Created
February 17, 2013 23:01
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from django.forms.models import model_to_dict | |
class ModelDiffMixin(object): | |
""" | |
A model mixin that tracks model fields' values and provide some useful api | |
to know what fields have been changed. | |
""" | |
def __init__(self, *args, **kwargs): | |
super(ModelDiffMixin, self).__init__(*args, **kwargs) | |
self.__initial = self._dict | |
@property | |
def diff(self): | |
d1 = self.__initial | |
d2 = self._dict | |
diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]] | |
return dict(diffs) | |
@property | |
def has_changed(self): | |
return bool(self.diff) | |
@property | |
def changed_fields(self): | |
return self.diff.keys() | |
def get_field_diff(self, field_name): | |
""" | |
Returns a diff for field if it's changed and None otherwise. | |
""" | |
return self.diff.get(field_name, None) | |
def save(self, *args, **kwargs): | |
""" | |
Saves model and set initial state. | |
""" | |
super(ModelDiffMixin, self).save(*args, **kwargs) | |
self.__initial = self._dict | |
@property | |
def _dict(self): | |
return model_to_dict(self, fields=[field.name for field in | |
self._meta.fields]) |
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