The error: names = curfetchone()[0]

TypeError: 'NoneType' object is not subscriptable. 

I tried checking the indentation but still there's an error. I read that maybe the variable names returns 'None' if there is no record of the filename in the database.

I use the same variable 'names' in other 'def' and it works fine. I'm sure it has to do with the 'None' value being returned.

global filename
global t
try:con = sqlite3.connect('textdb.db')cur = con.cursor()filename = tkinter.simpledialog.askstring("Open file...", "Input filename to open:")if filename != None:cur.execute("SELECT file_name FROM file_info WHERE file_name = ?", (filename,))names = cur.fetchone()[0]same = str(names)if filename == same:cur.execute("SELECT file_content FROM file_info WHERE file_name = ?", (filename,))content = cur.fetchone()[0]t = str(content)text.delete(0.0, END)text.insert(0.0, t)else:result = tkinter.messagebox.askyesno(title="File doesn't exist", message="'"+(filename)+"' doesn't exist. Make a new file using '"+(filename)+"'?")if result == True:cur.execute("SELECT COUNT(*) FROM file_info")count_row = cur.fetchone()cntdata = count_row[0]incr = (cntdata + 1)t = str(text.get(0.0, END))curtime = str(ctime())cur.execute("INSERT OR IGNORE INTO file_info VALUES(?, ?, ?, ?, ?)", (incr, filename, t, curtime, curtime,))con.commit()except sqlite3.Error:if con:con.rollback()
finally:if con:con.close()

If, due to whatever reason (empty result set?) curfetchone() returns None, a [0] access is of course forbidden (as the error message clearly says).

So better do that in two steps and do

row = curfetchone()
if row is not None: names = row[0]# proceed
else:# act appropriately