django执行数据库查询之后实现返回的结果集转json

dic = {}
res = models.tables.objects.all().order_by('-id')
L = []
b = model_to_dict(res)
L.append(b)
dic['code'] = '1'
dic['message'] = ''
dic['result'] = L
return HttpResponse(json.dumps(dic, ensure_ascii=False))

L = []
cursor.execute(sql)
desc = cursor.description # 获取字段的描述，默认获取数据库字段名称
data_dict = [dict(zip([col[0] for col in desc], row)) for row in
       cursor.fetchall()] # 列表表达式把数据组装起来
for online_dict in data_dict:  # 判断如果时间类型要转出字符串，后期碰到什么类型不能转的在加
  for key in online_dict:
    if type(online_dict[key]) in (datetime, pymysql.TIMESTAMP, pymysql.DATE,
                   pymysql.TIME, YEAR):
      online_dict[key] = online_dict[key].strftime(
        "%Y-%m-%d %H:%M:%S")
    else:
      pass
  L.append(online_dict)
conn.commit()
cursor.close()
conn.close()
dic['code'] = '2'
dic['message'] = ''
dic['result'] = L
return HttpResponse(json.dumps(dic, ensure_ascii=False))