#

## Django documentation

# Writing your first Django app, part 2

By Adrian Holovaty <holovaty@gmail.com>

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 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 `INSTALLED_APPS` setting.
> - Run the command `django-admin.py install admin`. This will create an extra database table that the admin needs.
> - Edit your `myproject/urls.py` file and uncomment the line below "Uncomment this for admin:". 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.

## Create a user account

Run the following command to create a superuser account for your admin site:

    django-admin.py createsuperuser --settings=myproject.settings

The script will prompt you for a username, e-mail address and password (twice).

## Start the development server

To make things easy, Django comes with a pure-Python Web server that builds on the BaseHTTPServer included in Python's standard library. Let's start the server and explore the admin site.

Just run the following command to start the server:

    django-admin.py runserver --settings=myproject.settings

It'll start a Web server running locally -- on port 8000, by default. If you want to change the server's port, pass it as a command-line argument:

    django-admin.py runserver 8080 --settings=myproject.settings

DON'T use this server in anything resembling a production environment. It's intended only for use while developing.

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:

## Enter the admin site

Now, try logging in. You should see the Django admin index page:

By default, you should see two types of editable content: groups and users. 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 specify in the `polls.Poll` model that Poll objects have an admin interface. Edit the `myproject/apps/polls/models/polls.py` file and make the following change to add an inner `META` class with an `admin` attribute:

    class Poll(meta.Model):
        # ...
        class META:
            admin = meta.Admin()

The `class META` contains all non-field metadata about this model.

Now reload the Django admin page to see your changes. Note that you don't have to restart the development server -- it auto-reloads code.

## Explore the free admin functionality

Now that `Poll` has the `admin` attribute, 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:

- The form is automatically generated from the Poll model.
- The different model field types (`meta.DateTimeField`, `meta.CharField`) correspond to the appropriate HTML input widget. Each type of field knows how to display itself in the Django admin.
- Each `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:

## Customize the admin form

Take a few minutes to marvel at all the code you didn't have to write.

Let's customize this a bit. We can reorder the fields by explicitly adding a `fields` parameter to `meta.Admin`:

    admin = meta.Admin(
        fields = (
            (None, {'fields': ('pub_date', 'question')}),
        ),
    )

That made the "Publication date" show up first instead of second:

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:

    admin = meta.Admin(
        fields = (
            (None, {'fields': ('question',)}),
            ('Date information', {'fields': ('pub_date',)}),
        ),
    )

The first element of each tuple in `fields` 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:

    admin = meta.Admin(
        fields = (
            (None, {'fields': ('question',)}),
            ('Date information', {'fields': ('pub_date',), 'classes': 'collapse'}),
        ),
    )

## 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.

In this case, there are two ways to solve this problem. The first is to give the `Choice` model its own `admin` attribute, just as we did with `Poll`. Here's what that would look like:

    class Choice(meta.Model):
        # ...
        class META:
            admin = meta.Admin()

Now "Choices" is an available option in the Django admin. The "Add choice" form looks like this:

In that form, the "Poll" field is a select box containing every poll in the database. In our case, only one poll exists at this point.

Also note the "Add Another" link next to "Poll." Every object with a ForeignKey relationship to another gets this for free. When you click "Add Another," you'll get a popup window with the "Add poll" form. If you add a poll in that window and click "Save," Django will save the poll to the database and dynamically add it as the selected choice on the "Add choice" form you're looking at.

But, really, this is an inefficient way of adding Choice objects to the system. It'd be better if you could add a bunch of Choices directly when you create the Poll object. Let's make that happen.

Remove the `admin` for the Choice model. Then, edit the `ForeignKey(Poll)` field like so:

    poll = meta.ForeignKey(Poll, edit_inline=meta.STACKED, num_in_admin=3)

This tells Django: "Choice objects are edited on the Poll admin page. By default, provide enough fields for 3 Choices."

Then change the other fields in `Choice` to give them `core=True`:

    choice = meta.CharField(maxlength=200, core=True)
    votes = meta.IntegerField(core=True)

This tells Django: "When you edit a Choice on the Poll admin page, the 'choice' and 'votes' fields are required. The presence of at least one of them signifies the addition of a new Choice object, and clearing both of them signifies the deletion of that existing Choice object."

Load the "Add poll" page to see how that looks:

It works like this: There are three slots for related Choices -- as specified by `num_in_admin` -- but each time you come back to the "Change" page for an already-created object, you get one extra slot. (This means there's no hard-coded limit on how many related objects can be added.) If you wanted space for three extra Choices each time you changed the poll, you'd use `num_extra_on_change=3`.

One small problem, though. It takes a lot of screen space to display all the fields for entering related Choice objects. For that reason, Django offers an alternate way of displaying inline related objects:

    poll = meta.ForeignKey(Poll, edit_inline=meta.TABULAR, num_in_admin=3)

With that `edit_inline=meta.TABULAR` (instead of `meta.STACKED`), the related objects are displayed in a more compact, table-based format:

## Customize the admin change list

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 `repr()` of each object. But it'd be more helpful if we could display individual fields. To do that, use the `list_display` option, which is a tuple of field names to display, as columns, on the change list page for the object:

    class Poll(meta.Model):
        # ...
        class META:
            admin = meta.Admin(
                # ...
                list_display = ('question', 'pub_date'),
            )

Just for good measure, let's also include the `was_published_today` custom method from Tutorial 1:

    list_display = ('question', 'pub_date', 'was_published_today'),

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_today` header, because sorting by the output of an arbitrary method is not supported. Also note that the column header for `was_published_today` is, by default, the name of the method (with underscores replaced with spaces). But you can change that by giving that method a `short_description` attribute:

    def was_published_today(self):
        return self.pub_date.date() == datetime.date.today()
    was_published_today.short_description = 'Published today?'

Let's add another improvement to the Poll change list page: Filters. Add the following line to `Poll.admin`:

    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 the default filter options for DateTimeFields: "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 50 items per page. Change-list pagination, search boxes, filters, date-hierarchies and column-header-ordering all work together like you think they should.

## Customize the admin look and feel

Clearly, having "Django administration" and "example.com" 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. (How meta!)

Open your settings file (`myproject/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/mytemplates", # Change this to your own directory.
    )

Now copy the template `admin/base_site.html` from within the default Django admin template directory (`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/mytemplates"`, as above, then copy `django/contrib/admin/templates/admin/base_site.html` to `/home/mytemplates/admin/base_site.html`.

Then, just edit the file and replace the generic Django text with your own site's name and URL as you see fit.

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 loader types documentation for full information.

## Customize the admin index page

On a similar note, you might want to customize the look and feel of the Django admin index page.

By default, it displays all available apps, according to your `INSTALLED_APPS` setting. But the order in which it displays things is random, and 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 tag called `{% get_admin_app_list as app_list %}`. That's the magic that retrieves 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.

Django offers another shortcut in this department. Run the command `django-admin.py adminindex polls` to get a chunk of template code for inclusion in the admin index template. It's a useful starting point.

For full details on customizing the look and feel of the Django admin site in general, see the Django admin CSS guide.

When you're comfortable with the admin site, read part 3 of this tutorial to start working on public poll views.

## Comments

### gunahl July 19, 2005 at 2:53 a.m.

First all, great article! Very inclusive and to the point!
Could you please post the complete source at the end of each tutorial? Something like www.ibm.com/developerworks articles. This would add clearity, as code is added and removed during the article.

### dzc July 22, 2005 at 12:42 a.m.

Is there a timezone setting somewhere? In the python interpreter, datetime.date.today() gives "datetime.date(2005, 7, 21)", however I've defined was_published_today as:

def was_published_today(self):
print self.pub_date.date() , datetime.date.today()
return self.pub_date.date() == datetime.date.today()

and this gives:

2005-07-21 2005-07-22

in my output. It is indeed the 22nd GMT, but still the 21st in PST. I'm using the new sqlite3 backend on Linux.

### Lada July 22, 2005 at 2:19 p.m.

Amazing.
I have a webhosting provider who hosts my Python scripts.And would like
to have Django on the server as well.
Can I install that by myself or I must be a server administrator to
do so? Thanks for reply
python@hope.cz

### Diez B. Roggisch July 23, 2005 at 6:22 a.m.

Great Stuff!

But I encountered two little pitfalls that you should emphasize more here:

1) The --settings parameter changed it's suffix from .main to .admin - make sure the reader gets that, and when coming from tutorial 1, doesn't keep a DJANGO_SETTINGS_MODULE environment variable around.

2) The url to visit is http://localhost:8000/admin/ - I missed the admin part first and got a nasty stacktrace instead. Try and emphasize ths more, too.

### Jorge Rpo July 26, 2005 at 10:37 p.m.

In editing is there a CANCEL option besides
* Save
* Save and continue editing
* Save and add another
* Delete
??

### dp_wiz July 27, 2005 at 7:02 p.m.

Here is another translation into russian:
http://aenor.ru/wiz/django/tutorial_2

have fun (:

### GrumpySimon August 18, 2005 at 12:33 a.m.

Is it possible to use a relative path for the templates directory (ie: $project/templates? )

### stanko September 1, 2005 at 12:25 p.m.

if I have a custom method and want to return a link
such as '<a href="http://www.yahoo.com">yahoo</a>'
it will return yahoo string but not a link

### harmless September 2, 2005 at 1:52 p.m.

I made my Polll and Choice classes __repr__ output a (to me) more python-like '"<Poll: %s>" % self.question'; but it seems that the admin system doesn't do html escaping on these strings, so my polls never showed up properly until I changed it back. I'm putting this here because I haven't found the bug tracker yet.

### xanthian September 4, 2005 at 5:22 a.m.

Seems that in the "runserver" commandline described above, the server is only available on the localhost (via loopback). If you are viewing from a separate machine, try adding the IP address of the serving machine in the form <ip_address>:8000 (or other portnumber) to the django-admin.py commandline.

Django rocks!

### Qball September 12, 2005 at 10:25 a.m.

If you get the error:

Unhandled exception in thread started by <function inner_run at 0x00B2BAB0>
(...)
File "C:\Program Files\Python2.4.1\lib\site-packages\projDjangoQuentin\apps\po
lls\models\polls.py", line 14
class META:
SyntaxError: invalid syntax

,check you have tabs and not spaces in the code (cut&paste from this tutorial)!!!

### Levi Cook September 20, 2005 at 8:28 p.m.

The default for TEMPLATE_DIRS is something like this (depending what version of python your running):

TEMPLATE_DIRS = ( r'/usr/lib/python2.4/site-packages/django/conf/admin_templates',
# Put strings here, like "/home/html/django_templates".
)

I'm routinely updating it to the following:

from os import path
MODULE_HOME = path.dirname(path.abspath(__file__))
TEMPLATE_DIRS = (
path.join(MODULE_HOME, 'admin_templates'), r'/usr/lib/python2.4/site-packages/django/conf/admin_templates',
)

I think this addresses GrumpySimon's question on using relative directories. The main upshot, for me is being able to grab my entire application by copying a directory. Fumbling around for external dependencies at deploy time is simply embarrasing :)

### samuel September 25, 2005 at 4:23 a.m.

When you wrote: DON'T use this server in anything resembling a production environment. It's intended only for use while developing.

Did you mean that for production site it should be used by apache and mod_python for example ?

### Adrian Holovaty September 25, 2005 at 1:10 p.m.

Samuel: Yes.

### pterk October 4, 2005 at 11:17 a.m.

I think the comment

(Note: You can use either "myproject.settings.main" or "myproject.settings.admin" here. They both reference the same database.)

at the start of this tutorial should be removed? I was stuborn enough to not even try change the settings until someone on irc kindly suggested that to me and then it did work...

### pterk October 4, 2005 at 11:41 a.m.

Well, maybe not... I should perhaps have read on a bit...

Maybe the Note after the login 'screenshot' should be moved up for dummies like myself how don't scroll on when they have a problem...

### joerg November 3, 2005 at 3:53 p.m.

I get an database error:

django-admin.py install admin
Error: admin couldn't be installed. Possible reasons:
* The database isn't running or isn't configured correctly.
* At least one of the database tables already exists.
* The SQL was invalid.
Hint: Look at the output of 'django-admin.py sqlall admin'. That's the SQL this command wasn't able to run.
The full error: ERROR: Relation »auth_users« does not exist

CREATE TABLE django_admin_log (
id serial NOT NULL PRIMARY KEY,
action_time timestamp with time zone NOT NULL,
user_id integer NOT NULL REFERENCES auth_users (id),
content_type_id integer NULL REFERENCES content_types (id),
object_id text NULL,
object_repr varchar(200) NOT NULL,
action_flag smallint CHECK (action_flag >= 0) NOT NULL,
change_message text NOT NULL
);

how do I create auth_users?

### Adrian Holovaty November 3, 2005 at 6:25 p.m.

joerg: The command "django-admin.py init" (from tutorial 1) creates the auth_users table.

### Cheng Zhang November 10, 2005 at 11:08 a.m.

In section "Activate the admin site", "Edit your myproject.urls file and uncomment the line below "Uncomment this for admin:". 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."
Maybe I missed something, but I couldn't find any reference of myproject.urls in part 1. So it's quite confused to me where to look it up, and what this myproject.urls file should contain.

### Cheng Zhang November 10, 2005 at 11:37 a.m.

Regarding my above comment, after proceeding to part 3, now I understand that the "myproject.urls file" is indeed the module myproject.urls, which is actually the "urls.py" in myproject folder. I still feel the way that the document is describing is a bit confusing though.

### Jeroen Ruigrok van der Werven November 11, 2005 at 4:14 p.m.

In the section 'Customize the admin form', make sure you tell the reader that you are changing this code in apps/polls/models/polls.py, it might be confusing otherwise.

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