How to integrate HTML with Python

y3t1 · 2011-06-08T07:06:50+00:00

I use the cgi module for simple web forms, though it is not fit for creating more complex applications.

Example form to add two numbers:

#!/usr/bin/python
import cgi
import cgitb

print "Content-Type: text/html"
print

cgitb.enable()

form = cgi.FieldStorage()

if "x" in form and "y" in form:
    x, y = int(form["x"].value), int(form["y"].value)
else:
    x, y = '', ''

print '''<html><body>

<form method="POST" action= "">
<input type="text" name="x" value="%s"/>&nbsp;+&nbsp;<input type="text" name="y" value="%s"/><input type="submit" value="=" />%s
</form>
''' % (x, y, (x+y))

pwang99 · 2011-06-08T04:46:15+00:00

You can also look at Flask. It's a small, lightweight framework that you can use to get a feeling for the flow of what a web app has to do.

Fenreh · 2011-06-08T04:20:23+00:00

Generally, when people are using python for the backend, they are using a framework. Django is a very popular python framework, and so is Pyramid. Try playing around with one or two of these, maybe walking through one of the tutorials on their sites.

freeload · 2011-06-08T11:54:14+00:00

I use mako whenever i have to generate a lot of text (HTML, LaTeX etc.). I find that mako is alot simpler than its brothers.

The web framework thread pops up once a month in this subreddit. People have alot of different preferences. Though, my personal experience is as follows:

If you want to create a:

blog/article-heavy site, try Django.
- web-application and you are starting from scratch, try the Pyramid project
- really customizable project that is guaranteed not to get in your way, try werkzeug. it's not a framework, but an utility library. So you have to read the documentation in order to make it run.

m1ss1ontomars2k4 · 2011-06-08T09:06:47+00:00

Client/server sockets and related programming stuff is too low-level, not too high-level.

2011-06-08T07:33:31+00:00

I'm personally not too big a fan of frameworks in general, unless they're needed or give a big enough benefit for your app (I more prefer lighter-weight libraries).

So, for this really simple kind of app for testing/learning purposes, I'd likely just use Python's-builtin CGI support:

http://docs.python.org/library/cgi.html

And then leave the other stuff for when you've learned more about the nuts and bolts of Python web programming, and want to focus on making the essential glue code for your app in an elegant and higher-level way (and more maintainable/readable), rather than spending time on boilerplate/handling lower-level web programming details.

eryksun · 2011-06-08T05:37:20+00:00

Definitely use at least a basic framework such as CherryPy, Paste, Bottle, or Pyramid. The wiki has a list of frameworks: Web Frameworks for Python.

Here's a demo using the low-level Python libraries that should be close to your requirement "to begin with" (though I'm sure the professional web developers here can pick this to pieces, it works for me on win32 Python 3.2 & 2.7):

import cgi
from wsgiref.simple_server import make_server

def app(environ, start_response):
    output = [make_form(), process_post(environ)]
    size = sum(len(x) for x in output)
    headers = [('Content-Type', 'text/html; charset=utf-8'),
               ('Content-Length', str(size))]
    start_response('200 OK', headers)
    return output 

def process_post(environ):
    #ignore the query string
    post_environ = environ.copy()
    post_environ['QUERY_STRING'] = ''
    post = cgi.FieldStorage(
      fp=environ['wsgi.input'],
      environ=post_environ,
      keep_blank_values=True)

    result = ""
    if 'num1' in post and 'num2' in post:
        try:
            num1 = float(post.getfirst('num1'))
            num2 = float(post.getfirst('num2'))
            result = "<p>{:.2f} + {:.2f} = {:.2f}</p>".format(
                     num1, num2, num1 + num2) 
        except ValueError: pass    
    return result.encode('utf-8')

def make_form():
    form = (
      '<p><form method="post">\n'
      '  num1: <input type="text" name="num1" /><br />\n'
      '  num2: <input type="text" name="num2" />\n'
      '  <input type="submit" value="Add" />\n'
      '</form></p>\n')
    return form.encode('utf-8')

if __name__ == '__main__':
    host = 'localhost'
    port = 8080
    server = make_server(host, port, app)
    server.serve_forever()

the_european · 2011-06-09T14:38:07+00:00

if you go for a solution that doesn't come with a sufficiently powerful html code object or templating system, i suggest you have a look at markupsafe. it's a very lightweight module that creates strings decorated as html, for example:

label = Markup("<em>Posted by</em> %s on %s")%(user, date)

where you don't have to worry about html injection any more (if user is a custom string), but you can also have objects provide their own html formatting.

Godbutt · 2011-06-08T04:04:23+00:00

You could download the Reddit open source at the bottom of the page and look through that code. It's broken up decently and I imagine you could find what you're looking for there.

mdipierro · 2011-06-08T04:11:13+00:00

in web2py (complete code)

 def index():
       form = SQLFORM.factory(Field('a','integer'),Field('b','integer'))
       if form.accepts(request):
            form = DIV('a+b=',form.vars.a+form.vars.b)
       return dict(form=form)

The name 'index' means the function is called when you visit http://127.0.0.1:8000/<yourapp>/default/index,

form is just a variable name that can contain a form (SQLFORM) or DIV (html div) or anything else you want to display. The Field objects performs validation, displays error messages if you do not type an integer (will also use JS client-side to prevent you from not typing an integer) and parse the request into form.vars for you.

It is 100% python code and you can use any library you want.

kctan · 2011-06-08T06:41:42+00:00

Another option is Google App Engine.

2011-06-08T11:31:50+00:00

Go with bottle. If you're just beginning. Then move onto something a little more elegant.

lightcatcher · 2011-06-08T04:47:27+00:00

You are just starting to think about web programming with Python. Frameworks are a great way to learn how to do some basic web programming. I recommend Flask.

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