===================================== Writing your first Django app, part 2 ===================================== This tutorial begins where :doc:`Tutorial 1 ` left off. We're continuing the Web-poll application and will focus on Django's automatically-generated admin site. .. admonition:: 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 necessarily intended to be used by site visitors; it's for site managers. Activate the admin site ======================= 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: * Add ``"django.contrib.admin"`` to your :setting:`INSTALLED_APPS` setting. * Run ``python manage.py syncdb``. Since you have added a new application to :setting:`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: .. parsed-literal:: 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.) Start the development server ============================ Let's start the development server and explore the admin site. Recall from Tutorial 1 that you start the development server like so: .. code-block:: bash 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: .. image:: _images/admin01.png :alt: Django admin login screen .. admonition:: 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. Enter the admin site ==================== 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 :ref:`create another one `.) You should see the Django admin index page: .. image:: _images/admin02t.png :alt: Django admin index page You should see a few other types of editable content, including groups, users and sites. These are core features Django ships with by default. Make the poll app modifiable in the admin ========================================= 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. Explore the free admin functionality ==================================== Now that we've registered ``Poll``, Django knows that it should be displayed on the admin index page: .. image:: _images/admin03t.png :alt: Django admin index page, now with polls displayed 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: .. image:: _images/admin04t.png :alt: Polls change list page Click the "What's up?" poll to edit it: .. image:: _images/admin05t.png :alt: Editing form for poll object Things to note here: * The form is automatically generated from the Poll model. * The different model field types (:class:`~django.db.models.DateTimeField`, :class:`~django.db.models.CharField`) correspond to the appropriate HTML input widget. Each type of field knows how to display itself in the Django admin. * Each :class:`~django.db.models.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: * Save -- Saves changes and returns to the change-list page for this type of object. * Save and continue editing -- Saves changes and reloads the admin page for this object. * Save and add another -- Saves changes and loads a new, blank form for this type of object. * Delete -- Displays a delete confirmation page. 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: .. image:: _images/admin06t.png :alt: History page for poll object Customize the admin form ======================== 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: .. image:: _images/admin07.png :alt: Fields have been reordered 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: .. image:: _images/admin08t.png :alt: Form has fieldsets 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']}), ] .. image:: _images/admin09.png :alt: Fieldset is initially collapsed Adding related objects ====================== OK, we have our Poll admin page. But a ``Poll`` has multiple ``Choices``, and the admin page doesn't display choices. Yet. There are two ways to solve this problem. The first is to register ``Choice`` with the admin just as we did with ``Poll``. That's easy:: from polls.models import Choice admin.site.register(Choice) Now "Choices" is an available option in the Django admin. The "Add choice" form looks like this: .. image:: _images/admin10.png :alt: Choice admin page In that form, the "Poll" field is a select box containing every poll in the database. Django knows that a :class:`~django.db.models.ForeignKey` should be represented in the admin as a ``