ProgrammingError：字符串格式化过程中的参数数量错误

Question

I'm trying to put actively some datas from a list to my database in the table polls_ip . However it seems to be some problems of arguments maybe owing the type of the data I want to put inside.

If you want to have a look of the usefull part of my code:

fin_flag = ( tcp.flags & dpkt.tcp.TH_FIN ) != 0
rst_flag = ( tcp.flags & dpkt.tcp.TH_RST ) != 0

if fin_flag or rst_flag:
    src_ip2 = socket.inet_ntoa(ip.src)
    dst_ip2 = socket.inet_ntoa(ip.dst)
    for element in liste:
        if element == (src_ip2+" "+dst_ip2) or element == (dst_ip2+" "+src_ip2):
            liste.remove(element)

            cursor.execute("INSERT INTO polls_ip (Ip) VALUES (%s)", (element))

The problem probably come from the line inside cursor.execute Have a look at the output:

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "scriptbdd.py", line 134, in run
    self.p.dispatch(0, PieceRequestSniffer.cb)
  File "scriptbdd.py", line 120, in cb
    cursor.execute("INSERT INTO polls_ip (Ip) VALUES (%s)", (element))
  File "/usr/lib/pymodules/python2.7/mysql/connector/cursor.py", line 310, in execute
    "Wrong number of arguments during string formatting")
ProgrammingError: Wrong number of arguments during string formatting

And even with a coma in (element,)) , another problem is raised:

root@debian:/home/florian/Documents/mysite/polls# python scriptbdd.py 
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "scriptbdd.py", line 132, in run
    self.p.dispatch(0, PieceRequestSniffer.cb)
  File "scriptbdd.py", line 120, in cb
    cursor.execute("INSERT INTO polls_ip (Ip) VALUES (%s)", (element,))
  File "/usr/lib/pymodules/python2.7/mysql/connector/cursor.py", line 314, in execute
    res = self.db().protocol.cmd_query(stmt)
InterfaceError: Failed executing the operation; 'NoneType' object has no attribute 'cmd_query'

Answer 1

You forgot a comma:

cursor.execute("INSERT INTO polls_ip (Ip) VALUES (%s)", (element,))
#                                              add a comma here ^

That makes that second argument a tuple with one element, rather than just one value.

If you find it easier to work with, you could make that second argument a list rather than a tuple:

cursor.execute("INSERT INTO polls_ip (Ip) VALUES (%s)", [element])

Tuples are formed by using a comma (and parentheses are only really required when disambiguating those commas from other uses), while lists are formed by using the [..] syntax.

Your second error indicates your database connection has been closed; you cannot pass a cursor around if your database connection was stored in a local somewhere which has been cleaned up. For example, you cannot create a database connection in a function and only return the cursor; the local variable that references the connection would be cleaned up and the connection would close before you could use the cursor. See Why won't Python return my mysql-connector cursor from a function?