datetime objects format

You can convert them to strings and simply pad them:

import datetime

d = datetime.datetime(2012, 5, 25)

m = str(d.month).rjust(2, '0')
print(m) # Outputs "05"

Or you could just a str.format:

import datetime

d = datetime.datetime(2012, 5, 25)

print("{:0>2}".format(d.month))

EDIT: To answer the updated question, have you tried this?

import datetime
d = datetime.datetime(2012, 5, 25)
print("{:0>4}-{:0>2}-{:0>2}".format(d.year, d.month, d.day))

You said you were originally printing them using string formatting, so what did you change? This code:

print "%s-%s-%s"%(date.year, date.month, date.day, etc., len(str) )

Doesn't really make any sense, since I'm a little unclear as to what arguments you are passing in. I assume just date.year, date.month, and date.day, but it's unclear. What action are you performing with len(str)?

zfill is easier to remember:

In [19]: str(dt.month).zfill(2)
Out[19]: '07'

You can print the individual attributes using string formatting:

print ('%02d' % (mydate.month))

Or more recent string formatting (introduced in python 2.6):

print ('{0:02d}'.format(a.month))  # python 2.7+ -- '{:02d}' will work

Note that even:

print ('{0:%m}'.format(a))  # python 2.7+ -- '{:%m}' will work.

will work.

or alternatively using the strftime method of datetime objects:

print (mydate.strftime('%m'))

And just for the sake of completeness:

print (mydate.strftime('%Y-%m-%d')) 

will nicely replace the code in your edit.