Why doesn't this work (sqlite, python)

Question

I tried to do this in the interpreter and I can get it to work but inside my function it doesn't

What I'm trying to do:

cursor = dbconnect.cursor()
cursor.execute("""SELECT * FROM credits WHERE phone = ?""",(phone,))
data = cursor.fetchone()
firstname = data[1] #the db is set as firstname in position 1 after the id(primekey)

I'm actually extracting all the data using this method just with different variables

The Error I get when I do it inside the function:

firstname = data[1]  
TypeError: 'NoneType' object is not subscriptable

As a note: I put a print statement after the data object to see what it was returning, in the interpreter it returns the tuple i'm searching for, inside the function it's returning 'None'

FULL CODE:

def FindByPhone(self,phone): 
    '''Find Credit by phone number ONLY'''    
    dbconnect = sqlite3.connect(self.dbname)  
    cursor = dbconnect.cursor()  
    cursor.execute("""SELECT * FROM credits WHERE phone = ?""",(phone,))  
    data = cursor.fetchone()  
    first = data[1]  
    last = data[2]  
    phone = data[3]  
    credit = data[4]  
    cid = data[0]
    self.SetVariables(first,last,phone,credit,cid)
    cursor.close()
    dbconnect.close()
    return

Gryphius · Accepted Answer · 2011-06-08 06:34:45Z

2

I think the problem is that your function doesn't check if there was a matching row in the database. you will get this error if no row is being returned:

#!/usr/bin/python
try:
    import sqlite3
except:
    from pysqlite2 import dbapi2 as sqlite3

#prepare testcase    
db="/tmp/soverflow.sqlite"
dbconnect = sqlite3.connect(db)
c = dbconnect.cursor()
c.execute("""create table credits
(id int not null primary key, firstname varchar(50), phone varchar(30),amount int not null)""")
c.execute("""INSERT INTO credits (id,firstname,phone,amount) VALUES (1,'guybrush','123-456',24)""")
c.execute("""INSERT INTO credits (id,firstname, phone,amount) VALUES (2,'elaine','1337-1337',18)""")
dbconnect.commit()
c.close()


def print_firstname(phone):
    cursor = dbconnect.cursor()
    cursor.execute("""SELECT * FROM credits WHERE phone = ?""",(phone,))
    data = cursor.fetchone()
    firstname = data[1]
    cursor.close() # cleanup
    print firstname

print "testing existing row"
print_firstname('1337-1337')

print "testing missing row"
print_firstname('nothere')

=>

./soverflow_sqlite.py 
testing existing row
elaine
testing missing row
Traceback (most recent call last):
  File "./soverflow_sqlite.py", line 31, in <module>
    print_firstname('not-in-db')
  File "./soverflow_sqlite.py", line 23, in print_firstname
    firstname = data[1]
TypeError: 'NoneType' object is not subscriptable

Solution: Add a check if there was a row returned from your query

edited Jun 8, 2011 at 6:34

answered Jun 8, 2011 at 6:29

Gryphius

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5 Comments

Isov5 Over a year ago

I just added the actual code im trying to run in my original post

Gryphius Over a year ago

how exactly do you call your function? maybe the phone value itself is None or a value that doesn't exist in the db?

Isov5 Over a year ago

Well i'm calling it from the GUI wx.TextCtrl that I'm setting to a variable... something like phone = wx.TextCtrl.GetValue()

Gryphius Over a year ago

print out the phone value in the function itself and check if it really contains what you expect.

Isov5 Over a year ago

It was returning None...but THANKS anyhow because of me doing that I found out I never called the function that set the phone variable...Therefore that's the reason it was returning None!

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