【Python】Django 聚合 Count与Sum用法，注意点

代码示例：

from django.db.models import Sum, Count
            #alarm_sum_group_items = models.FILE_PROTECT_ALARM.objects.filter(**condition).filter(device_hash=tmp_dict['device_hash']).values('device_hash').annotate(alarm_sum=Sum('cmn_merge_count'))
            #tmp_dict['customer_id'] = customer_id
            #tmp_dict['alarm_sum'] = alarm_sum_group_items[0]['alarm_sum'] if (len(alarm_sum_group_items)!=0) else 0
            
            alarm_sum = models.FILE_PROTECT_ALARM.objects.filter(**condition).filter(device_hash=tmp_dict['device_hash']).aggregate(Sum("cmn_merge_count"))
            # {'cmn_merge_count__sum': None}
            tmp_dict['alarm_sum'] = alarm_sum['cmn_merge_count__sum'] if (alarm_sum['cmn_merge_count__sum'] is not None) else 0
            
            rule_sum = models.FILE_PROTECT_RULE_UPDATE.objects.filter(customer_id=customer_id).filter(device_hash=tmp_dict['device_hash']).aggregate(Count("id"))
            # {'id__count': 0}
            tmp_dict['rule_sum'] = rule_sum['id__count']