IndexError: tuple index out of range -- String formatting

Question

I'm making a little imageboard kind of thing, and I'm trying to do a MySQL insert, but this piece of code is throwing an error:

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)))

And here's the error (running this on top of Falcon/WSGI):

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

How can I correct this?

Your second set of` { } are missing single quotes VALUES('{}',{},'{}','{}','{}','{}','{}') — Cory Kramer
– Cory Kramer, Commented May 5, 2015 at 17:55
Why are you creating another tuple? Simply do format(self.date.isoformat(),self.replies,self.title,self.embed,self.text,self.userip,self.username) — thefourtheye
– thefourtheye, Commented May 5, 2015 at 17:55
@Cyber If the value is actually a number, then you don't need them I guess — thefourtheye
– thefourtheye, Commented May 5, 2015 at 17:57

Anshul Goyal · Accepted Answer · 2015-05-05 18:07:16Z

3

You have extra brackets in your .format input which is doing this (treating the inputs as a single tuple).

Proof of concept:

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

So instead of this

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)))

do this

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))

As @chepner notes in the comments below, a better way to do this would be to use the below, where the %s are filled by the cursor using the tuple passed as the second argument to execute:

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))

edited May 5, 2015 at 18:07

answered May 5, 2015 at 17:58

Anshul Goyal

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9 Comments

chepner Over a year ago

I don't know what type curs is, but I strongly suspect the OP should not be using format at all to generate the SQL statement.

chepner Over a year ago

Something like

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))

Anshul Goyal Over a year ago

@chepner You are right, the type can not be accurately inferred, though I think it is a cursor; curs can be short for cursor and it has the .execute method as well.

chepner Over a year ago

Because with format, a value with a single quote will change the parsing of the statement passed to MySQL. Use the cursor to provide properly quoted parameters; don't try to generate the SQL string dynamically.

chepner Over a year ago

Notice I'm not using the Python % string operator; the %s are filled by the cursor using the tuple passed as a second argument to execute.

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