Delete Stats stacker

delete_stats.py

class DeleteStats(object): 
    """ 
    Object that allows stacking the results of .delete() 
 
    You can initialise it with or without data: 
 
        > stats = DeleteStats() 
 
        or 
 
        > stats = DeleteStats(some_queryset.delete()) 
 
    You can stack delete results from different types of querysets/model instances: 
 
        > stats = DeleteStats() 
        > 
        > stats.extend(SomeModel.objects.filter(...).delete()) 
        > 
        > stats.extend(SomeOtherModel.objects.filter(...).delete()) 
        > 
        > stats.extend(some_object.delete()) 
 
    It can be unpacked like a tuple, so that it behaves the way that Django's API does: 
 
        > total_deleted, removed_by_model = stats 
 
    And it print out everything using a logger: 
 
        > logger = logging.getLogger(__name__) 
        > stats.log(logger) 
    """ 
    def __init__(self, delete_output=None): 
        super(DeleteStats, self).__init__() 
        self.total_removed = 0 
        self.removed_by_model = defaultdict(int) 
 
        if delete_output: 
            self.extend(delete_output) 
 
    def extend(self, delete_output): 
        total_removed, removed_by_model = delete_output 
 
        self.total_removed += total_removed 
        for _model, _count in removed_by_model.iteritems(): 
            self.removed_by_model[_model] += _count 
 
        return self 
 
    def __getitem__(self, index): 
        # Pretend to be a tuple to match how the django API returns deletes 
        if index == 0: 
            return self.total_removed 
        elif index == 1: 
            return self.removed_by_model 
        raise IndexError() 
 
    def log(self, _logger): 
        _logger.info("Deleted {} objects in total".format(self.total_removed)) 
 
        for model_name, count in self.removed_by_model.iteritems(): 
            _logger.info("- {model_name} deleted: {count}".format( 
                model_name=model_name, count=count 
            ))