A collection of Django utilities, built by FatBox
Project description
This is a collection of general utilities for Django projects built by FatBox.
Installation
Install using pip:
pip install fatbox-django-utils
If you’re going to use the Template Tags then you also need to add fatbox_utils to your INSTALLED_APPS setting.
These utilities require Django 1.3+. They may work with earlier versions but haven’t been tested.
Rendering templates
render_to decorator
The render_to decorator allows you to very easily render templates from your view functions. Simply decorate your view function and specify the name of the template to render to, then return a dict from your view function that contains variables that will be in the context when rendering the template.
from fatbox_utils.decorators import render_to
@render_to('myapp/template.html')
def myview(request):
return {
'var1': var1,
'var2': var2
}You can change the template on the fly by returning a list or tuple where the first element is the name of the template and the second element is the dict to use for the context.
@render_to('myapp/template.html')
def myview(request):
context = {
'var1': var1,
'var2': var2
}
# if something is true then use our other template
if something_is_true:
return ('other_template.html', context)
# otherwise use the default template
return contextLastly if you don’t return a dict or a list/tuple then render_to will just return what you give it. This ensures that if you return things like HttpResponseRedirect objects they will work as expected, but also means that you are free to craft your own response should it be required. Anything that’s valid to return from a standard Django view will work.
Humanize
humanize_time function
The humanize_time function summarizes time based on the units you provide to it. For example here is what is run in the doc tests:
>>> from fatbox_utils.humanize import humanize_time
>>> humanize_time(173, "hours")
u'1 week, 5 hours'
>>> humanize_time(17313, "seconds")
u'4 hours, 48 minutes, 33 seconds'
>>> humanize_time(5400, "seconds")
u'1 hour, 30 minutes'
>>> humanize_time(90, "weeks")
u'1 year, 10 months, 2 weeks'
>>> humanize_time(42, "months")
u'3 years, 6 months'
>>> humanize_time(500, "days")
u'1 year, 5 months, 3 weeks, 3 days'Cache
delete_template_fragment_cache function
This is a function that deletes a named template fragment cache.
See: http://djangosnippets.org/snippets/2723/
In your template:
{% load cache %}
{% cache 3600 my_cache_block request.user.username %}
...
{% endcache %}And in your view:
from fatbox_utils.cache import delete_template_fragment_cache
def my_view(request):
...
delete_template_fragment_cache("my_cache_block", request.user.username)
...i18n / Translation
This package includes a number of different utilities for managing and working with i18n / translation in your project.
current_lang context processor
This is a context processor that adds current_lang to your template context as a 2 letter language code (ie. en, fr, pt, etc).
Just add fatbox_utils.context_processors.current_lang to the TEMPLATE_CONTEXT_PROCESSORS setting.
ManualLanguageMiddleware
This is a middleware class that allows you to force the language used by the Django translation layer based on a querystring parameter.
To use it simply add fatbox_utils.middleware.ManualLanguageMiddleware to the MIDDLEWARE_CLASSES setting. Then you can pass a two character language code to a get parameter named lang to activate a specific language.
translatable_property for Models
Often times when working on a project that deals with multiple languages you want to have certain properties of a model translatable. The translatable_property class provides a convenient interface to define your properties that should be available in multiple languages.
Consider the following example models.py file:
from django.db import models
from fatbox_utils.i18n import translatable_property, TranslatableModel
class Event(models.Model):
start = models.DateTimeField()
end = models.DateTimeField()
title = translatable_property('title', 'translations')
details = translatable_property('details', 'translations')
class EventTranslation(TranslatableModel):
event = models.ForeignKey(
Event,
related_name='translations'
)
title = models.CharField(
max_length=32
)
details = models.TextField()What this does is add two models Event and EventTranslation where the EventTranslation model has a foreign key to Event and sets up a related manager named translations.
The EventTranslation model extends from TranslatableModel so that it will have the required language field setup. The language field is a CharField with max_length=2, choices=settings.LANGUAGES set for options. If you require different handling for your language selection you can simply extend from Django’s base models.Model and define your own language field.
On the Event model we define two properties using the translatable_property class. When defining these properties the first argument is the field on the related model and the second argument is the name of the manager that we can use to lookup the related model that corresponds to the current language.
When you access one of the translatable_property properties on your model it will try to fetch the related object from the translations manager where the related object has a field named language that matches the current language, as defined by the get_language function from the django.utils.translation package. If it can’t find a related object with a matching language field it will then try to get one with the default language, as defined by settings.DEFAULT_LANGUAGE.
Performance Optimization
If you don’t do any optimization of your querysets once you reach even a modest number of Event objects iterating over their querysets can become a HUGE burden on your database due to the number of SELECT lookups it needs to do when fetching all of the related EventDescription objects.
To combat this you can use Django’s prefetch_related queryset function to fetch all of the related translations in one fell swoop, reducing the number of queries to 2.
Event.objects.filter(...).prefetch_related('translations')Admin Integration
Once you have your models setup with translatable_property then you can simply use normal Django Inlines without having to worry about complex admin site configuration.
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