This tutorial begins where Tutorial 1 left off. We’re continuing the Web-poll application and will focus on Django’s automatically-generated admin site.
Philosophy
Generating admin sites for your staff or clients to add, change and delete content is tedious work that doesn’t require much creativity. For that reason, Django entirely automates creation of admin interfaces for models.
Django was written in a newsroom environment, with a very clear separation between “content publishers” and the “public” site. Site managers use the system to add news stories, events, sports scores, etc., and that content is displayed on the public site. Django solves the problem of creating a unified interface for site administrators to edit content.
The admin isn’t intended to be used by site visitors. It’s for site managers.
The Django admin site is not activated by default – it’s an opt-in thing. To activate the admin site for your installation, do these three things:
Uncomment "django.contrib.admin"
in the INSTALLED_APPS
setting.
Run python manage.py syncdb
. Since you have added a new application
to INSTALLED_APPS
, the database tables need to be updated.
Edit your mysite/urls.py
file and uncomment the lines that reference
the admin – there are three lines in total to uncomment. This file is a
URLconf; we’ll dig into URLconfs in the next tutorial. For now, all you
need to know is that it maps URL roots to applications. In the end, you
should have a urls.py
file that looks like this:
from django.conf.urls import patterns, include, url # Uncomment the next two lines to enable the admin: from django.contrib import admin admin.autodiscover() urlpatterns = patterns('', # Examples: # url(r'^$', '{{ project_name }}.views.home', name='home'), # url(r'^{{ project_name }}/', include('{{ project_name }}.foo.urls')), # Uncomment the admin/doc line below to enable admin documentation: # url(r'^admin/doc/', include('django.contrib.admindocs.urls')), # Uncomment the next line to enable the admin: url(r'^admin/', include(admin.site.urls)), )
(The bold lines are the ones that needed to be uncommented.)
Let’s start the development server and explore the admin site.
Recall from Tutorial 1 that you start the development server like so:
python manage.py runserver
Now, open a Web browser and go to “/admin/” on your local domain – e.g., http://127.0.0.1:8000/admin/. You should see the admin’s login screen:
Doesn’t match what you see?
If at this point, instead of the above login page, you get an error page reporting something like:
ImportError at /admin/
cannot import name patterns
...
then you’re probably using a version of Django that doesn’t match this tutorial version. You’ll want to either switch to the older tutorial or the newer Django version.
Now, try logging in. (You created a superuser account in the first part of this tutorial, remember? If you didn’t create one or forgot the password you can create another one.) You should see the Django admin index page:
You should see a few types of editable content, including groups, users and sites. These are core features Django ships with by default.
But where’s our poll app? It’s not displayed on the admin index page.
Just one thing to do: We need to tell the admin that Poll
objects have an admin interface. To do this, create a file called
admin.py
in your polls
directory, and edit it to look like this:
from polls.models import Poll
from django.contrib import admin
admin.site.register(Poll)
You’ll need to restart the development server to see your changes. Normally, the server auto-reloads code every time you modify a file, but the action of creating a new file doesn’t trigger the auto-reloading logic.
Now that we’ve registered Poll
, Django knows that it should be displayed on
the admin index page:
Click “Polls.” Now you’re at the “change list” page for polls. This page displays all the polls in the database and lets you choose one to change it. There’s the “What’s up?” poll we created in the first tutorial:
Click the “What’s up?” poll to edit it:
Things to note here:
DateTimeField
,
CharField
) correspond to the appropriate HTML
input widget. Each type of field knows how to display itself in the Django
admin.DateTimeField
gets free JavaScript
shortcuts. Dates get a “Today” shortcut and calendar popup, and times get
a “Now” shortcut and a convenient popup that lists commonly entered times.The bottom part of the page gives you a couple of options:
If the value of “Date published” doesn’t match the time when you created the
poll in Tutorial 1, it probably means you forgot to set the correct value for
the TIME_ZONE
setting. Change it, reload the page and check that
the correct value appears.
Change the “Date published” by clicking the “Today” and “Now” shortcuts. Then click “Save and continue editing.” Then click “History” in the upper right. You’ll see a page listing all changes made to this object via the Django admin, with the timestamp and username of the person who made the change:
Take a few minutes to marvel at all the code you didn’t have to write. By
registering the Poll model with admin.site.register(Poll)
, Django was able
to construct a default form representation. Often, you’ll want to customize how
the admin form looks and works. You’ll do this by telling Django the options
you want when you register the object.
Let’s see how this works by re-ordering the fields on the edit form. Replace
the admin.site.register(Poll)
line with:
class PollAdmin(admin.ModelAdmin):
fields = ['pub_date', 'question']
admin.site.register(Poll, PollAdmin)
You’ll follow this pattern – create a model admin object, then pass it as the
second argument to admin.site.register()
– any time you need to change the
admin options for an object.
This particular change above makes the “Publication date” come before the “Question” field:
This isn’t impressive with only two fields, but for admin forms with dozens of fields, choosing an intuitive order is an important usability detail.
And speaking of forms with dozens of fields, you might want to split the form up into fieldsets:
class PollAdmin(admin.ModelAdmin):
fieldsets = [
(None, {'fields': ['question']}),
('Date information', {'fields': ['pub_date']}),
]
admin.site.register(Poll, PollAdmin)
The first element of each tuple in fieldsets
is the title of the fieldset.
Here’s what our form looks like now:
You can assign arbitrary HTML classes to each fieldset. Django provides a
"collapse"
class that displays a particular fieldset initially collapsed.
This is useful when you have a long form that contains a number of fields that
aren’t commonly used:
class PollAdmin(admin.ModelAdmin):
fieldsets = [
(None, {'fields': ['question']}),
('Date information', {'fields': ['pub_date'], 'classes': ['collapse']}),
]
Now that the Poll admin page is looking good, let’s make some tweaks to the “change list” page – the one that displays all the polls in the system.
Here’s what it looks like at this point:
By default, Django displays the str()
of each object. But sometimes it’d be
more helpful if we could display individual fields. To do that, use the
list_display
admin option, which is a tuple of field names to display, as
columns, on the change list page for the object:
class PollAdmin(admin.ModelAdmin):
# ...
list_display = ('question', 'pub_date')
Just for good measure, let’s also include the was_published_recently
custom
method from Tutorial 1:
class PollAdmin(admin.ModelAdmin):
# ...
list_display = ('question', 'pub_date', 'was_published_recently')
Now the poll change list page looks like this:
You can click on the column headers to sort by those values – except in the
case of the was_published_recently
header, because sorting by the output
of an arbitrary method is not supported. Also note that the column header for
was_published_recently
is, by default, the name of the method (with
underscores replaced with spaces), and that each line contains the string
representation of the output.
You can improve that by giving that method (in models.py
) a few
attributes, as follows:
class Poll(models.Model):
# ...
def was_published_recently(self):
return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
was_published_recently.admin_order_field = 'pub_date'
was_published_recently.boolean = True
was_published_recently.short_description = 'Published recently?'
Edit your admin.py file again and add an improvement to the Poll change list page: Filters. Add the
following line to PollAdmin
:
list_filter = ['pub_date']
That adds a “Filter” sidebar that lets people filter the change list by the
pub_date
field:
The type of filter displayed depends on the type of field you’re filtering on.
Because pub_date
is a DateTimeField
,
Django knows to give appropriate filter options: “Any date,” “Today,” “Past 7
days,” “This month,” “This year.”
This is shaping up well. Let’s add some search capability:
search_fields = ['question']
That adds a search box at the top of the change list. When somebody enters
search terms, Django will search the question
field. You can use as many
fields as you’d like – although because it uses a LIKE
query behind the
scenes, keep it reasonable, to keep your database happy.
Finally, because Poll objects have dates, it’d be convenient to be able to drill down by date. Add this line:
date_hierarchy = 'pub_date'
That adds hierarchical navigation, by date, to the top of the change list page. At top level, it displays all available years. Then it drills down to months and, ultimately, days.
Now’s also a good time to note that change lists give you free pagination. The default is to display 100 items per page. Change-list pagination, search boxes, filters, date-hierarchies and column-header-ordering all work together like you think they should.
Clearly, having “Django administration” at the top of each admin page is ridiculous. It’s just placeholder text.
That’s easy to change, though, using Django’s template system. The Django admin is powered by Django itself, and its interfaces use Django’s own template system.
Open your settings file (mysite/settings.py
, remember) and look at the
TEMPLATE_DIRS
setting. TEMPLATE_DIRS
is a tuple of
filesystem directories to check when loading Django templates. It’s a search
path.
By default, TEMPLATE_DIRS
is empty. So, let’s add a line to it, to
tell Django where our templates live:
TEMPLATE_DIRS = (
'/home/my_username/mytemplates', # Change this to your own directory.
)
Now copy the template admin/base_site.html
from within the default Django
admin template directory in the source code of Django itself
(django/contrib/admin/templates
) into an admin
subdirectory of
whichever directory you’re using in TEMPLATE_DIRS
. For example, if
your TEMPLATE_DIRS
includes '/home/my_username/mytemplates'
, as
above, then copy django/contrib/admin/templates/admin/base_site.html
to
/home/my_username/mytemplates/admin/base_site.html
. Don’t forget that
admin
subdirectory.
Then, just edit the file and replace the generic Django text with your own site’s name as you see fit.
This template file contains lots of text like {% block branding %}
and {{ title }}
. The {%
and {{
tags are part of Django’s
template language. When Django renders admin/base_site.html
, this
template language will be evaluated to produce the final HTML page.
Don’t worry if you can’t make any sense of the template right now –
we’ll delve into Django’s templating language in Tutorial 3.
Note that any of Django’s default admin templates can be overridden. To
override a template, just do the same thing you did with base_site.html
–
copy it from the default directory into your custom directory, and make
changes.
Astute readers will ask: But if TEMPLATE_DIRS
was empty by default,
how was Django finding the default admin templates? The answer is that, by
default, Django automatically looks for a templates/
subdirectory within
each app package, for use as a fallback. See the template loader
documentation for full information.
On a similar note, you might want to customize the look and feel of the Django admin index page.
By default, it displays all the apps in INSTALLED_APPS
that have been
registered with the admin application, in alphabetical order. You may want to
make significant changes to the layout. After all, the index is probably the
most important page of the admin, and it should be easy to use.
The template to customize is admin/index.html
. (Do the same as with
admin/base_site.html
in the previous section – copy it from the default
directory to your custom template directory.) Edit the file, and you’ll see it
uses a template variable called app_list
. That variable contains every
installed Django app. Instead of using that, you can hard-code links to
object-specific admin pages in whatever way you think is best. Again,
don’t worry if you can’t understand the template language – we’ll cover that
in more detail in Tutorial 3.
When you’re comfortable with the admin site, read part 3 of this tutorial to start working on public poll views.
Sep 27, 2017