Django tips & tricks

Django: Tips & Tricks

by Renyi Khor

renyi.ace@gmail.com@renyikhor

https://github.com/renyi/django-tips-and-tricks

Wednesday, June 19, 13

Disclaimer

• I’m not a super pro pythonista, but I’m a very lazy one.

Disclaimer

• Speed - means programmer’s programming speed, unless specified otherwise.

Disclaimer

• I like to do things as short and as easy as possible.

Disclaimer

• I like to do things as short and as easy as possible.

• DRYKISS = Don’t repeat yourself + Keep it super simple

ACE EdVenture PixelHead of R&D and Lead Developer

SchoolHubSchool Management System

What we use python for ?SchoolHub is built on top of Django Web Framework

ACE EdVenture StudioHead of R&D

ChemQuest: Petticles in PerilChemistry based RPG game.

What we use python for ?Most of the web components are built with

Django Web Framework(Web login, Game Achievements, etc.)

#1: Boilerplate Everything (that you can)

settings.py

• use lists[] instead of tuples() in default_settings.py

• Use list methods - add(), remove(), +=

• Default naming convention to project name

• use project as default “theme” app for project

1 # default_settings.py 2 3 DEBUG = False 4 TEMPLATE_DEBUG = False 5 USE_SOUTH = True 6 ADMINS = [('Devtune Admin', 'admin@devtune.biz')] 7 MANAGERS = ADMINS 8 USE_I18N = True 9 USE_L10N = True 10 LANGUAGE_CODE = "en-gb" 11 USE_TZ = True 12 TIME_ZONE = 'Asia/Kuala_Lumpur' 13 INTERNAL_IPS = ["127.0.0.1"] 14 SESSION_ENGINE = 'django.contrib.sessions.backends.cached_db' 15 SESSION_EXPIRE_AT_BROWSER_CLOSE = True 16 SITE_ID = 1 17 STATIC_URL = '/static/' 18 MEDIA_URL = '/media' 19 INSTALLED_APPS = [ 20 "django.contrib.admin", 21 "django.contrib.auth", 22 "django.contrib.contenttypes", 23 "django.contrib.sessions", 24 "django.contrib.sites", 25 "django.contrib.sitemaps", 26 "django.contrib.staticfiles", 27 "compressor", 28 ]

1 # settings.py 2 3 from .default_settings import * 4 5 # Inserts default theme app 6 INSTALLED_APPS.insert(1, "my_project.themes.default") 7 8 # Removes CSRF checking 9 if "django.middleware.csrf.CsrfViewMiddleware" in MIDDLEWARE_CLASSES: 10 MIDDLEWARE_CLASSES.remove("django.middleware.csrf.CsrfViewMiddleware") 11 12 # LOCAL SETTINGS # 13 try: 14 from local_settings import * 15 except ImportError: 16 pass 17 18 # DYNAMIC SETTINGS # 19 try: 20 from mezzanine.utils.conf import set_dynamic_settings 21 except ImportError: 22 pass 23 else: 24 set_dynamic_settings(globals())

1 # settings.py 2 3 import os 4 PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__)) 5 PROJECT_DIRNAME = PROJECT_ROOT.split(os.sep)[-1] 6 7 # User project directory name as default "theme" app 8 INSTALLED_APPS.insert(1, "%s" % PROJECT_DIRNAME) 9 10 ROOT_URLCONF = '%s.urls' % PROJECT_DIRNAME 11 CACHE_MIDDLEWARE_KEY_PREFIX = '%s' % PROJECT_DIRNAME 12 CACHE_MIDDLEWARE_ALIAS = '%s' % PROJECT_DIRNAME 13 CSRF_COOKIE_NAME = '%s_csrftoken' % PROJECT_DIRNAME 14 LANGUAGE_COOKIE_NAME = '%s_language' % PROJECT_DIRNAME 15 SESSION_COOKIE_NAME = '%s_session' % PROJECT_DIRNAME 16 STATIC_ROOT = '/static/%s/' % PROJECT_DIRNAME 17 MEDIA_ROOT = '/media/%s/' % PROJECT_DIRNAME 18 WSGI_APPLICATION = '%s.wsgi.application' % PROJECT_DIRNAME 19 20 # Celery 21 BROKER_VHOST = PROJECT_DIRNAME 22 BROKER_URL = '%s%s' % (BROKER_URL, BROKER_VHOST) 23 24 DATABASES = { 25 "default": { 26 "ENGINE": "django.db.backends.postgresql_psycopg2", 27 "NAME": "%s" % PROJECT_DIRNAME, 28 "HOST": "127.0.0.1", 29 } 30 } 31 32 CACHES = { 33 'default': { 34 'BACKEND': 'django.core.cache.backends.memcached.PyLibMCCache', 35 'LOCATION': ['127.0.0.1:11211'], 36 'KEY_PREFIX': '%s' % PROJECT_DIRNAME, 37 } 38 }

1 # local_settings.py 2 # (developer's version) 3 4 DEBUG = True 5 TEMPLATE_DEBUG = DEBUG 6 COMPRESS_ENABLED = False 7 8 DATABASES = { 9 "default": { 10 "ENGINE": "django.db.backends.sqlite3", 11 "NAME": "dev.db", 12 } 13 } 14 15 CACHES = { 16 'default': { 17 'BACKEND': 'django.core.cache.backends.dummy.DummyCache', 18 } 19 } 20 21 22 CELERY_CACHE_BACKEND = "dummy" 23 EMAIL_BACKEND = 'kopio.core.mailer.backend.DbBackend' 24 MAILER_EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend' 25 SESSION_ENGINE = "django.contrib.sessions.backends.signed_cookies"

urls.py

• boilerplate default urls (index.html, etc.)

• load urls according to settings.INSTALLED_APPS

1 # urls.py 2 3 from django.conf.urls import patterns, include, url 4 5 6 urlpatterns = patterns('', 7 ('', include("default_app.urls")), 8 ('', include("mezzanine.urls")), 9 )

1 # default_urls.py 2 3 urlpatterns = patterns('', 4 # Default index.html 5 url(r'^$', TemplateView.as_view(template_name='index.html'), name="home"), 6 7 # Default favicon 8 url(r'^favicon\.ico/$', RedirectView.as_view(url='/static/img/favicon. 9 ico'), name="favicon"), 10 ) 11 12 # Default robots.txt 13 urlpatterns += patterns('', 14 url(r'^robots\.txt/$', TemplateView.as_view(template_name='robots.txt')), 15 ) 16 17 # Admin urls 18 if "django.contrib.admin" in settings.INSTALLED_APPS: 19 from django.contrib import admin 20 admin.autodiscover() 21 22 urlpatterns += patterns("", 23 (r"âdmin/", include(admin.site.urls)), 24 ) 25 26 # Other apps 27 if "userena" in settings.INSTALLED_APPS: 28 urlpatterns += patterns("", 29 (r'ûsers/', include('userena.urls')), 30 ) 31 32 if "selectable" in settings.INSTALLED_APPS: 33 urlpatterns += patterns("", 34 url(r"^selectable/", include("selectable.urls")), 35 ) 36 37 if "actstream" in settings.INSTALLED_APPS: 38 urlpatterns += patterns("", 39 ('âctivity/', include('actstream.urls')), 40 )

1 # urls.py 2 3 # Media and Static files for development 4 if settings.DEBUG: 5 # Static files 6 from django.contrib.staticfiles.urls import staticfiles_urlpatterns 7 urlpatterns += staticfiles_urlpatterns() 8 9 # Media files 10 from django.conf.urls.static import static 11 urlpatterns += static(settings.MEDIA_URL, document_root=settings. 12 MEDIA_ROOT)

#2: ‘Dynamic’ App Loading

• Automatically load all apps in a directory.

• Useful for plugins*

• For more complex usage, .autodiscover() might be a better choice

1 # installed_plugins_list.py 2 3 def installed_plugins_list(plugin_path=None): 4 """Function to get a list of plugins from plugin_path 5 """ 6 import os 7 8 path = os.path.dirname(__file__) 9 path = os.path.join(path, plugin_path) 10 11 installed_plugins = [] 12 for module in os.listdir(path): 13 if os.path.isdir(path + '/' + module) == True: 14 installed_plugins.append(module) 15 return installed_plugins

1 ########################## 2 # LABS SETTINGS # 3 ########################## 4 # Developer's playground # 5 # Play at ur own risk # 6 ########################## 7 8 if LABS_ENABLED and not "sis.labs" in INSTALLED_APPS: 9 from .installed_plugins_list import installed_plugins_list 10 11 TEMPLATE_CONTEXT_PROCESSORS += [ 12 "sis.context_processors.sis_labs" 13 ] 14 15 # Loads all modules from sis.plugins 16 for plugin in installed_plugins_list('plugins'): 17 INSTALLED_APPS.insert(0, "sis.plugins.%s" % plugin) 18 19 # Loads all modules from sis.labs.ui 20 for plugin in installed_plugins_list('labs/ui'): 21 INSTALLED_APPS.insert(0, "sis.labs.ui.%s" % plugin) 22 23 # Loads all modules from sis.labs.apps 24 INSTALLED_APPS.append('sis.labs') 25 for plugin in installed_plugins_list('labs/app'): 26 INSTALLED_APPS.append(0, "sis.labs.app.%s" % plugin)

#3: Django Themes

• Themes are just Django apps.

• Actually, themes are Django app with static files and templates.

• Themes can be overridden, just like how we override templates.

• For more information, https://github.com/renyi/mezzanine-themes

Typical theme structuremy_awesome_theme/

- static/- img/

- js/ - scripts.js

- css/ - local.css

- templates/- base.html- index.html

- includes/main.html

Where to put the themes ?

1. Use main app as theme# directory structuremy_project/my_app/templatesmy_project/my_app/static

# in settings.pyINSTALLED_APPS.insert(1, "my_app")

2. Have a dedicated theme directory

# directory structuremy_project/my_app/themes/default/templatesmy_project/my_app/themes/default/static

# in settings.pyINSTALLED_APPS.insert(1, "my_app.themes.default")

#4: Django plugins with {% overextends %}

• {% overextends %} is written by @stephen_mcd for Mezzanine CMS.

• Also available as pluggable app. https://github.com/stephenmcd/django-overextends

• Allows circular template inheritance. (base.html can “extend” base.html)

• This allows for simple way of managing plugable apps (javascripts libraries, etc.) or let’s call it “plugins”.

1  2 {% extends "base.html" %} 3 4 5 {% block header %} 6 <h1>Hello Title</h1> 7 {% endblock %} 8 9 10 {% block main %} 11 <p>Hello Body</p> 12 {% endblock %}

1  2 <!DOCTYPE html> 3 <head> 4 <meta charset="utf-8"> 5 {% block base_styles %}{% endblock %} 6 </head> 7 <body> 8 <header id="header"> 9 {% block header %}{% endblock %} 10 </header> 11 12 <div role="main" id="main"> 13 {% block main %}{% endblock %} 14 </div> 15 16 <footer id="footer"> 17 {% block footer %}{% endblock %} 18 </footer> 19 20 {% block js_libs %}{% endblock %} 21 </body> 22 </html>

1  2 {% overextends "base.html" %} 3 4 5 {% block js_libs %} 6 {{ block.super }} 7 <script src="//code.jquery.com/jquery-1.8.3.min.js"></script> 8 {% endblock %}

1  2 {% overextends "base.html" %} 3 4 5 {% block base_styles %} 6 {{ block.super }} 7 <link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3. 8 1/css/bootstrap-combined.min.css" rel="stylesheet"> 9 {% endblock %} 10 11 12 {% block js_libs %} 13 {{ block.super }} 14 <script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3. 15 1/js/bootstrap.min.js"></script> 16 {% endblock %}

1  2 <!DOCTYPE html> 3 <head> 4 <meta charset="utf-8"> 5 6  7 <link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3. 8 1/css/bootstrap-combined.min.css" rel="stylesheet"> 9  10 </head> 11 <body> 12 <header id="header"> 13  14 <h1>Hello Title</h1> 15  16 </header> 17 18 <div role="main" id="main"> 19  20 <p>Hello Body</p> 21  22 </div> 23 24 <footer id="footer"> 25  26  27 </footer> 28 29  30 <script src="//code.jquery.com/jquery-1.8.3.min.js"></script> 31 <script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3. 32 1/js/bootstrap.min.js"></script> 33  34 </body> 35 </html>

1 INSTALLED_APPS = [ 2 "my_app.themes.default", 3 "my_app.plugins.jquery", 4 "my_app.plugins.bootstrap", 5 ... 6 ]

Inheritance priority

#5: Class based views

models.py

1 # models.py 2 3 from django.db import models 4 5 6 class School(models.Model): 7 title = models.CharField(_("Title"), max_length=500) 8 slug = models.CharField(_("URL"), max_length=2000) 9 10 def __unicode__(self): 11 return self.title 12 13 def save(self, *args, **kwargs): 14 """ 15 Create a unique slug by appending an index. 16 """ 17 pass 18 19 def get_slug(self): 20 """ 21 Allows subclasses to implement their own slug creation logic. 22 """ 23 return slugify(self.title)

36 class Slugged(models.Model): 37 title = models.CharField(_("Title"), max_length=500) 38 slug = models.CharField(_("URL"), max_length=2000) 39 40 class Meta: 41 abstract = True 42 43 def __unicode__(self): 44 return self.title 45 46 def save(self, *args, **kwargs): 47 """ 48 Create a unique slug by appending an index. 49 """ 50 pass 51 52 def get_slug(self): 53 """ 54 Allows subclasses to implement their own slug creation logic. 55 """ 56 return slugify(self.title)

1 # models.py 2 3 from django.db import models 4 from .base import Slugged 5 6 7 class School(Slugged): 8 pass

1 # models.py 2 3 from django.db import models 4 from .base import Slugged 5 6 class School(Slugged): 7 8 @models.permalink 9 def get_absolute_url(self): 10 return ('school_details', None, {'slug': self.slug})

1 class CrudUrl(models.Model): 2 class Meta: 3 abstract = True 4 5 def __init__(self, *args, **kwargs): 6 self._objname = self._meta.object_name.lower() 7 super(CrudUrl, self).__init__(*args, **kwargs) 8 9 @models.permalink 10 def get_absolute_url(self): 11 return ('%s_details' % self._objname, None, {'slug': self.slug}) 12 13 @models.permalink 14 def get_list_url(self): 15 return ('%s_list' % self._objname, None, {}) 16 17 @models.permalink 18 def get_create_url(self): 19 return ('%s_create' % self._objname, None, {}) 20 21 @models.permalink 22 def get_update_url(self): 23 return ('%s_update' % self._objname, None, {'slug': self.slug}) 24 25 @models.permalink 26 def get_delete_url(self): 27 return ('%s_delete' % self._objname, None, {'slug': self.slug}) 28

1 # models.py 2 3 from django.db import models 4 from .base import Slugged, CrudUrl 5 6 class School(Slugged, CrudUrl): 7 pass

urls.py

1 # urls.py 2 3 from django.conf.urls import patterns, include, url 4 from django.views.generic import (ListView, DetailView, 5 CreateView, UpdateView, DeleteView) 6 from .models import School 7 8 9 urlpatterns = patterns('', 10 url(r'^school/$', 11 ListView.as_view(), 12 name="school_list"), 13 14 url(r'^school/add/$', 15 CreateView.as_view(), 16 name="school_create"), 17 18 url(r'^school/update/(?P<slug>.*)/$', 19 UpdateView.as_view(), 20 name="school_update"), 21 22 url(r'^school/delete/(?P<slug>.*)/$', 23 DeleteView.as_view(), 24 name="school_delete"), 25 26 url(r'^school/(?P<slug>.*)/$', 27 DetailView.as_view(), 28 name="school_details"), 29 )

views.py

1 # views.py 2 3 from django.views.generic import (ListView, DetailView, 4 CreateView, UpdateView, DeleteView) 5 from .models import School 6 7 8 class SchoolListView(ListView): 9 ''' 10 Template: school/school_list.html 11 ''' 12 model = School 13 14 class SchoolDetailView(DetailView): 15 ''' 16 Template: school/school_detail.html 17 ''' 18 model = School 19 20 class SchoolCreateView(CreateView): 21 ''' 22 Template: school/school_form.html 23 ''' 24 model = School 25 26 class SchoolUpdateView(UpdateView): 27 ''' 28 Template: school/school_form.html 29 ''' 30 model = School 31 32 class SchoolDeleteView(DeleteView): 33 ''' 34 Template: school/school_confirm_delete.html 35 ''' 36 model = School

1 from django.views.generic.base import TemplateResponseMixin 2 3 class AjaxTemplateResponseMixin(TemplateResponseMixin): 4 def get_template_names(self): 5 """ 6 Return a list of template names to be used for the request. 7 """ 8 try: 9 names = super(AjaxTemplateResponseMixin, self).get_template_names() 10 except ImproperlyConfigured: 11 names = [] 12 13 try: 14 opts = self.form_class._meta.model._meta 15 except: 16 try: 17 opts = self.object_list.model._meta 18 except: 19 try: 20 opts = self.object._meta 21 except: 22 opts = None 23 24 # Generates template name based on object name 24 if opts: 25 opts_list = (opts.app_label, opts.object_name.lower(), self. 26 template_name_suffix) 27 28 if self.request.is_ajax(): 29 name = "%s/includes/%s%s.html" % opts_list 30 31 else: 32 name = "%s/%s%s.html" % opts_list 33 34 names.append(name) 35 36 return names

1 # views.py 2 3 from django.views.generic import (ListView, DetailView, 4 CreateView, UpdateView, DeleteView) 5 from .models import School 6 from .mixin import AjaxTemplateResponseMixin 7 8 9 class SchoolListView(ListView, AjaxTemplateResponseMixin): 10 ''' 11 Template: school/school_list.html 12 AJAX Template: school/includes/school_list.html 13 ''' 14 model = School 15 16 class SchoolDetailView(DetailView, AjaxTemplateResponseMixin): 17 ''' 18 Template: school/school_detail.html 19 AJAX Template: school/includes/school_detail.html 20 ''' 21 model = School 22 23 class SchoolCreateView(CreateView, AjaxTemplateResponseMixin): 24 ''' 25 Template: school/school_form.html 26 AJAX Template: school/includes/school_form.html 27 ''' 28 model = School 29 30 class SchoolUpdateView(UpdateView, AjaxTemplateResponseMixin): 31 ''' 32 Template: school/school_form.html 33 AJAX Template: school/includes/school_form.html 34 ''' 35 model = School 36

8 class FilterMixin(object): 9 allowed_filters = {} 10 11 def get_queryset_filters(self): 12 filters = {} 13 14 for item in self.request.GET: 15 allowed = self.allowed_filters.get(item) 16 if allowed: 17 keyname = "%s" % allowed 18 filter_values = self.request.GET.getlist(item) 19 filters[keyname] = filter_values 20 return filters 21 22 def get_queryset(self): 23 qs = super(FilterMixin, self).get_queryset() 24 return qs.filter(**self.get_queryset_filters())

1 # views.py 2 3 from django.views.generic import (ListView, DetailView, 4 CreateView, UpdateView, DeleteView) 5 from .models import School 6 from .mixin import AjaxTemplateResponseMixin, FilterMixin 7 8 9 class SchoolListView(ListView, FilterMixin, AjaxTemplateResponseMixin): 10 ''' 11 Template: school/school_list.html 12 AJAX Template: school/includes/school_list.html 13 ''' 14 model = School 15 allowed_filters = { 16 'title': 'title__icontains', 17 'slug': 'slug__icontains', 18 } 19

urls.py

1 # urls.py 2 3 from django.conf.urls import patterns, include, url 4 from .views import (SchoolListView, SchoolDetailView, 5 SchoolCreateView, SchoolUpdateView, 6 SchoolDeleteView) 7 from .models import School 8 9 10 urlpatterns = patterns('', 11 url(r'^school/$', 12 SchoolListView.as_view(), 13 name="school_list"), 14 15 url(r'^school/add/$', 16 SchoolCreateView.as_view(), 17 name="school_create"), 18 19 url(r'^school/update/(?P<slug>.*)/$', 20 SchoolUpdateView.as_view(), 21 name="school_update"), 22 23 url(r'^school/delete/(?P<slug>.*)/$', 24 SchoolDeleteView.as_view(), 25 name="school_delete"), 26 27 url(r'^school/(?P<slug>.*)/$', 28 SchoolDetailView.as_view(), 29 name="school_details"), 30 )

F.A.Q.

1. Row based permission ?

Django Guardian(https://github.com/lukaszb/django-guardian)

2. Custom User Model ?

Pros - You don’t need a user profile model- Faster, as you don’t have to refer to profiles as foreign keys.- More flexibility

Cons- might break contrib.admin- might break old apps- might break stuffs tied to user (like permission) if custom model is not implemented correctly.

Conclusion- Yes, if you’re just extending the user model. If you inherit from AbstractUser, you should be fine.- No, if you want to override existing fields or functions. Unless you know what you’re doing, you might end up breaking compatibility with other apps.

Implementation- Add to settings.py, AUTH_USER_MODEL = 'myuser.MyModel'.

Thank You !by Renyi Khor

renyi.ace@gmail.com@renyikhor

https://github.com/renyi/django-tips-and-tricks

Django tips & tricks

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