python - 索引错误 : tuple index out of range -- String formatting

Question

我正在制作一些类似图像板的东西，我正在尝试插入 MySQL，但是这段代码会引发错误:

curs.execute("INSERT INTO posts(date,replies,title,link,text,userip,username) VALUES('{}',{},'{}','{}','{}','{}','{}');".format((self.date.isoformat(),self.replies,self.title,self.embed,self.text,self.userip,self.username)))

这是错误(在 Falcon/WSGI 上运行):

2015-05-05 17:37:14,135 :Traceback (most recent call last):
2015-05-05 17:37:14,136 :  File "/bin/user_wsgi_wrapper.py", line 130, in __call__
2015-05-05 17:37:14,136 :    self.error_log_file.logger.exception("Error running WSGI application")
2015-05-05 17:37:14,136 :  File "/usr/lib/python2.7/logging/__init__.py", line 1185, in exception
2015-05-05 17:37:14,136 :    self.error(msg, *args, **kwargs)
2015-05-05 17:37:14,136 :  File "/usr/lib/python2.7/logging/__init__.py", line 1178, in error
2015-05-05 17:37:14,136 :    self._log(ERROR, msg, args, **kwargs)
2015-05-05 17:37:14,136 :  File "/usr/lib/python2.7/logging/__init__.py", line 1270, in _log
2015-05-05 17:37:14,137 :    record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra)
2015-05-05 17:37:14,137 :  File "/usr/lib/python2.7/logging/__init__.py", line 1244, in makeRecord
2015-05-05 17:37:14,137 :    rv = LogRecord(name, level, fn, lno, msg, args, exc_info, func)
2015-05-05 17:37:14,137 :  File "/usr/lib/python2.7/logging/__init__.py", line 284, in __init__
2015-05-05 17:37:14,137 :    self.threadName = threading.current_thread().name
2015-05-05 17:37:14,137 :  File "/usr/lib/python2.7/threading.py", line 1160, in currentThread
2015-05-05 17:37:14,137 :    return _active[_get_ident()]
2015-05-05 17:37:14,137 :  File "/bin/user_wsgi_wrapper.py", line 122, in __call__
2015-05-05 17:37:14,138 :    app_iterator = self.app(environ, start_response)
2015-05-05 17:37:14,138 :  File "/home/isitcoldinfallschurch/.virtualenvs/myvirtualenv/local/lib/python2.7/site-packages/falcon/api.py", line 175, in __call__
2015-05-05 17:37:14,138 :    responder(req, resp, **params)
2015-05-05 17:37:14,138 :  File "./new.py", line 89, in on_post
2015-05-05 17:37:14,139 :    thispost.insertdb()
2015-05-05 17:37:14,139 :  File "./new.py", line 57, in insertdb
2015-05-05 17:37:14,140 :    curs.execute("INSERT INTO posts(date,replies,title,link,text,userip,username) VALUES('{}',{},'{}','{}','{}','{}','{}');".format((self.date.isoformat(),self.replies,self.title,self.embed,self.text,self.userip,self.username)))
2015-05-05 17:37:14,140 :IndexError: tuple index out of range

我该如何纠正这个问题？

Answer 1

您的 .format 输入中有额外的括号，它正在执行此操作(将输入视为单个元组)。

概念验证:

>>> "{}{}".format((1,2))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: tuple index out of range
>>> "{}{}".format(1,2)
'12'

---

所以不是这个

curs.execute("INSERT INTO posts(date,replies,title,link,text,userip,username) VALUES('{}',{},'{}','{}','{}','{}','{}');".format((self.date.isoformat(),self.replies,self.title,self.embed,self.text,self.userip,self.username)))

这样做

curs.execute("INSERT INTO posts(date,replies,title,link,text,userip,username) VALUES('{}',{},'{}','{}','{}','{}','{}');".format(self.date.isoformat(),self.replies,self.title,self.embed,self.text,self.userip,self.username))

正如@chepner 在下面的评论中指出的那样，更好的方法是使用下面的代码，其中 %s 由游标使用元组作为第二个参数传递给执行:

curs.execute("INSERT INTO posts(date,replies,title,link,text,userip,username) VALUES(%s, %s, %s, %s, %s, %s, %s);", (self.date.isoformat(), self.replies, self.title, self.embed, self.text, self.userip, self.username))