invalid literal for int() with base 10

invalid literal for int() with base 10

python 数据库编程问题
用了django和sqlite3

Log 是个数据库模板,包含一个时间列

code:
log_list=Log.objects.all()
log=log_list[0]

error:
invalid literal for int with base 10 2008-11-7...

怎么解决呢?
看一log模板的定义
class Log(models.Model):
    time = models.TimeField()
    action = models.CharField(maxlength=20)
    device_id = models.IntegerField()
    brand = models.CharField(maxlength=50)
    mode = models.CharField(maxlength=50)
    os = models.CharField(maxlength=50)

这样定义有什么问题么?请指教
谁来指导一下呢,急