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accessor_name = related.get_accessor_name()
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varname = related.field.name
if not accessor_name:
# not set in M2M to self, but varname will match
accessor_name = varname
field = getattr(from_obj, accessor_name)
if related.many_to_many:
for f in field.all():
getattr(f, varname).remove(from_obj)
getattr(f, varname).add(to_obj)