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    1 ===================================== 
    2 Writing your first Django app, part 2 
    3 ===================================== 
    4  
    5 This tutorial begins where `Tutorial 1`_ left off. We're continuing the Web-poll 
    6 application and will focus on Django's automatically-generated admin site. 
    7  
    8 .. _Tutorial 1: ../tutorial01/ 
    9  
    10 .. admonition:: Philosophy 
    11  
    12     Generating admin sites for your staff or clients to add, change and delete 
    13     content is tedious work that doesn't require much creativity. For that reason, 
    14     Django entirely automates creation of admin interfaces for models. 
    15  
    16     Django was written in a newsroom environment, with a very clear separation 
    17     between "content publishers" and the "public" site. Site managers use the 
    18     system to add news stories, events, sports scores, etc., and that content is 
    19     displayed on the public site. Django solves the problem of creating a unified 
    20     interface for site administrators to edit content. 
    21  
    22     The admin isn't necessarily intended to be used by site visitors; it's for site 
    23     managers. 
    24  
    25 Activate the admin site 
    26 ======================= 
    27  
    28 The Django admin site is not activated by default -- it's an opt-in thing. To 
    29 activate the admin site for your installation, do these three things: 
    30  
    31     * Add ``"django.contrib.admin"`` to your ``INSTALLED_APPS`` setting. 
    32     * Run ``python manage.py syncdb``. Since you have added a new application 
    33       to ``INSTALLED_APPS``, the database tables need to be updated. 
    34     * Edit your ``mysite/urls.py`` file and uncomment the line below 
    35       "Uncomment this for admin:". This file is a URLconf; we'll dig into 
    36       URLconfs in the next tutorial. For now, all you need to know is that it 
    37       maps URL roots to applications. 
    38  
    39 Start the development server 
    40 ============================ 
    41  
    42 Let's start the development server and explore the admin site. 
    43  
    44 Recall from Tutorial 1 that you start the development server like so:: 
    45  
    46     python manage.py runserver 
    47  
    48 Now, open a Web browser and go to "/admin/" on your local domain -- e.g., 
    49 http://127.0.0.1:8000/admin/. You should see the admin's login screen: 
    50  
    51 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin01.png 
    52    :alt: Django admin login screen 
    53  
    54 Enter the admin site 
    55 ==================== 
    56  
    57 Now, try logging in. (You created a superuser account in the first part of this 
    58 tutorial, remember?) You should see the Django admin index page: 
    59  
    60 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin02t.png 
    61    :alt: Django admin index page 
    62    :target: http://media.djangoproject.com/img/doc/tutorial/admin02.png 
    63  
    64 You should see a few other types of editable content, including groups, users 
    65 and sites. These are core features Django ships with by default. 
    66  
    67 .. _"I can't log in" questions: ../faq/#the-admin-site 
    68  
    69 Make the poll app modifiable in the admin 
    70 ========================================= 
    71  
    72 But where's our poll app? It's not displayed on the admin index page. 
    73  
    74 Just one thing to do: We need to specify in the ``Poll`` model that ``Poll`` 
    75 objects have an admin interface. Edit the ``mysite/polls/models.py`` file and 
    76 make the following change to add an inner ``Admin`` class:: 
    77  
    78     class Poll(models.Model): 
    79         # ... 
    80         class Admin: 
    81             pass 
    82  
    83 The ``class Admin`` will contain all the settings that control how this model 
    84 appears in the Django admin.  All the settings are optional, however, so 
    85 creating an empty class means "give this object an admin interface using 
    86 all the default options." 
    87  
    88 Now reload the Django admin page to see your changes. Note that you don't have 
    89 to restart the development server -- the server will auto-reload your project, 
    90 so any modifications code will be seen immediately in your browser. 
    91  
    92 Explore the free admin functionality 
    93 ==================================== 
    94  
    95 Now that ``Poll`` has the inner ``Admin`` class, Django knows that it should be 
    96 displayed on the admin index page: 
    97  
    98 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin03t.png 
    99    :alt: Django admin index page, now with polls displayed 
    100    :target: http://media.djangoproject.com/img/doc/tutorial/admin03.png 
    101  
    102 Click "Polls." Now you're at the "change list" page for polls. This page 
    103 displays all the polls in the database and lets you choose one to change it. 
    104 There's the "What's up?" poll we created in the first tutorial: 
    105  
    106 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin04t.png 
    107    :alt: Polls change list page 
    108    :target: http://media.djangoproject.com/img/doc/tutorial/admin04.png 
    109  
    110 Click the "What's up?" poll to edit it: 
    111  
    112 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin05t.png 
    113    :alt: Editing form for poll object 
    114    :target: http://media.djangoproject.com/img/doc/tutorial/admin05.png 
    115  
    116 Things to note here: 
    117  
    118 * The form is automatically generated from the Poll model. 
    119 * The different model field types (``models.DateTimeField``, ``models.CharField``) 
    120   correspond to the appropriate HTML input widget. Each type of field knows 
    121   how to display itself in the Django admin. 
    122 * Each ``DateTimeField`` gets free JavaScript shortcuts. Dates get a "Today" 
    123   shortcut and calendar popup, and times get a "Now" shortcut and a convenient 
    124   popup that lists commonly entered times. 
    125  
    126 The bottom part of the page gives you a couple of options: 
    127  
    128 * Save -- Saves changes and returns to the change-list page for this type of 
    129   object. 
    130 * Save and continue editing -- Saves changes and reloads the admin page for 
    131   this object. 
    132 * Save and add another -- Saves changes and loads a new, blank form for this 
    133   type of object. 
    134 * Delete -- Displays a delete confirmation page. 
    135  
    136 Change the "Date published" by clicking the "Today" and "Now" shortcuts. Then 
    137 click "Save and continue editing." Then click "History" in the upper right. 
    138 You'll see a page listing all changes made to this object via the Django admin, 
    139 with the timestamp and username of the person who made the change: 
    140  
    141 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin06t.png 
    142    :alt: History page for poll object 
    143    :target: http://media.djangoproject.com/img/doc/tutorial/admin06.png 
    144  
    145 Customize the admin form 
    146 ======================== 
    147  
    148 Take a few minutes to marvel at all the code you didn't have to write. 
    149  
    150 Let's customize this a bit. We can reorder the fields by explicitly adding a 
    151 ``fields`` parameter to ``Admin``:: 
    152  
    153         class Admin: 
    154             fields = ( 
    155                 (None, {'fields': ('pub_date', 'question')}), 
    156             ) 
    157  
    158 That made the "Publication date" show up first instead of second: 
    159  
    160 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin07.png 
    161    :alt: Fields have been reordered 
    162  
    163 This isn't impressive with only two fields, but for admin forms with dozens 
    164 of fields, choosing an intuitive order is an important usability detail. 
    165  
    166 And speaking of forms with dozens of fields, you might want to split the form 
    167 up into fieldsets:: 
    168  
    169         class Admin: 
    170             fields = ( 
    171                 (None, {'fields': ('question',)}), 
    172                 ('Date information', {'fields': ('pub_date',)}), 
    173             ) 
    174  
    175 The first element of each tuple in ``fields`` is the title of the fieldset. 
    176 Here's what our form looks like now: 
    177  
    178 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin08t.png 
    179    :alt: Form has fieldsets now 
    180    :target: http://media.djangoproject.com/img/doc/tutorial/admin08.png 
    181  
    182 You can assign arbitrary HTML classes to each fieldset. Django provides a 
    183 ``"collapse"`` class that displays a particular fieldset initially collapsed. 
    184 This is useful when you have a long form that contains a number of fields that 
    185 aren't commonly used:: 
    186  
    187         class Admin: 
    188             fields = ( 
    189                 (None, {'fields': ('question',)}), 
    190                 ('Date information', {'fields': ('pub_date',), 'classes': 'collapse'}), 
    191             ) 
    192  
    193 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin09.png 
    194    :alt: Fieldset is initially collapsed 
    195  
    196 Adding related objects 
    197 ====================== 
    198  
    199 OK, we have our Poll admin page. But a ``Poll`` has multiple ``Choices``, and 
    200 the admin page doesn't display choices. 
    201  
    202 Yet. 
    203  
    204 There are two ways to solve this problem. The first is to give the ``Choice`` 
    205 model its own inner ``Admin`` class, just as we did with ``Poll``. Here's what 
    206 that would look like:: 
    207  
    208     class Choice(models.Model): 
    209         # ... 
    210         class Admin: 
    211             pass 
    212  
    213 Now "Choices" is an available option in the Django admin. The "Add choice" form 
    214 looks like this: 
    215  
    216 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin10.png 
    217    :alt: Choice admin page 
    218  
    219 In that form, the "Poll" field is a select box containing every poll in the 
    220 database. Django knows that a ``ForeignKey`` should be represented in the admin 
    221 as a ``<select>`` box. In our case, only one poll exists at this point. 
    222  
    223 Also note the "Add Another" link next to "Poll." Every object with a ForeignKey 
    224 relationship to another gets this for free. When you click "Add Another," you'll 
    225 get a popup window with the "Add poll" form. If you add a poll in that window 
    226 and click "Save," Django will save the poll to the database and dynamically add 
    227 it as the selected choice on the "Add choice" form you're looking at. 
    228  
    229 But, really, this is an inefficient way of adding Choice objects to the system. 
    230 It'd be better if you could add a bunch of Choices directly when you create the 
    231 Poll object. Let's make that happen. 
    232  
    233 Remove the ``Admin`` for the Choice model. Then, edit the ``ForeignKey(Poll)`` 
    234 field like so:: 
    235  
    236     poll = models.ForeignKey(Poll, edit_inline=models.STACKED, num_in_admin=3) 
    237  
    238 This tells Django: "Choice objects are edited on the Poll admin page. By 
    239 default, provide enough fields for 3 Choices." 
    240  
    241 Then change the other fields in ``Choice`` to give them ``core=True``:: 
    242  
    243     choice = models.CharField(max_length=200, core=True) 
    244     votes = models.IntegerField(core=True) 
    245  
    246 This tells Django: "When you edit a Choice on the Poll admin page, the 'choice' 
    247 and 'votes' fields are required. The presence of at least one of them signifies 
    248 the addition of a new Choice object, and clearing both of them signifies the 
    249 deletion of that existing Choice object." 
    250  
    251 Load the "Add poll" page to see how that looks: 
    252  
    253 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin11t.png 
    254    :alt: Add poll page now has choices on it 
    255    :target: http://media.djangoproject.com/img/doc/tutorial/admin11.png 
    256  
    257 It works like this: There are three slots for related Choices -- as specified 
    258 by ``num_in_admin`` -- but each time you come back to the "Change" page for an 
    259 already-created object, you get one extra slot. (This means there's no 
    260 hard-coded limit on how many related objects can be added.) If you wanted space 
    261 for three extra Choices each time you changed the poll, you'd use 
    262 ``num_extra_on_change=3``. 
    263  
    264 One small problem, though. It takes a lot of screen space to display all the 
    265 fields for entering related Choice objects. For that reason, Django offers an 
    266 alternate way of displaying inline related objects:: 
    267  
    268     poll = models.ForeignKey(Poll, edit_inline=models.TABULAR, num_in_admin=3) 
    269  
    270 With that ``edit_inline=models.TABULAR`` (instead of ``models.STACKED``), the 
    271 related objects are displayed in a more compact, table-based format: 
    272  
    273 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin12.png 
    274    :alt: Add poll page now has more compact choices 
    275  
    276 Customize the admin change list 
    277 =============================== 
    278  
    279 Now that the Poll admin page is looking good, let's make some tweaks to the 
    280 "change list" page -- the one that displays all the polls in the system. 
    281  
    282 Here's what it looks like at this point: 
    283  
    284 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin04t.png 
    285    :alt: Polls change list page 
    286    :target: http://media.djangoproject.com/img/doc/tutorial/admin04.png 
    287  
    288 By default, Django displays the ``str()`` of each object. But sometimes it'd 
    289 be more helpful if we could display individual fields. To do that, use the 
    290 ``list_display`` option, which is a tuple of field names to display, as columns, 
    291 on the change list page for the object:: 
    292  
    293     class Poll(models.Model): 
    294         # ... 
    295         class Admin: 
    296             # ... 
    297             list_display = ('question', 'pub_date') 
    298  
    299 Just for good measure, let's also include the ``was_published_today`` custom 
    300 method from Tutorial 1:: 
    301  
    302     list_display = ('question', 'pub_date', 'was_published_today') 
    303  
    304 Now the poll change list page looks like this: 
    305  
    306 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin13t.png 
    307    :alt: Polls change list page, updated 
    308    :target: http://media.djangoproject.com/img/doc/tutorial/admin13.png 
    309  
    310 You can click on the column headers to sort by those values -- except in the 
    311 case of the ``was_published_today`` header, because sorting by the output of 
    312 an arbitrary method is not supported. Also note that the column header for 
    313 ``was_published_today`` is, by default, the name of the method (with 
    314 underscores replaced with spaces). But you can change that by giving that 
    315 method a ``short_description`` attribute:: 
    316  
    317     def was_published_today(self): 
    318         return self.pub_date.date() == datetime.date.today() 
    319     was_published_today.short_description = 'Published today?' 
    320  
    321  
    322 Let's add another improvement to the Poll change list page: Filters. Add the 
    323 following line to ``Poll.Admin``:: 
    324  
    325     list_filter = ['pub_date'] 
    326  
    327 That adds a "Filter" sidebar that lets people filter the change list by the 
    328 ``pub_date`` field: 
    329  
    330 .. image:: http://media.djangoproject.com/img/doc/tutorial/admin14t.png 
    331    :alt: Polls change list page, updated 
    332    :target: http://media.djangoproject.com/img/doc/tutorial/admin14.png 
    333  
    334 The type of filter displayed depends on the type of field you're filtering on. 
    335 Because ``pub_date`` is a DateTimeField, Django knows to give the default 
    336 filter options for DateTimeFields: "Any date," "Today," "Past 7 days," 
    337 "This month," "This year." 
    338  
    339 This is shaping up well. Let's add some search capability:: 
    340  
    341     search_fields = ['question'] 
    342  
    343 That adds a search box at the top of the change list. When somebody enters 
    344 search terms, Django will search the ``question`` field. You can use as many 
    345 fields as you'd like -- although because it uses a ``LIKE`` query behind the 
    346 scenes, keep it reasonable, to keep your database happy. 
    347  
    348 Finally, because Poll objects have dates, it'd be convenient to be able to 
    349 drill down by date. Add this line:: 
    350  
    351     date_hierarchy = 'pub_date' 
    352  
    353 That adds hierarchical navigation, by date, to the top of the change list page. 
    354 At top level, it displays all available years. Then it drills down to months 
    355 and, ultimately, days. 
    356  
    357 Now's also a good time to note that change lists give you free pagination. The 
    358 default is to display 50 items per page. Change-list pagination, search boxes, 
    359 filters, date-hierarchies and column-header-ordering all work together like you 
    360 think they should. 
    361  
    362 Customize the admin look and feel 
    363 ================================= 
    364  
    365 Clearly, having "Django administration" at the top of each admin page is 
    366 ridiculous. It's just placeholder text. 
    367  
    368 That's easy to change, though, using Django's template system. The Django admin 
    369 is powered by Django itself, and its interfaces use Django's own template 
    370 system. (How meta!) 
    371  
    372 Open your settings file (``mysite/settings.py``, remember) and look at the 
    373 ``TEMPLATE_DIRS`` setting. ``TEMPLATE_DIRS`` is a tuple of filesystem 
    374 directories to check when loading Django templates. It's a search path. 
    375  
    376 By default, ``TEMPLATE_DIRS`` is empty. So, let's add a line to it, to tell 
    377 Django where our templates live:: 
    378  
    379     TEMPLATE_DIRS = ( 
    380         "/home/my_username/mytemplates", # Change this to your own directory. 
    381     ) 
    382  
    383 Now copy the template ``admin/base_site.html`` from within the default Django 
    384 admin template directory (``django/contrib/admin/templates``) into an ``admin`` 
    385 subdirectory of whichever directory you're using in ``TEMPLATE_DIRS``. For 
    386 example, if your ``TEMPLATE_DIRS`` includes ``"/home/my_username/mytemplates"``, 
    387 as above, then copy ``django/contrib/admin/templates/admin/base_site.html`` to 
    388 ``/home/my_username/mytemplates/admin/base_site.html``. Don't forget that 
    389 ``admin`` subdirectory. 
    390  
    391 Then, just edit the file and replace the generic Django text with your own 
    392 site's name as you see fit. 
    393  
    394 Note that any of Django's default admin templates can be overridden. To 
    395 override a template, just do the same thing you did with ``base_site.html`` -- 
    396 copy it from the default directory into your custom directory, and make 
    397 changes. 
    398  
    399 Astute readers will ask: But if ``TEMPLATE_DIRS`` was empty by default, how was 
    400 Django finding the default admin templates? The answer is that, by default, 
    401 Django automatically looks for a ``templates/`` subdirectory within each app 
    402 package, for use as a fallback. See the `loader types documentation`_ for full 
    403 information. 
    404  
    405 .. _loader types documentation: ../templates_python/#loader-types 
    406  
    407 Customize the admin index page 
    408 ============================== 
    409  
    410 On a similar note, you might want to customize the look and feel of the Django 
    411 admin index page. 
    412  
    413 By default, it displays all available apps, according to your ``INSTALLED_APPS`` 
    414 setting. But the order in which it displays things is random, and you may want 
    415 to make significant changes to the layout. After all, the index is probably the 
    416 most important page of the admin, and it should be easy to use. 
    417  
    418 The template to customize is ``admin/index.html``. (Do the same as with 
    419 ``admin/base_site.html`` in the previous section -- copy it from the default 
    420 directory to your custom template directory.) Edit the file, and you'll see it 
    421 uses a template tag called ``{% get_admin_app_list as app_list %}``. That's the 
    422 magic that retrieves every installed Django app. Instead of using that, you can 
    423 hard-code links to object-specific admin pages in whatever way you think is 
    424 best. 
    425  
    426 Django offers another shortcut in this department. Run the command 
    427 ``python manage.py adminindex polls`` to get a chunk of template code for 
    428 inclusion in the admin index template. It's a useful starting point. 
    429  
    430 For full details on customizing the look and feel of the Django admin site in 
    431 general, see the `Django admin CSS guide`_. 
    432  
    433 When you're comfortable with the admin site, read `part 3 of this tutorial`_ to 
    434 start working on public poll views. 
    435  
    436 .. _Django admin CSS guide: ../admin_css/ 
    437 .. _part 3 of this tutorial: ../tutorial03/