Web Development with Python and Django
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The document is a comprehensive guide on web development using Python and Django, covering topics such as project setup, creating apps, building views and templates, handling forms, and managing user authentication. It emphasizes Django's features like ORM, middleware, and template inheritance while providing code examples and exercises. The guide also discusses best practices for environment setup, package management, and code organization.
![String Operations
"foo" + "bar"
"foo"[0]
"foo"[:1]
"foo".upper()
"{0}: {1}".format("foo", "bar")
"{foo}: {bar}".format(foo=42, bar=1138)
len("foo")](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-17-320.jpg)
![Lists, Tuples, and Sets
['a', 'b', 'c']
('Rush', '2112', 5.0)
set(['a', 'b', 'c'])](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-19-320.jpg)
![Sequence Operations
[...][0]
[...][-1]
[...][:1] # same as [...][0:1]
[...].append(4)
[...].extend([4, 5, 6])
[...].pop()
len([...])](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-20-320.jpg)
![Dictionary Operations
{...}['key1']
{...}.get('key2', default)
{...}.keys()
{...}.values()
{...}.items()
len({...})](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-22-320.jpg)
![Introspection
>>> dir(Foo)
['__class__', '__delattr__', '__dict__', '__doc__',
'__format__', '__getattribute__', '__hash__',
'__init__', '__module__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__setattr__',
'__sizeof__', '__str__', '__subclasshook__',
'__weakref__']](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-33-320.jpg)
![Using a Form in a View
from myapp.forms import MyForm
def my_view(request):
form = MyForm(request.POST or None)
if request.method == "POST" and form.is_valid():
name = form.cleaned_data['name']
email = form.cleaned_data['email']
# do something great with that data
return render(request, 'myapp/myform.html', {
'form': form
Framework
})
Middleware
URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-76-320.jpg)
![Sending Mail
• Add an EMAIL_BACKEND in settings.py
EMAIL_BACKEND =
'django.core.mail.backends.console.EmailBackend'
• Import and use
from django.core.mail import send_mail
send_mail('subject', 'message', 'sender',
['recipient', ...]) Framework
Middleware
URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-79-320.jpg)
![Login Aer Registration
from django.contrib.auth import authenticate, login
user = authenticate(
username=form.cleaned_data['username'],
password=form.cleaned_data['password1'])
login(request, user)
Framework
Middleware
URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-98-320.jpg)
![Saving a Model Object
thingy = Thingy()
thingy.size = 'big'
thingy.save()
gadget = Gadget(thingy=thingy)
gadget.save()
gizmo = Gizmo(thingies=[thingy])
gizmo.save()
Framework
Middleware
URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-134-320.jpg)
![Generic Edit Views
from django.shortcuts import resolve_url
from django.view.generic.edit import UpdateView
from myapp.forms import ThingyForm
class ThingyUpdateView(UpdateView):
form_class = ThingyForm
queryset = Thingy.objects.all()
def get_success_url(self):
return resolve_url('myapp:thingy')
def get_context_data(self, **kwargs): Framework
context = super(ThingyUpdateView, self).get_context_data(**kwargs)
context['editing'] = True Middleware
return context URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-163-320.jpg)
![Generic Edit View URLs
from django.conf.urls import patterns, include, url
from myapp.views import ThingyUpdateView
urlpatterns = patterns('myapp.views',
...
url(r'(?P<pk>[0-9]+)$', ThingyUpdateView.as_view(),
name='update'),
)
Framework
Middleware
URLs
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-164-320.jpg)
![Exercise 20
• Create a custom filter function
“boolean_icon” that will show one image if
a value is True and another if it’s False
• Use the boolean_icon in the user’s profile to
indicate whether a talk has been approved
• Use static icons from the admin site: Framework
from django.contrib.admin.templatetags.admin_static import static
Middleware
icon_url = static('admin/img/icon-{0}.gif'.format( URLs
{True: 'yes', False: 'no', None: 'unknown'}[value])
Views
Tem-
Models
plates
Tags &
DB
Filters](https://image.slidesharecdn.com/djangoprecompiler-130113213208-phpapp02/85/Web-Development-with-Python-and-Django-181-320.jpg)
Web Development with Python and Django
- 1. Web Development with Python and Django Mike Crute • Mike Pirnat • David Stanek
- 2. Today • Iteratively build a full-featured site • Background for each feature • Implement a feature • Review our example solution • Keep yours? git show tag • Follow directly? git reset --hard tag
- 3. Useful Links • http://docs.python.org • https://docs.djangoproject.com • https://github.com/finiteloopsoware/ django-precompiler/wiki
- 4. Let’s Have a Show of Hands...
- 5. Django
- 6. Django?
- 7. Django
- 8. Django • A high-level Python web framework • Encourages rapid development and clean, pragmatic design • “For perfectionists with deadlines” • Focus on automation and DRY • Widely supported, many deployment options
- 9. Perhaps You’ve Heard Of... • Disqus • Pinterest • Instagram • PolitiFact.com • Mozilla • Rdio • OpenStack
- 10. Django • ORM • Cache infrastructure • Automatic admin • Internationalization interface • Command-line job • Regex-based URL design framework • Templating system
- 12. Python is... • Dynamic • Exceptional • Interpreted • Comfortable • Duck-Typed • Readable • Object-Oriented • Opinionated • Functional • Batteries Included • Strongly-Namespaced • Community
- 13. Interactive Shell $ python >>> print "Hello, world!" Hello, world! >>> $ python3 >>> print("Hello, world!") Hello, world! >>>
- 14. Comments # Best. Code. Evar.
- 17. String Operations "foo" + "bar" "foo"[0] "foo"[:1] "foo".upper() "{0}: {1}".format("foo", "bar") "{foo}: {bar}".format(foo=42, bar=1138) len("foo")
- 19. Lists, Tuples, and Sets ['a', 'b', 'c'] ('Rush', '2112', 5.0) set(['a', 'b', 'c'])
- 20. Sequence Operations [...][0] [...][-1] [...][:1] # same as [...][0:1] [...].append(4) [...].extend([4, 5, 6]) [...].pop() len([...])
- 21. Dictionaries {'key1': 'value1', 'key2': 'value2'}
- 23. Assignment & Comparison foo = 'bar' foo == 'baz' foo != 'baz' foo is None foo is not None
- 24. Flow Control if expression: ... elif expression: ... else: ...
- 25. Flow Control for item in sequence: if expression: continue if expression: break
- 26. Flow Control while expression: if expression: continue if expression: break
- 27. Functions def foo(): return 42 def foo(bar): return bar def foo(bar, baz='quux'): return (bar, baz) def foo(*args, **kwargs): return (args, kwargs)
- 28. Decorators @bar def foo(): return 42 @baz('xyzzy') def quux(): return 42
- 29. Classes class Foo(object): def __init__(self, bar): self.bar = bar
- 30. Docstrings "Modules can have docstrings." class Foo(object): "Classes can have docstrings too." def __init__(self, bar): "So can functions/methods."
- 31. Exceptions try: raise Exception("OH NOES!") except: log_error() raise else: do_some_more() finally: clean_up()
- 32. Namespaces import logging from datetime import timedelta from decimal import Decimal as D
- 33. Introspection >>> dir(Foo) ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']
- 34. Introspection >>> help(Foo) Help on class Foo in module __main__: class Foo(__builtin__.object) | Classes can have docstrings too. | | Methods defined here: | | __init__(self, bar) | So can functions/methods. | ... -------------------------------------------------------- | Data descriptors defined here:
- 35. And more... • Generators • Properties • Generator Expressions • Context Managers • List Comprehensions • Class Decorators • Set Comprehensions • Abstract Base Classes • Dictionary • Metaclasses Comprehensions
- 36. Style: PEP-8 • No tabs • Line breaks around 78-79 chars • Four-space indents • Some other OCD- • Don’t mix tabs & spaces pleasing ideas :-) • lower_case_methods • CamelCaseClasses
- 37. Setup
- 38. Environment Setup • Mac or Linux? You’ve already got Python! • You’ll also need Git if you don’t have it; download it from http://git-scm.com or use your package manager to install it • Windows? Well, then...
- 39. Windows Setup • Portable Python and Portable Git • Won’t modify your system at all • Can be easily uninstalled • If you want to permanently install Python and Git you can easily do that too
- 40. Portable Python 2.7 • Download http://bit.ly/13eyQGn http://p.osuosl.org/pub/portablepython/v2.7/PortablePython_2.7.3.1.exe • Run the .EXE • Install into c:django-precompiler • Download won't work? p://p.codemash.org/webdev_with_django
- 41. Portable Git • Download http://bit.ly/X4dGps http://msysgit.googlecode.com/files/Git-1.8.0-preview20121022.exe • Create a new folder • Extract archive into a new folder: c:django-precompilerPortable Git 1.8.0-preview20121022 • Download won't work? p://p.codemash.org/webdev_with_django
- 42. Fixing the Path • Download: https://gist.github.com/4399659 • Save it as a file named run-cmd.bat • Run it • Download won't work? p://p.codemash.org/webdev_with_django
- 43. Installing Packages • easy_install: easy_install package • pip: pip install package
- 44. Installing Packages • Installed packages go into a site-packages directory in your Python lib • That’s the “system Python” by default • But different programs may need different versions of packages... • So we have virtual environments!
- 45. Virtual Environments • virtualenv • Creates an isolated Python environment with its own site-packages • Install whatever you want without fouling anything else up
- 46. Python 2 or 3? • The future of Python is Python 3 • Django 1.5 has experimental Python 3 support • Python 2.7 is still recommended for production applications • Django 1.6 will fully support Python 3
- 47. Activate the Virtual Environment # Mac/Linux/etc... $ virtualenv django-precompiler $ cd django-precompiler $ source bin/activate # Windows > python virtualenv django-precompiler > cd django-precompiler > Scripts/activate.bat
- 48. The Django Stack
- 49. Request Django Response
- 50. Request Framework Middleware Django URLs Response Views Models Templates Tags & DB Filters
- 51. The Project...
- 52. CODE SMASH! • Code Smash is a fictional soware development conference for people who need to punch out awesome code • It needs a website! • We’re going to build one
- 53. Starting a Project # Normally... $ git init src # Today... $ git clone https://github.com/finiteloopsoftware/ django-precompiler.git src $ cd src $ git reset --hard ex00
- 54. Defining Requirements • requirements.txt • A basic example: MyApp Framework==0.9.4 Library>=0.2 http://someserver.org/packages/MyPackage-3.0.tar.gz
- 55. Requirements • Create a requirements.txt • Require Django version 1.5; use: https://www.djangoproject.com/download/1.5c1/tarball/
- 56. Installing Requirements $ pip install -r requirements.txt
- 57. Starting a Project # Mac/Linux/etc. $ django-admin.py startproject codesmash ./ $ python manage.py runserver # Windows > python Scripts/django-admin.py startproject codesmash > python manage.py runserver
- 58. New Project Contents src/ codesmash/ __init__.py settings.py urls.py wsgi.py manage.py
- 59. A Static Home Page
- 60. Templates • Make a templates directory under src: $ mkdir templates • Update settings to tell Django where to find the templates • Put an HTML file in the templates directory Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 61. URLs • Map URLs in requests to code that can be executed • Regular expressions! • Subsections of your site can have their own urls.py modules (more on this later) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 62. URLs from django.conf.urls import patterns, include, url urlpatterns = patterns('', url(r'^$', 'codesmash.views.home', name='home'), )
- 63. Views • Code that handles requests • Other frameworks oen call these “controllers” • Basically a function that: • gets a request passed to it • returns text or a response Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 64. Views from django.http import HttpResponse def my_view(request): return HttpResponse("Hello, world!") Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 65. Views from django.http import HttpResponse from django.template import Context, loader def my_view(request): template = loader.get_template('template.html') context = Context({ ... }) return HttpResponse(template.render(context)) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 66. Views from django.shortcuts import render def my_view(request): return render(request, 'template.html', {...}) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 67. Exercise 1 • Create a template for the homepage • Create a view that will respond with the rendered template • Connect the / URL to the view Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 68. Let’s see the code! git reset --hard ex01
- 69. Contact Form
- 70. Apps • Django believes strongly in separating chunks of a site into apps that can be reused • Ecosystem of reusable apps available • Create an app; from the src directory: $ django-admin.py startapp myapp > python Scripts/django-admin.py startapp myapp Framework Middleware • Add it to INSTALLED_APPS in settings.py URLs Views Tem- Models plates Tags & DB Filters
- 71. New App Contents src/ codesmash/ myapp/ __init__.py models.py tests.py <-- you should write them! views.py urls.py <-- you'll want to make one of these forms.py <-- one of these too Framework Middleware templates/ URLs Views Tem- Models plates Tags & DB Filters
- 72. App URLs from django.conf.urls import patterns, include, url urlpatterns = patterns('myapp.views', url(r'^$', 'my_view', name='my_form'), ... ) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 73. Connecting App URLs # Use include to connect a regex to an app's urls.py # Use namespace to keep app URL names nicely isolated urlpatterns = patterns('', (r'^myapp/', include('myapp.urls', namespace='myapp')), ... ) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 74. Form Validation • Why? • Classes for each kind of input field • Form class to gather input fields • View method uses the form class to validate inputs Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 75. A Very Simple Form from django import forms class MyForm(forms.Form): name = forms.CharField(max_length=30) email = forms.EmailField() Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 76. Using a Form in a View from myapp.forms import MyForm def my_view(request): form = MyForm(request.POST or None) if request.method == "POST" and form.is_valid(): name = form.cleaned_data['name'] email = form.cleaned_data['email'] # do something great with that data return render(request, 'myapp/myform.html', { 'form': form Framework }) Middleware URLs Views Tem- Models plates Tags & DB Filters
- 77. Django Template Language • Call a function or do logic: {% ... %} • Variable substitution: {{ bar }} • Filters: Framework {{ foo|bar }} Middleware URLs Views Tem- Models plates Tags & DB Filters
- 78. Forms in Templates <html> ... <body> <form action="{% url 'myapp:my_form' %}" method="post"> {% csrf_token %} {{ form.as_p }} <button type="submit">Go!</button> </form> Framework </body> Middleware </html> URLs Views Tem- Models plates Tags & DB Filters
- 79. Sending Mail • Add an EMAIL_BACKEND in settings.py EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend' • Import and use from django.core.mail import send_mail send_mail('subject', 'message', 'sender', ['recipient', ...]) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 80. Exercise 2 • Create a contact app • Create a contact form with subject, message, and sender’s email address • Create view to display and process the form and “send” the message • Connect the view to “/contact” URL Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 81. Let’s see the code! git reset --hard ex02
- 82. Redirecting on Success • Make the POST action redirect with a GET on successful processing • Avoid “resubmit form” issues when reloading or returning to success page (browser back button) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 83. Redirecting from django.shortcuts import redirect def my_view(request): ... return redirect('namespace:name') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 84. Exercise 3 • Make a separate contact form URL and template for displaying a success message • Update the POST handler to redirect to the success page Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 85. Let’s see the code! git reset --hard ex03
- 87. Template Inheritance • Define a base template for the site • Other templates extend the base template • Blocks allow child templates to inject content into areas of the parent template Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 88. base.html <!DOCTYPE html> <html> <head> <meta name="..." content="..."> <title>{% block title %}My Site{% endblock %}</ title> </head> <body> {% block content %} {% endblock %} </body> Framework </html> Middleware URLs Views Tem- Models plates Tags & DB Filters
- 89. helloworld.html {% extends "base.html" %} {% block title %}Hello, World{% endblock %} {% block content %} <h1>Hey! Great!</h1> <p>Sure is some lovely content right here.</p> <p>Yup.</p> {% endblock %} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 90. Exercise 4 • Refactor those templates! • Make a base.html with appropriate blocks • Make other templates extend it and fill in the blocks Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 91. Let’s see the code! git reset --hard ex04
- 93. No Need to Reinvent • Django comes with a robust user framework: django.contrib.auth • Registration • Login/Logout • Password Recovery Framework • Etc. Middleware URLs Views Tem- Models plates Tags & DB Filters
- 94. Database Settings import os PROJECT_ROOT = os.path.abspath( os.path.join(os.path.dirname(__file__), "..")) DATABASES = { 'default': { 'ENGINE': 'django.db.backends.sqlite3', 'NAME': os.path.join( PROJECT_ROOT, "database.db") Framework } Middleware } URLs Views Tem- Models plates Tags & DB Filters
- 95. Create the Database $ python manage.py syncdb Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 96. Extend the UserCreationForm from django.contrib.auth.forms import UserCreationForm class RegistrationForm(UserCreationForm): class Meta(UserCreationForm.Meta): fields = ("username", "email") Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 97. Register the User form = RegistrationForm(request.POST) if form.is_valid(): form.save() Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 98. Login Aer Registration from django.contrib.auth import authenticate, login user = authenticate( username=form.cleaned_data['username'], password=form.cleaned_data['password1']) login(request, user) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 99. The User Object • Always have one in every request • Always available to templates • Can be anonymous or populated depending on whether the user has authenticated
- 100. Exercise 5 • Start a new app called • Profile page should just “accounts” display username and email • Set up a UserCreationForm • Set up templates for the subclass in accounts.forms form and profile page in with username and email templates/accounts/ • Set up a view that displays • Wire up the URLs (be sure to the form on GET give them names) • Make the view handle POSTs • Link to registration from the Framework – check the form, register the header Middleware user, log in, and redirect to a user profile page URLs Views Tem- Models plates Tags & DB Filters
- 101. Let’s see the code! git reset --hard ex05
- 102. User Login & Logout
- 103. More Reusable Goodness • django.contrib.auth provides URLs and views for login and logout • Will want to provide our own templates Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 104. URLs urlpatterns = patterns('', ... (r'auth/', include('django.contrib.auth.urls', namespace='auth')), ... ) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 105. Templates to Override • templates/registration/login.html • templates/registration/logged_out.html Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 106. Login/Logout Links {% url 'auth:login' %} {% url 'auth:logout' %} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 107. Differentiate Logged In/Out {% if user.is_authenticated %} ... {% else %} ... {% endif %} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 108. Exercise 6 • Enable auth URLs • Show username in header when user is • Add login and logout logged in links to the site header • Link to user profile when • Show login when user is user is logged in logged out, logout when user is logged in • Customize login and logout pages Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 109. Let’s see the code! git reset --hard ex06
- 110. Django Admin
- 111. Django Admin • Free CRUD! • Navigate database data by model • Make changes • Highly customizable Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 112. Enabling the Admin App • Uncomment admin lines from INSTALLED_APPS in settings.py • Uncomment admin lines from the project’s urls.py • Mini-exercise: go do that :-) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 113. Demo Time! git reset --hard ex07
- 114. CMS Pages
- 115. django.contrib.flatpages • Store simple “flat” HTML pages in the database • Has a URL, title, and content • Useful for one-off pages with no logic that don’t deserve full apps • Add/edit content via the admin app Framework Middleware • Let’s enable it now! URLs Views Tem- Models plates Tags & DB Filters
- 116. settings.py • Add to INSTALLED_APPS: django.contrib.flatpages • Add to MIDDLEWARE_CLASSES: django.contrib.flatpages.middleware.FlatpageFallback Middleware Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 117. urls.py •Change root URL to use flatpage: url(r'^$', 'django.contrib.flatpages.views.flatpage', {'url': '/' }, name='home') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 118. Make a Flatpage Template • Put it in templates/flatpages/default.html • In the title block, add: {{ flatpage.title }} • In the content block, add: {{ flatpage.content }} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 119. Let’s see the code! git reset --hard ex08
- 120. Meanwhile, in the admin app...
- 121. Conference Talks: An App with a Custom Data Model
- 122. Models • Model classes are the nouns of the system • Used to create database tables • Integrated with the ORM to interact with the database • Need to `python manage.py syncdb` when adding a new model class Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 123. Models from django.db import models class Thingy(models.Model): name = models.CharField(max_length=255) awesome = models.BooleanField(default=True) description = models.TextField(blank=True) def __str__(self): return self.name Framework Middleware def __unicode__(self): # note: not in Python 3 return unicode(str(self)) URLs Views Tem- Models plates Tags & DB Filters
- 124. Exercise 9 • Create a “talks” app to manage talks • Create a Talk model; it should have: • title - up to 255 characters • approved - true or false, default false • recording_release - true or false, default false • abstract - text describing the talk Framework • outline - text outlining the talk Middleware URLs • notes - text about the talk that won't be public Views Tem- Models plates Tags & DB Filters
- 125. Let’s see the code! git reset --hard ex09
- 126. Wiring the Model for Admin Access • Each app manages its own admin wiring • Goes into an admin.py within the app Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 127. admin.py from django.contrib import admin from myapp.models import Thingy admin.site.register(Thingy) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 128. Exercise 10 • Create an admin.py for the talks app • Register the Talk model • Start up the admin app and verify that Talks appears Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 129. Let’s see the code! git reset --hard ex10
- 130. Pluralize All the Thingys! class Thingy(model.models): ... class Meta: verbose_name_plural = "Thingies" Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 131. Relations • Foreign key (one-to-many) • Many-to-many Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 132. Foreign Key Relations class Thingy(models.Model): ... class Gadget(models.Model): ... class Gizmo(models.Model): thingy = models.ForeignKey(Thingy) gadget = models.ForeignKey(Gadget, blank=True, null=True) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 133. Many-to-Many Relations class Thingy(models.Model): ... class Gizmo(models.Model): thingies = models.ManyToManyField(Thingy) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 134. Saving a Model Object thingy = Thingy() thingy.size = 'big' thingy.save() gadget = Gadget(thingy=thingy) gadget.save() gizmo = Gizmo(thingies=[thingy]) gizmo.save() Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 135. Exercise 11 • Create new model classes • All should have a name, up for foreign keys: to 255 characters • Category • All should have a __str__; Time Slot’s should use • Talk Type strime (see strime.net) • Audience Skill Level • Location and Time Slot should be optional • Location • Do a many-to-many on Framework django.contrib.auth.models. Middleware • Time Slot User for talk speakers URLs Views Tem- Models plates Tags & DB Filters
- 136. Let’s see the code! git reset --hard ex11
- 137. Meanwhile, in the admin app...
- 138. Changing Existing Models • Adding/removing/changing fields in a model requires a schema migration • Django doesn’t support it out of the box • Pro mode: use South Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 139. Cheesy Precompiler Way $ ./manage.py dbshell > DROP TABLE talks; $ ./manage.py syncdb Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 140. Querying the Model all_thingies = Thingy.objects.all() single_thingy = Thingy.objects.get(id=1) big_thingies = Thingy.objects.filter(size='big') ordered_thingies = Thingy.objects.all().order_by('size') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 141. Relations in Templates • When a model object retrieved from the ORM has relations, you get a relation manager and not an actual iterable collection • Need to call .all() (or get or filter) on it before you get back the related model objects Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 142. Relations in Templates {% for gizmo in gizmos %} {% for thingy in gizmo.thingies.all %} ... {% endfor %} {% endfor %} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 143. Exercise 12 • Create a view and template to display a list of all talks, ordered by title • Be sure to display all of the talk speakers Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 144. Let’s see the code! git reset --hard ex12
- 145. Optimizing Queries • What we just did will make lots of extra database queries (because of the loops) • Go read up on: • select_related: does a join in SQL • prefetch_related: queries in advance, caches results, allows “join” in Python
- 146. Model Managers • A place to encapsulate data queries • Extend to provide extra queries with developer-friendly interfaces Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 147. Model Managers class ThingyManager(models.Manager): def big_ones(self): return self.get_query_set().filter(size='big') def of_color(self, color): return self.get_query_set().filter(color=color) class Thingy(models.Model): Framework objects = ThingyManager() Middleware URLs Views Tem- Models plates Tags & DB Filters
- 148. Using a Model Manager big_thingies = Thingy.objects.big_ones() green_thingies = Thingy.objects.of_color('green') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 149. Exercise 13 • Move the queries from the previous exercise into a TalkManager • Change the queries to only get talks that have been approved Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 150. Let’s see the code! git reset --hard ex13
- 151. Generic Views • Many views fall into the same patterns • Django provides generic view classes for things like showing a list of objects, creating an object, updating an object, deleting, etc. • Subclass and set properties or override certain methods to customize Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 152. Generic List Views from django.views.generic import ListView class ThingyListView(ListView): queryset = Thingy.objects.all() Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 153. Generic List View URLs from django.conf.urls import patterns, include, url from myapp.views import ThingyListView urlpatterns = patterns('myapp.views', ... url(r'^$', ThingyListView.as_view(), name='things') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 154. Generic List View Templates • Generic List Views are automatically wired to templates • Naming convention: lowercase model name + “_list.html”, eg: templates/myapp/thingy_list.html Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 155. Exercise 14 • Replace the view that lists talks with a generic list view • Redo the URL mapping to use your new generic list view subclass Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 156. Let’s see the code! git reset --hard ex14
- 157. Can You Guess What’s Next? • Need to create new talks • We could do it the hard way... • Make a Form • Make a View • Read validated data, put it into a model object Framework • Save the model, redirect... Middleware URLs Views Tem- Models plates Tags & DB Filters
- 158. Model Forms from django import forms from myapp.models import Thingy class ThingyForm(forms.ModelForm): class Meta: model = Thingy exclude = ('flavor', 'user') Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 159. Generic Create Views from django.views.generic.edit import CreateView from myapp.forms import ThingyForm class ThingyCreationView(CreateView): model = Thingy form_class = ThingyForm success_url = "/accounts/profile" Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 160. Generic Create View Templates • Generic Create Views are automatically wired to templates • Naming convention: lowercase model name + “_form.html”; eg: templates/myapp/thingy_form.html Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 161. Exercise 15 • Make a Generic Create • Be sure to connect a View and Model Form to “create” URL to the new submit new talk Generic Create View proposals • Don’t forget a template! • Exclude approval status, location, and time slot • Link to the create form (since the speaker from user profile doesn’t control them) • List user’s submitted Framework talks on user profile Middleware URLs Views Tem- Models plates Tags & DB Filters
- 162. Let’s see the code! git reset --hard ex15
- 163. Generic Edit Views from django.shortcuts import resolve_url from django.view.generic.edit import UpdateView from myapp.forms import ThingyForm class ThingyUpdateView(UpdateView): form_class = ThingyForm queryset = Thingy.objects.all() def get_success_url(self): return resolve_url('myapp:thingy') def get_context_data(self, **kwargs): Framework context = super(ThingyUpdateView, self).get_context_data(**kwargs) context['editing'] = True Middleware return context URLs Views Tem- Models plates Tags & DB Filters
- 164. Generic Edit View URLs from django.conf.urls import patterns, include, url from myapp.views import ThingyUpdateView urlpatterns = patterns('myapp.views', ... url(r'(?P<pk>[0-9]+)$', ThingyUpdateView.as_view(), name='update'), ) Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 165. Exercise 16 • Create a Generic Edit View for talks • Use the Model Form from the previous exercise • Be sure to wire it to a URL for editing • Change the existing template to indicate whether we’re editing or creating Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 166. Let’s see the code! git reset --hard ex16
- 167. Security in Views • Can you spot a security problem in the previous exercise? • Anyone can edit any talk! • Generic views can restrict access by limiting the queryset available in the view Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 168. Restricting Object Access # In models.py... class ThingyManager(models.Manager): def for_user(self, user): return self.get_query_set().filter(user=user) # In views.py... class ThingyUpdateView(UpdateView): def get_queryset(self): Framework return Thingy.objects.for_user( Middleware self.request.user) URLs Views Tem- Models plates Tags & DB Filters
- 169. Exercise 17 • Lock down the update view from the previous exercise so that a talk may only be edited by its speakers Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 170. Let’s see the code! git reset --hard ex17
- 171. Read-Only Data in Generic Edit Views • Model Form automatically builds form elements for everything in the model • Model Form excludes anything that it was told to exclude • Excluded fields are still available as attributes of a variable called “object” (the Framework object being displayed/edited) Middleware URLs Views Tem- Models plates Tags & DB Filters
- 172. Read-Only Data in Generic Edit Views <form ...> {% csrf_token %} {{ form.as_p }} <p><input type="text" id="flavor" value="{{ object.flavor }}" disabled ></p> <input type="submit" value="Save Changes"> </form> Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 173. Exercise 18 • Change the talk form from the previous exercises • Show time slot, location, and approval status without allowing them to be modified Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 174. Let’s see the code! git reset --hard ex18
- 175. Requiring Login from django.contrib.auth.decorators import login_required @login_required def my_login_only_view(request): return render(request, "myapp/my_view.html") Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 176. Exercise 19 • Require login on the user profile page Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 177. Let’s see the code! git reset --hard ex19
- 178. Custom Template Filters • Django comes with many filters • You can add your own • Function that accepts a value and returns a string Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 179. Defining a Custom Filter # In myapp/templatetags/myfilters.py... from django import template from django.utils.html import format_html register = template.Library() @register.filter def my_filter(value): ... Framework return format_html("...") Middleware URLs Views Tem- Models plates Tags & DB Filters
- 180. Using a Custom Filter {% load myfilters %} {% block content %} <p>{{ foo|my_filter }}</p> <p>{{ bar }}</p> {% endblock %} Framework Middleware URLs Views Tem- Models plates Tags & DB Filters
- 181. Exercise 20 • Create a custom filter function “boolean_icon” that will show one image if a value is True and another if it’s False • Use the boolean_icon in the user’s profile to indicate whether a talk has been approved • Use static icons from the admin site: Framework from django.contrib.admin.templatetags.admin_static import static Middleware icon_url = static('admin/img/icon-{0}.gif'.format( URLs {True: 'yes', False: 'no', None: 'unknown'}[value]) Views Tem- Models plates Tags & DB Filters
- 182. Let’s see the code! git reset --hard ex20
- 183. Bonus Exercises • Show talks by time slot and/or location • Blog; include RSS feed • Sponsorship; include sponsor image upload and display • Enhance user profiles; include image upload, default to Gravatar Framework Middleware • Room swap/ticket swap URLs Views Tem- Models plates Tags & DB Filters
- 184. A Little Bit About Deployment
- 185. Django
- 186. Varnish Nginx Static Files Gunicorn Django Django Django
- 187. Where to Deploy • Gondor.io • Heroku • Webfaction • Google App Engine (if that’s what you’re into) • Your favorite VPS (Rackspace, AWS, etc.)
- 188. Questions?
- 189. Links • http://python.org • https://djangoproject.com • https://github.com/finiteloopsoware/ django-precompiler
- 190. Credits • Image from Django Unchained by Sony Pictures http://www.nydailynews.com/entertainment/tv-movies/django-star-foxx-life- built-race-article-1.1220275 • Image of Django Reinhardt by ~Raimondsy http://raimondsy.deviantart.com/art/Django-Reinhardt-314914547 • Other images from ClipArt Etc. http://etc.usf.edu/clipart/
- 191. Contact Information Mike Crute David Stanek Finite Loop Soware American Greetings http://mike.crute.org http://traceback.org @mcrute @dstanek Mike Pirnat American Greetings http://mike.pirnat.com @mpirnat
- 192. Thanks for coming & happy hacking!