How to use forms

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Problem

How to use forms.

Solution

The web.form module provides support for creating, validating, and rendering forms. This module contains a Form class and classes for various inputs like Textbox, Password etc.

Each input can take a list of validators as arguments which are validated against the input when form.validates() is called.

The Form class can take additional keyword argument validators to validate the form using complete input.

Here is an example of a new user registration form:

import web
from web import form

render = web.template.render('templates') # your templates

vpass = form.regexp(r".{3,20}$", 'must be between 3 and 20 characters')
vemail = form.regexp(r".*@.*", "must be a valid email address")

register_form = form.Form(
    form.Textbox("username", description="Username"),
    form.Textbox("email", vemail, description="E-Mail"),
    form.Password("password", vpass, description="Password"),
    form.Password("password2", description="Repeat password"),
    form.Button("submit", type="submit", description="Register"),
    validators = [
        form.Validator("Passwords did't match", lambda i: i.password == i.password2)]

)

class register:
    def GET(self):
        # do $:f.render() in the template
        f = register_form()
        return render.register(f)

    def POST(self):
        f = register_form()
        if not f.validates():
            return render.register(f)
        else:
            # do whatever is required for registration

And the register template should be something like this:

$def with(form)

<h1>Register</h1>
<form method="POST">
    $:form.render()
</form>