Step 01: Hello World with Deform¶

Many times you want forms generated for you. If you can live within the constraints, you gain a lot: slick widgets, automatic layout, validation, add and edit handling, and even Ajax submission.

Deform is a part of a set of Pylons libraries that break this functionality into its logically-separate parts:

Peppercorn for marshalling form data from requests
Colander for expressing constraints and fields as schemas
Deform for generating HTML form markup from a Colander schema, with built-in widgets and support for custom widgets

In this step we do the smallest possible step with Deform and Colander.

Goals¶

Hello world using Deform and Colander

Objectives¶

Add a static view for Deform’s static resources
Include those resources (CSS, JS) in the template’s <head>
Define a basic schema

Steps¶

easy_install deform
$ cd ../../forms_schema; mkdir step01; cd step01

Copy the following into step01/application.py:

from wsgiref.simple_server import make_server

from pyramid.config import Configurator


def main():
    config = Configurator()
    config.scan("views")
    config.add_static_view('deform_static', 'deform:static')
    app = config.make_wsgi_app()
    return app


if __name__ == '__main__':
    app = main()
    server = make_server(host='0.0.0.0', port=8080, app=app)
    server.serve_forever()

Copy the following into step01/views.py:

import colander
from deform import Form
from pyramid.view import view_config

class Person(colander.MappingSchema):
    name = colander.SchemaNode(colander.String())

class ProjectorViews(object):
    def __init__(self, request):
        self.request = request

    @view_config(renderer="templates/site_view.pt")
    def site_view(self):
        schema = Person()
        myform = Form(schema, buttons=('submit',))

        return {"form": myform.render()}

Copy the following into step01/templates/site_view.pt:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Projector</title>
    <link rel="stylesheet" href="/deform_static/css/form.css"
          type="text/css"
            />
    <script type="text/javascript"
            src="/deform_static/scripts/jquery-1.4.2.min.js"></script>
    <script type="text/javascript"
            src="/deform_static/scripts/deform.js"></script>
</head>
<body>
<h2>Hello Form</h2>

<div tal:content="structure form">form</div>
</body>
</html>

Copy the following into step01/tests.py:

import unittest

from pyramid.testing import DummyRequest

class ProjectorViewsUnitTests(unittest.TestCase):

    def _makeOne(self, request):
        from views import ProjectorViews
        inst = ProjectorViews(request)
        return inst

    def test_site_view(self):
        request = DummyRequest()
        inst = self._makeOne(request)
        result = inst.site_view()
        self.assertTrue('form' in result.keys())

class ProjectorFunctionalTests(unittest.TestCase):
    def setUp(self):
        from application import main
        app = main()
        from webtest import TestApp
        self.testapp = TestApp(app)

    def test_it(self):
        res = self.testapp.get('/', status=200)
        self.assertTrue('Hello Form' in res.body)

$ nosetests should report running 2 tests.
$ python application.py
Open http://127.0.0.1:8080/ in your browser.

Extra Credit¶

Read the Colander docs and allow the name field to be optionally missing without raising an validation warning.
Add an integer field.

Analysis¶

The application.py added a static view to the configuration for deform_static.

There is no real form hanlding being done. However, the form does do validation.

Discussion¶

Previous attempts at forms, and other form packages comparison and contrast
Reminder: Every choice on form libraries is doomed
Other ways to “discover” the path to the static views for deform

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