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Dynamic generation of images (was Re: Custom Classes?)

On Thu, 2008-05-08 at 10:33 -0500, Victor Subervi wrote:
Okay, trying this again with everything working and no ValueError or
any other errors, here we go:

Load this code. Unless you use a similar login() script, you will want
to edit your own values into the user, passwd, db and host:


import MySQLdb

import sys,os
sys.path.append (os.getcwd())
from login import login
user, passwd, db, host = login()

pic = "pic1"
w = 20
x = 0
d = 6
y = 1

getpic = "getpic" + str(w) + ".py"
os.remove(getpi c)
code = """
import cgitb; cgitb.enable()
import MySQLdb
import cgi
import sys,os
sys.path.append (os.getcwd())
from login import login
user, passwd, db, host = login()
form = cgi.FieldStorag e()
picid = int(form["id"].value)
x = int(form["x"].value)
pics =
{1:'pic1',2:'pi c1_thumb',3:'pi c2',4:'pic2_thu mb',5:'pic3',6: 'pic3_thumb',7: 'pic4',8:'pic4_ thumb',\
9:'pic5',10:'pi c5_thumb',11:'p ic6',12:'pic6_t humb'}
pic = pics[x]
db = MySQLdb.connect (host, user, passwd, db)
cursor= db.cursor()
sql = "select %s from products where id='%s';" % (pic, str(picid))

cursor.execute( sql)
content = cursor.fetchall ()[0][0].tostring()
print 'Content-Type: image/jpeg'
print content
script = open(getpic, "w")
script.write(co de)

and then surf to:
Also, please re-send the link on how to post good questions to the
list. I cannot find it.
Why are you dynamically creating getpic20.py?

Obviously, in the real script, you probably have several of them:
getpic1.py, getpic2.py, etc., but is there any reason you couldn't just
have one getpic.py, and pass the number in as a parameter in your GET
request, like this:


Then you can just have a static getpic.py. I've stripped out useless

* You don't use sys or os, so why import them?
* MySQL makes it difficult for me to replicate your behavior, because I
don't have your DB setup. The DB call has been replaced with a
dictionary of keys into JPG data, pulled from the filesystem. Change
filenames to jpegs on your own hard drive
* login is useless without MySQL.

So your new getpic.py (statically created) looks like this:

~~~ getpic.py ~~~

import cgitb; cgitb.enable()
import cgi

pics = {
1: open('pic.jpg') .read(),
2: open('pic2.jpg' ).read()
# you could just pass the filename, and then you wouldn't have to load
# image data in advance, but this more closely mimics the concept of
your DB
# setup.

form = cgi.FieldStorag e()
x = int(form["x"].value)
pic = pics[x]

print 'Content-Type: image/jpeg'
print pic

Then if you want to include your pictures in a web page, you do

~~~ show_pics.html ~~~
<head><title>Pi ctures</title></head>
<img src='http://example.com/getpic.py?x=1'/>
<img src='http://example.com/getpic.py?x=2'/>

This should work just as well when you refactor the script to pull from
the database.

Hope this helps. Also, the article on asking good questions is
available here: http://catb.org/~esr/faqs/smart-questions.html

Jun 27 '08 #1
0 874

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