在for循环中无法访问Django ImageField

如何解决在for循环中无法访问Django ImageField

我正在使用telebot创建Telegram bot和Django进行模型管理。

当我尝试通过循环向多个用户发送帖子时，在尝试访问ImageField时出现错误

这是我的代码

def empty_generator(*kwargs):
return types.InlineKeyboardMarkup()

@bot.message_handler(commands=['test'])
def test_send(message):
    post = Mailing.objects.get(id=79)
    for i in range(0,3):
        print(post.file,len(post.file))
        send_generator_with_preview(message.chat.id,post,post.broadcast_language,empty_gener)


def send_generator_with_preview(chat_id,ln,generator):
    if (post.file):
        if post.text:
            # No photo post
            bot.send_photo(chat_id,caption=post.text,photo=post.file,reply_markup=generator(post,ln),parse_mode='markdown')
        else:
            # No text post
            bot.send_photo(chat_id,parse_mode='markdown')
    else:
        # No Image post
        bot.send_message(chat_id,text=post.text,parse_mode='markdown')

不幸的是，尝试运行此代码将导致错误：

>  ERROR - TeleBot: "ApiException occurred,args=('A request to the
> Telegram API was unsuccessful. The server returned HTTP 400 Bad
> Request. Response
> body:\n[b\'{"ok":false,"error_code":400,"description":"Bad Request:
> file must be non-empty"}\']',) Traceback (most recent call last):  
> File
> "/Users/number16/Documents/GitHub/urus-master/venv/lib/python3.7/site-packages/telebot/util.py",> line 62,in run
>     task(*args,**kwargs)   File "/Users/number16/Documents/GitHub/urus-master/urus/bot.py",line 1628,> in test_send
>     send_generator_with_preview(message.chat.id,empty_gener)   File
> "/Users/number16/Documents/GitHub/urus-master/urus/bot.py",line 1691,> in send_generator_with_preview
>     reply_markup=generator(post,parse_mode='markdown')   File "/Users/number16/Documents/GitHub/urus-master/venv/lib/python3.7/site-packages/telebot/__init__.py",> line 700,in send_photo
>     parse_mode,disable_notification,timeout))   File "/Users/number16/Documents/GitHub/urus-master/venv/lib/python3.7/site-packages/telebot/apihelper.py",> line 315,in send_photo
>     return _make_request(token,method_url,params=payload,files=files,method='post')   File
> "/Users/number16/Documents/GitHub/urus-master/venv/lib/python3.7/site-packages/telebot/apihelper.py",> line 69,in _make_request
>     return _check_result(method_name,result)['result']   File "/Users/number16/Documents/GitHub/urus-master/venv/lib/python3.7/site-packages/telebot/apihelper.py",> line 88,in _check_result
>     raise ApiException(msg,method_name,result) telebot.apihelper.ApiException: A request to the Telegram API was
> unsuccessful. The server returned HTTP 400 Bad Request. Response body:
> [b'{"ok":false,"description":"Bad Request: file must
> be non-empty"}']

在第一次运行时，一切正常，并发送了一条消息，但是第二次运行send_photo时，出现此错误。我检查了文件是否存在，并且在那里。

这是模特

class Mailing(models.Model):
    user = models.ForeignKey(User,on_delete=models.SET_NULL,null=True)
    chat = models.ForeignKey(Chat,null=True)
    message = models.ForeignKey(Message,null=True)
    recipients = models.CharField(max_length=1024,null=True,blank=True)
    broadcast_language = models.CharField(max_length=1024,blank=True)
    text = models.TextField(default='',blank=True)
    file = models.ImageField(upload_to='./mailing',null=True)
    datetime = models.DateTimeField(default=datetime.now,blank=True)
    post_at = models.DateTimeField(blank=True,null=True)

那我在做什么错了？

我想出了一个行之有效的糟糕解决方案，但我想正确地做到这一点。 这是解决方案，我知道这是错误的。 它在循环的每次迭代中都调用Mailing对象：

def send_generator_with_preview(chat_id,generator):
    new_post = Mailing.objects.get(id=post.id)
    if (new_post.file):
        if new_post.text:
            # No photo post
            bot.send_photo(chat_id,caption=new_post.text,photo=new_post.file.read(),reply_markup=generator(new_post,parse_mode='markdown')
        else:
            # No text new_post
            bot.send_photo(chat_id,parse_mode='markdown')
    else:
        # No Image new_post
        bot.send_message(chat_id,text=new_post.text,parse_mode='markdown')

帮我找出我做错了什么，或者与远程机器人的工作方式有关。

我认为这与在发送消息末尾释放.file对象有关