Posts tagged Python

I coded a basic captcha for my web.py form, here’s how:

First I made a function that generates an image and returns it + the code (yea yea it’s a mess).

import Image, ImageDraw, ImageFont, cStringIO, random

def getCaptcha():
    im = Image.new("RGB", (100, 60))
    draw = ImageDraw.Draw(im)
    
    for x in range(0, 100):
        for y in range(0, 60):
            draw.point((x, y), (135, 191, 107))
        
    font = ImageFont.truetype('cracked.ttf', 50)

    alphabet = 'abcdefghijklmnopqrstuvwxyz'

    word = ''
    for i in range(5):
        word = word + alphabet[random.randint(0, len(alphabet) -1)]

    draw.text((5, 5), word, font=font, fill=(0, 0, 0))
    
    f = cStringIO.StringIO()
    im.save(f, "GIF")
    f.seek(0)
    return word, f

Now here’s snippets of web.py code:

urls = (
    ...
    '/captcha.gif', 'captcha'
)

if web.config.get('_session') is None:
    session = web.session.Session(app, web.session.DiskStore('sessions'), initializer={'captcha': ''})
    web.config._session = session
else:
    session = web.config._session

vcaptcha = form.Validator('Please enter the code',  lambda x:x == session.captcha)

enquiry_form = form.Form( 
    ...
    form.Textbox("captcha", vcaptcha, description="Validation Code", pre="<img src='/captcha.gif' valign=center><br>", class_="standard", style="width:70px;"),
)

class captcha:
    def GET(self):
        web.header("Content-Type", "image/gif")
        captcha = getCaptcha()
        session.captcha = captcha[0]
        return captcha[1].read()

Also to make the form look prettier I modified web.py to give the table rows an id and then used css to alter their padding etc.

Sorry I didn’t take much time over this post, hopefully the code will get you started though, Dave.

If you want to follow the web.py tutorial using sqlite here’s how:

Line for your python to connect to DB

db = web.database(dbn='sqlite', db='testdb')

To create the database type

sqlite3 testdb

and input this SQL:

CREATE TABLE todo (id integer primary key, title text, created date, done boolean default 'f');
CREATE TRIGGER insert_todo_created after insert on todo
begin
update todo set created = datetime('now')
where rowid = new.rowid;
end;

Now create an entry with this SQL

insert into todo (title) values ('Learn web.py');

Finally quit sqlite3 when your ready by typing

.quit

So I decided to learn Python and Django in the hopes it would be a half way house between PHP and Lisp, letting me actually get stuff done whilst not being PHP.

My first impression of Django has been pretty bad, I bought the ‘definitive guide’ book only to find it was not so much definitive as obsolete. Also the amount of arbritary seeming magic didn’t impress. Having said that I have passed through that and I’m beginning to get the hang of it.

Python on the other hand was different, to start with I HATED the look of the code compared to Lisp but after a few hours hacking it doesn’t seem that bad. For my first program I decided to solve this little puzzle. This great guide got me going quickly and along with a few small pointers from verte in the friendly seeming #python I came to a solution.

def draw_diamond(letter):
    alphabet = 'abcdefghijklmnopqrstuvqxyz'
    size = alphabet.find(letter)

    for x in range(size) + range(size, -1, -1): 
        line = [' '] * ((2 * size) + 1)
        line[size + x] = alphabet[x]
        line[size - x] = alphabet[x]
        print "".join(line)

draw_diamond('d')

It didn’t take long, the code looks nice and most importantly I enjoyed writing it. I’m pretty impressed!