IndexError：元組索引超出範圍 - 字符串格式化

Question

我正在做一個小imageboard之類的話，而我試圖做一個MySQL插入，但這段代碼是拋出一個錯誤：

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))) 

而這裏的誤差（上獵鷹/ WSGI上運行此）：

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 

我如何糾正呢？

Answer 1

你在你的.format輸入中有額外的括號，它正在這樣做（將輸入視爲單個元組）。

概念證明：

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

---

所以不是這個

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))) 

做到這一點

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)) 

正如下面的評論@chepner筆記，更好的辦法要做到這一點將是使用下面，其中E中的%s通過使用作爲第二個參數傳遞給執行該元組中的光標填充：

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))