web2py:Web development like a boss

Web2py:
Web development like a boss
Francisco Gama Tabanez Ribeiro

Agenda
‣ my path on web dev - lessons learned
‣ web2py web framework:
‣ intro
‣ internals
‣ live demo - building a WiKi
‣ resources

PHP?
Python is well designed, PHP is not:
Although it’s perfectly possible to write good
code in PHP,
it’s much easier to write great code in Python
from Why PHP Is Fun and Easy But Python Is Marriage
Material

Perl?
• LUKE: Is Perl better than Python?
• YODA: No... no... no. Quicker, easier, more seductive.
• LUKE: But how will I know why Python is better than Perl?
• YODA:You will know. . .
When your code you try to read six months from now.

Ruby?
Beautiful is better than ugly.
[...]
Although practicality beats purity.
from The Zen of Python

lessons learned (1/2)
• rapid turnaround
• secure by design
• web development is mostly about visual UI’s
• relies mostly on user interaction & feedback
• convention over conﬁguration
• ﬂexible as in hackable

lessons learned (2/2)
• fast and efﬁcient but mostly scalable and stable
• different things come in different places
• plays well with others
• backward compatibility assured
• live community & support resources
• fun

Welcome to the club!
founder: Massimo Di Pierro
main contributors: +80
users: +2000

Install and run...
curl -O http://www.web2py.com/examples/static/web2py_src.zip

why?
• easy to run, install and play with
• python based
• web IDE included
• web based database admin
• no dependencies, no conﬁguration required
• multiple platform (GAE, EC2, Jython...)

why?
• Open source (LGPLv3 license)
• web2py applications have no license constraints
• web2py allows application bytecode compilation
• always backward compatible
• deployment-friendly...

deployment..
• always backward
compatible
• integrates well with web
servers (cgi, fcgi,
mod_python, mod_wsgi)
• error logging and
ticketing support
• Database Abstraction
Layer integrated
• integrated versioning
• integrated self-update
capability
• multiple caching
methods
• testing methods and
debug shell

what else?
• secure (against XSS, Injection ﬂaws, RFI)
• SSL and multiple authentication methods
• enforces good Software Engineering practices (MVC,
Server-side form validation, postbacks...)
• Internationalization support
• HTML/XML, RSS/ATOM, RTF, PDF, JSON, AJAX
(includes jQuery), XML-RPC, CSV, REST, WIKI, Flash/
AMF, and Linked Data (RDF)

Hello World
def hello1():
return "Hello World"
controllers/simple_examples.py

Olá Mundo
(Translation)
def hello2():
return T("Hello World")

Controller-View
def hello3():
return dict(message=T("Hello World"))
{{extend 'layout.html'}}
<h1>{{=message}}</h1>
views/hello3.html

View
<html>
<head>
<title>example</title>
</head>
<body>
{{include}}
</body>
</html>
views/
views/hello3.html

Web2py: inside
Python
rocket
(SSL enabled web server)
API for third party servers
(Apache,...)

Web2py: inside
Python
rocket
(Apache,...)
Core libraries
(HTTP request/response, session,
auth, services, DAL,...)
Contrib
(simplejson, markdown,
memcache, pyrtf, rss,...)

Web2py: inside
Python
rocket
(Apache,...)
Core libraries
(HTTP request/response, session,
auth, services, DAL,...)
User Applications
admin welcome user app
Contrib
(simplejson, markdown,
memcache, pyrtf, rss,...)
examples

web2py app inside
models
controllers
views
translations
static data
plugins & modules
appadmin
data

models
controllers
views
translations
static data
plugins & modules
appadmin
data
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
db = SQLDB(‘sqlite://data.db’)
db.deﬁne_table(‘category’,
Field(‘name’))
db.deﬁne_table(‘recipe’,
Field(‘title’),
Field(‘category’,db.category),
Field(‘description’,‘text’))
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
Field(‘name’))
Field(‘title’),
SQlite
MySQL
PostgreSQL
Oracle
MSSQL
DB2
Firebird
MyBase
Informix
Google App Engine
Database types:
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
Field(‘name’))
Field(‘title’),
string
text
integer
double
date
datetime
time
boolean
password
upload
blob
reference
list:string
list:interger
list:reference
Field types:
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
Field(‘name’))
Field(‘title’),
db.recipe.title.requires=IS_NOT_EMPTY()
db.recipe.category.requires=IS_IN_DB(db,'category.id','category.name')
db.category.name.requires=IS_NOT_IN_DB(db,'category.name')
db.recipe.description.default='Fill your recipe in here...'
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
Field(‘name’))
Field(‘title’),
db.recipe.title.requires=IS_NOT_EMPTY()
db.recipe.category.requires=IS_IN_DB(db,'category.id','category.name')
db.category.name.requires=IS_NOT_IN_DB(db,'category.name')
db.recipe.description.default='Fill your recipe in here...'
IS_DATE
IS_DATETIME
IS_DATETIME_IN_RANGE
IS_DATE_IN_RANGE
IS_DECIMAL_IN_RANGE
IS_EMAIL
IS_EMPTY_OR
IS_EQUAL_TO
IS_EXPR
IS_FLOAT_IN_RANGE
IS_GENERIC_URL
IS_HTTP_URL
IS_IMAGE
IS_INT_IN_RANGE
IS_IN_DB
IS_IN_SET
IS_IN_SUBSET
IS_IPV4
IS_LENGTH
IS_LIST_OF
IS_LOWER
IS_MATCH
IS_NOT_EMPTY
IS_NOT_IN_DB
IS_NULL_OR
IS_SLUG
IS_STRONG
IS_TIME
IS_UPLOAD_FILENAME
IS_UPPER
IS_URL
IS_ALPHANUMERIC
Validators:
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
def index():
return dict(recipes=db().select(db.recipe.ALL))
def add():
form=SQLFORM(db.recipe)
if form.accepts(request.vars):
redirect(URL(r=request,f='index'))
return dict(form=form)
def show():
recipes=db(db.recipe.id==request.args[0]).select()
if not len(recipes):
redirect(URL(r=request,f='index'))
return dict(recipe=recipes[0])
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
in file views/default/add.html:
<h1>{{T(‘New recipe’)}}</h1>
{{=form}}
in file views/default/index.html:
<h1> {{T(‘List all recipes’)}} </h1>
<table>
{{for recipe in recipes:}}
<tr><td>{{=A(T(recipe.title),_href=URL(r=request,f='sh
ow', args=recipe.id))}}</td></tr>
{{pass}}
</table>
in file views/default/show.html:
<h1> {{=T(recipe.title)}}
{{=db.recipe.category.represent(recipe.category)}}
</h1>
<pre> {{=recipe.description}}</pre>
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
T(‘New recipe’)
T(‘List all recipes’)
T(recipe.title)
‘Nova receita’
‘Nouvelle receité’
...
‘Listar receitas’
‘Lister receité’
...
‘bitoque’
‘duple cliché’
...
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
images
css
js
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
ways to extend your apps:
• modules are good way to import external
code
• plugins are applications subsets - a small
application “inside” your application
web2py app inside

models
controllers
views
translations
static data
plugins & modules
appadmin
data
web2py app inside
• databases (SQlite, MySQL, PostgreSQL,
Oracle, MSSQL, DB2, Firebird, MyBase,
Informix, Google App Engine)
• metadata for automatic migrations
• cache

models
controllers
views
translations
static data
plugins & modules
appadmin
data
default web based interface to your data
web2py app inside

web2py URL parsing
http://www.myhost.com:8000/myapp/default/index.html/a/b/c?name=Max
request.application = “myapp”
request.controller = “default”
request.function = “index”
request.extension = “html”
request.args = [‘a’,’b’,’c’]
request.vars.name = “Max”
Environment variables
are in request.env
equivalent to
request.vars[‘name’]

• functions in controllers return dicts() into views
• controller methods are exposed to views with the
same name which is also used in the URL
• input validators (forms) are deﬁned in the model as
integrity constraints (requires)
• DAL automatically creates the id ﬁeld in your tables
• model code has full application scope
remember..

remember..
• you can use your editor of choice
• you can use DAL separately
• in controller functions you can redeﬁne the target
view with response.view=”theme/myview.html”
• web2py shell is your friend
• recommended - start your ﬁles with:
# coding: utf8

sessions
<html>
<head></head>
<body>
<h2>Number of visits: {{=counter}}</h2>
</body>
</html>
def index():
session.counter = (session.counter or 0) + 1
return dict(message="Hello from MyApp", counter=session.counter)
inside controller:
inside view:

DAL select()
db(query).select(
field1, field2, ...,
left=[db.table.on(query)],
orderby=field|~field,
groupby=field|field
limitby=(0,10),
cache=(cache.ram,5000))
Examples:
rows = db(db.recipe).select()
rows = db(db.recipe.id>0).select(
db.recipe.title, db.recipe.category,
orderby = db.recipe.category,
distinct=True)
# christmas recipes from 2000
query1 = db.recipe.created_in.year()>2000
query2 = db.recipe_created_in.month()<10
rows = db(query1 & query2).select()

DAL select()
db(query).select(
limitby=(0,10),
Examples:
distinct=True)
equivalent to:
rows = db(db.recipe.id>0).select(db.recipe.ALL)

DAL select()
db(query).select(
limitby=(0,10),
Examples:
distinct=True)
equivalent to:
rows = db(db.recipe.id>0).select(db.recipe.ALL)
queries can be combined with and(&), or(|) and not(~)

DAL operations
• Insert:
db.category.insert(name=‘soup’)
• Update:
db(db.category.name==‘soup’).update(name=‘french soups’)
• Delete:
db(db.category.name==‘french soups’).delete()
• Count:
db(db.category.name.like(‘%soup%’)).count()

DAL operations
• Insert:
• Update:
• Delete:
• Count:
Other operators:
.max(), .min(), .sum(), .bel
ongs(), .like(),...

DAL operations
• Insert:
• Update:
• Delete:
• Count:
Other operations:
transactions, inner joins, left outer joins, nested selects, self-references, many2many, ...
Other operators:
.max(), .min(), .sum(), .bel
ongs(), .like(),...

Forms
• SQLFORM() / SQLFORM.factory()
• FORM()
• CRUD()
• <form></form>

HTML helpers (form)
def display_form():
form=FORM('Your name:',
INPUT(_name='name', requires=IS_NOT_EMPTY()),
INPUT(_type='submit'))
if form.accepts(request.vars, session):
response.flash = form.vars.name +', thank you'
elif form.errors:
response.flash = 'form has errors'
else:
response.flash = 'please fill the form'
return dict(form=form)
...
<div class="flash">{{=response.flash or ''}}</div>
{{=form}}
...
inside controller:
inside view:

Components
LOAD()
{{=LOAD(‘controller’,‘function’, ajax=True)}}

Components
LOAD()
{{=LOAD(‘controller’,‘function’, ajax=True)}}
supports auth signatures

web2py Shell
python web2py.py -S myapplication -M

HTML helpers
• BEAUTIFY(whatever)
• URL('application', 'controller', 'function',
args=['x', 'y'], vars=dict(z='t'))
• much more... /application/controller/function/x/y?z=t

Authentication &
Authorization (Role-based)

Authentication &
doc_id = db.document.insert(body = 'top secret')
agents = auth.add_group(role = 'Secret Agent')
auth.add_membership(agents, james_bond)
auth.add_permission(agents, 'read', secrets)
auth.has_permission('read', secrets, doc_id, james_bond)
auth.has_permission('update', secrets, doc_id, james_bond)
auth.is_logged_in()

Authentication &
@auth.requires_login()
@auth.requires_membership(agents)
@auth.requires_permission('read', secrets)
@auth.requires_permission('delete', 'any ﬁle')
@auth.requires(auth.user_id==1 or request.client=='127.0.0.1')
@auth.requires_permission('add', 'number')
you also have:
agents = auth.add_group(role = 'Secret Agent')
auth.add_membership(agents, james_bond)
auth.add_permission(agents, 'read', secrets)

@service.csv
@service.rss
@service.xml
def list_recipes():
return db(db.recipe).select()
@service.run
@service.csv
@service.rss
@service.json
@service.jsonrpc
@service.xml
@service.xmlrpc
@service.soap
@service.amfrpc3('domain')
Services
http://myhost/application/controller/list_recipes.xml

@service.csv
@service.rss
@service.xml
def list_recipes():
return db(db.recipe).select()
@service.run
@service.csv
@service.rss
@service.json
@service.jsonrpc
@service.xml
@service.xmlrpc
@service.soap
@service.amfrpc3('domain')
Services
http://myhost/application/controller/list_recipes.xml
.csv
...
.json

Errors (ticketing)
errors/exceptions are logged into tickets

Other
• Cron
• Routes
• Plugins
• Modules
• Grids
Caching in functions:
@cache("key",cache.ram,5000)
def f(): return dict()
Caching actions/views:
@cache(request.env.path_info,5000,cache.ram)
def action():
return response.render(response.view,dict())
could be:
cache.ram, cache.disk, cache.memcache

demoWiKi app
(features)
• add pages
• show pages
• edit pages
• versioning
• authentication
(local and remote)
• internationalization
• comments
(with/without AJAX)

web2py in real life
Francisco Costa

Documentation (1/2)
• online book (www.web2py.com/book)
• book (printed version - amzn.to/vzjiqT)
• screencasts (www.vimeo.com)
• interactive examples (default app)
• AlterEgo (FAQ - www.web2py.com/AlterEgo)

Documentation (2/2)
• epydoc
(www.web2py.com/examples/static/epydoc/)
• API:
(www.web2py.com/book/default/chapter/
04#API)

Community (1/2)
• free web2py appliances
(www.web2py.com/appliances)
• code snippets (www.web2pyslices.com)
• groups:
• users - http://groups.google.com/group/web2py/
• developers - http://groups.google.com/group/web2py-developers

Community (2/2)
• #web2py (IRC channel at irc.freenode.net)
• twitter (http://twitter.com/web2py)
• user voice (http://web2py.uservoice.com)
• web2py websites (www.web2py.com/
poweredby)
• web2py plugins (www.web2py.com/plugins/)

Thank you
childish wont-let-go nickname: blackthorne
blackthorne (geek)
bthorne_daily (social)
francisco@ironik.org
(PGP key: 0xBDD20CF1)
http://www.digitalloft.org
(homepage)

web2py app defaults
• menu
• web2py_ajax (jQuery)
• auth, mail, download and services
• english default lang translation
• generic view

web2py:Web development like a boss

Recommended

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to web2py:Web development like a boss (20)

Recently uploaded (20)

web2py:Web development like a boss