mirror of
https://github.com/django/django.git
synced 2025-10-31 01:25:32 +00:00
418 lines
15 KiB
Plaintext
418 lines
15 KiB
Plaintext
====================================
|
||
Writing custom django-admin commands
|
||
====================================
|
||
|
||
.. module:: django.core.management
|
||
|
||
Applications can register their own actions with ``manage.py``. For example,
|
||
you might want to add a ``manage.py`` action for a Django app that you're
|
||
distributing. In this document, we will be building a custom ``closepoll``
|
||
command for the ``polls`` application from the
|
||
:doc:`tutorial</intro/tutorial01>`.
|
||
|
||
To do this, just add a ``management/commands`` directory to the application.
|
||
Django will register a ``manage.py`` command for each Python module in that
|
||
directory whose name doesn't begin with an underscore. For example::
|
||
|
||
polls/
|
||
__init__.py
|
||
models.py
|
||
management/
|
||
__init__.py
|
||
commands/
|
||
__init__.py
|
||
_private.py
|
||
closepoll.py
|
||
tests.py
|
||
views.py
|
||
|
||
In this example, the ``closepoll`` command will be made available to any project
|
||
that includes the ``polls`` application in :setting:`INSTALLED_APPS`.
|
||
|
||
The ``_private.py`` module will not be available as a management command.
|
||
|
||
The ``closepoll.py`` module has only one requirement -- it must define a class
|
||
``Command`` that extends :class:`BaseCommand` or one of its
|
||
:ref:`subclasses<ref-basecommand-subclasses>`.
|
||
|
||
.. admonition:: Standalone scripts
|
||
|
||
Custom management commands are especially useful for running standalone
|
||
scripts or for scripts that are periodically executed from the UNIX crontab
|
||
or from Windows scheduled tasks control panel.
|
||
|
||
To implement the command, edit ``polls/management/commands/closepoll.py`` to
|
||
look like this:
|
||
|
||
.. code-block:: python
|
||
|
||
from django.core.management.base import BaseCommand, CommandError
|
||
from polls.models import Poll
|
||
|
||
class Command(BaseCommand):
|
||
args = '<poll_id poll_id ...>'
|
||
help = 'Closes the specified poll for voting'
|
||
|
||
def handle(self, *args, **options):
|
||
for poll_id in args:
|
||
try:
|
||
poll = Poll.objects.get(pk=int(poll_id))
|
||
except Poll.DoesNotExist:
|
||
raise CommandError('Poll "%s" does not exist' % poll_id)
|
||
|
||
poll.opened = False
|
||
poll.save()
|
||
|
||
self.stdout.write('Successfully closed poll "%s"' % poll_id)
|
||
|
||
.. _management-commands-output:
|
||
|
||
.. note::
|
||
When you are using management commands and wish to provide console
|
||
output, you should write to ``self.stdout`` and ``self.stderr``,
|
||
instead of printing to ``stdout`` and ``stderr`` directly. By
|
||
using these proxies, it becomes much easier to test your custom
|
||
command. Note also that you don't need to end messages with a newline
|
||
character, it will be added automatically, unless you specify the ``ending``
|
||
parameter::
|
||
|
||
self.stdout.write("Unterminated line", ending='')
|
||
|
||
The new custom command can be called using ``python manage.py closepoll
|
||
<poll_id>``.
|
||
|
||
The ``handle()`` method takes zero or more ``poll_ids`` and sets ``poll.opened``
|
||
to ``False`` for each one. If the user referenced any nonexistent polls, a
|
||
:class:`CommandError` is raised. The ``poll.opened`` attribute does not exist
|
||
in the :doc:`tutorial</intro/tutorial01>` and was added to
|
||
``polls.models.Poll`` for this example.
|
||
|
||
The same ``closepoll`` could be easily modified to delete a given poll instead
|
||
of closing it by accepting additional command line options. These custom options
|
||
must be added to :attr:`~BaseCommand.option_list` like this:
|
||
|
||
.. code-block:: python
|
||
|
||
from optparse import make_option
|
||
|
||
class Command(BaseCommand):
|
||
option_list = BaseCommand.option_list + (
|
||
make_option('--delete',
|
||
action='store_true',
|
||
dest='delete',
|
||
default=False,
|
||
help='Delete poll instead of closing it'),
|
||
)
|
||
|
||
def handle(self, *args, **options):
|
||
# ...
|
||
if options['delete']:
|
||
poll.delete()
|
||
# ...
|
||
|
||
The option (``delete`` in our example) is available in the options dict
|
||
parameter of the handle method. See the :py:mod:`optparse` Python documentation
|
||
for more about ``make_option`` usage.
|
||
|
||
In addition to being able to add custom command line options, all
|
||
:doc:`management commands</ref/django-admin>` can accept some
|
||
default options such as :djadminopt:`--verbosity` and :djadminopt:`--traceback`.
|
||
|
||
.. _management-commands-and-locales:
|
||
|
||
Management commands and locales
|
||
===============================
|
||
|
||
By default, the :meth:`BaseCommand.execute` method sets the hardcoded 'en-us'
|
||
locale because some commands shipped with Django perform several tasks
|
||
(for example, user-facing content rendering and database population) that
|
||
require a system-neutral string language (for which we use 'en-us').
|
||
|
||
If, for some reason, your custom management command needs to use a fixed locale
|
||
different from 'en-us', you should manually activate and deactivate it in your
|
||
:meth:`~BaseCommand.handle` or :meth:`~NoArgsCommand.handle_noargs` method using
|
||
the functions provided by the I18N support code:
|
||
|
||
.. code-block:: python
|
||
|
||
from django.core.management.base import BaseCommand, CommandError
|
||
from django.utils import translation
|
||
|
||
class Command(BaseCommand):
|
||
...
|
||
can_import_settings = True
|
||
|
||
def handle(self, *args, **options):
|
||
|
||
# Activate a fixed locale, e.g. Russian
|
||
translation.activate('ru')
|
||
|
||
# Or you can activate the LANGUAGE_CODE # chosen in the settings:
|
||
#
|
||
#from django.conf import settings
|
||
#translation.activate(settings.LANGUAGE_CODE)
|
||
|
||
# Your command logic here
|
||
# ...
|
||
|
||
translation.deactivate()
|
||
|
||
Another need might be that your command simply should use the locale set in
|
||
settings and Django should be kept from forcing it to 'en-us'. You can achieve
|
||
it by using the :data:`BaseCommand.leave_locale_alone` option.
|
||
|
||
When working on the scenarios described above though, take into account that
|
||
system management commands typically have to be very careful about running in
|
||
non-uniform locales, so you might need to:
|
||
|
||
* Make sure the :setting:`USE_I18N` setting is always ``True`` when running
|
||
the command (this is a good example of the potential problems stemming
|
||
from a dynamic runtime environment that Django commands avoid offhand by
|
||
always using a fixed locale).
|
||
|
||
* Review the code of your command and the code it calls for behavioral
|
||
differences when locales are changed and evaluate its impact on
|
||
predictable behavior of your command.
|
||
|
||
Command objects
|
||
===============
|
||
|
||
.. class:: BaseCommand
|
||
|
||
The base class from which all management commands ultimately derive.
|
||
|
||
Use this class if you want access to all of the mechanisms which
|
||
parse the command-line arguments and work out what code to call in
|
||
response; if you don't need to change any of that behavior,
|
||
consider using one of its :ref:`subclasses<ref-basecommand-subclasses>`.
|
||
|
||
Subclassing the :class:`BaseCommand` class requires that you implement the
|
||
:meth:`~BaseCommand.handle` method.
|
||
|
||
Attributes
|
||
----------
|
||
|
||
All attributes can be set in your derived class and can be used in
|
||
:class:`BaseCommand`’s :ref:`subclasses<ref-basecommand-subclasses>`.
|
||
|
||
.. attribute:: BaseCommand.args
|
||
|
||
A string listing the arguments accepted by the command,
|
||
suitable for use in help messages; e.g., a command which takes
|
||
a list of application names might set this to '<app_label
|
||
app_label ...>'.
|
||
|
||
.. attribute:: BaseCommand.can_import_settings
|
||
|
||
A boolean indicating whether the command needs to be able to
|
||
import Django settings; if ``True``, ``execute()`` will verify
|
||
that this is possible before proceeding. Default value is
|
||
``True``.
|
||
|
||
.. attribute:: BaseCommand.help
|
||
|
||
A short description of the command, which will be printed in the
|
||
help message when the user runs the command
|
||
``python manage.py help <command>``.
|
||
|
||
.. attribute:: BaseCommand.option_list
|
||
|
||
This is the list of ``optparse`` options which will be fed
|
||
into the command's ``OptionParser`` for parsing arguments.
|
||
|
||
.. attribute:: BaseCommand.output_transaction
|
||
|
||
A boolean indicating whether the command outputs SQL
|
||
statements; if ``True``, the output will automatically be
|
||
wrapped with ``BEGIN;`` and ``COMMIT;``. Default value is
|
||
``False``.
|
||
|
||
.. attribute:: BaseCommand.requires_system_checks
|
||
|
||
.. versionadded:: 1.7
|
||
|
||
A boolean; if ``True``, the entire Django project will be checked for
|
||
potential problems prior to executing the command. If
|
||
``requires_system_checks`` is missing, the value of
|
||
``requires_model_validation`` is used. If the latter flag is missing
|
||
as well, the default value (``True``) is used. Defining both
|
||
``requires_system_checks`` and ``requires_model_validation`` will result
|
||
in an error.
|
||
|
||
.. attribute:: BaseCommand.requires_model_validation
|
||
|
||
.. deprecated:: 1.7
|
||
Replaced by ``requires_system_checks``
|
||
|
||
A boolean; if ``True``, validation of installed models will be
|
||
performed prior to executing the command. Default value is
|
||
``True``. To validate an individual application's models
|
||
rather than all applications' models, call
|
||
:meth:`~BaseCommand.validate` from :meth:`~BaseCommand.handle`.
|
||
|
||
.. attribute:: BaseCommand.leave_locale_alone
|
||
|
||
A boolean indicating whether the locale set in settings should be preserved
|
||
during the execution of the command instead of being forcibly set to 'en-us'.
|
||
|
||
Default value is ``False``.
|
||
|
||
Make sure you know what you are doing if you decide to change the value of
|
||
this option in your custom command if it creates database content that
|
||
is locale-sensitive and such content shouldn't contain any translations (like
|
||
it happens e.g. with django.contrib.auth permissions) as making the locale
|
||
differ from the de facto default 'en-us' might cause unintended effects. See
|
||
the `Management commands and locales`_ section above for further details.
|
||
|
||
This option can't be ``False`` when the
|
||
:data:`~BaseCommand.can_import_settings` option is set to ``False`` too
|
||
because attempting to set the locale needs access to settings. This condition
|
||
will generate a :class:`CommandError`.
|
||
|
||
.. versionadded:: 1.6
|
||
|
||
The ``leave_locale_alone`` option was added in Django 1.6.
|
||
|
||
Methods
|
||
-------
|
||
|
||
:class:`BaseCommand` has a few methods that can be overridden but only
|
||
the :meth:`~BaseCommand.handle` method must be implemented.
|
||
|
||
.. admonition:: Implementing a constructor in a subclass
|
||
|
||
If you implement ``__init__`` in your subclass of :class:`BaseCommand`,
|
||
you must call :class:`BaseCommand`’s ``__init__``.
|
||
|
||
.. code-block:: python
|
||
|
||
class Command(BaseCommand):
|
||
def __init__(self, *args, **kwargs):
|
||
super(Command, self).__init__(*args, **kwargs)
|
||
# ...
|
||
|
||
.. method:: BaseCommand.get_version()
|
||
|
||
Return the Django version, which should be correct for all
|
||
built-in Django commands. User-supplied commands can
|
||
override this method to return their own version.
|
||
|
||
.. method:: BaseCommand.execute(*args, **options)
|
||
|
||
Try to execute this command, performing model validation if
|
||
needed (as controlled by the attribute
|
||
:attr:`requires_model_validation`). If the command raises a
|
||
:class:`CommandError`, intercept it and print it sensibly to
|
||
stderr.
|
||
|
||
.. admonition:: Calling a management command in your code
|
||
|
||
``execute()`` should not be called directly from your code to execute a
|
||
command. Use :ref:`call_command <call-command>` instead.
|
||
|
||
.. method:: BaseCommand.handle(*args, **options)
|
||
|
||
The actual logic of the command. Subclasses must implement this method.
|
||
|
||
.. method:: BaseCommand.check(app_configs=None, tags=None, display_num_errors=False)
|
||
|
||
.. versionadded:: 1.7
|
||
|
||
Uses the system check framework to inspect the entire Django project for
|
||
potential problems. Serious problems are raised as a :class:`CommandError`;
|
||
warnings are output to stderr; minor notifications are output to stdout.
|
||
|
||
If ``app_configs`` and ``tags`` are both ``None``, all system checks are
|
||
performed. ``tags`` can be a list of check tags, like ``compatibility`` or
|
||
``models``.
|
||
|
||
.. method:: BaseCommand.validate(app=None, display_num_errors=False)
|
||
|
||
.. deprecated:: 1.7
|
||
Replaced with the :djadmin:`check` command
|
||
|
||
If ``app`` is None, then all installed apps are checked for errors.
|
||
|
||
.. _ref-basecommand-subclasses:
|
||
|
||
BaseCommand subclasses
|
||
----------------------
|
||
|
||
.. class:: AppCommand
|
||
|
||
A management command which takes one or more installed application labels as
|
||
arguments, and does something with each of them.
|
||
|
||
Rather than implementing :meth:`~BaseCommand.handle`, subclasses must
|
||
implement :meth:`~AppCommand.handle_app_config`, which will be called once for
|
||
each application.
|
||
|
||
.. method:: AppCommand.handle_app_config(app_config, **options)
|
||
|
||
Perform the command's actions for ``app_config``, which will be an
|
||
:class:`~django.apps.AppConfig` instance corresponding to an application
|
||
label given on the command line.
|
||
|
||
.. versionchanged:: 1.7
|
||
|
||
Previously, :class:`AppCommand` subclasses had to implement
|
||
``handle_app(app, **options)`` where ``app`` was a models module. The new
|
||
API makes it possible to handle applications without a models module. The
|
||
fastest way to migrate is as follows::
|
||
|
||
def handle_app_config(app_config, **options):
|
||
if app_config.models_module is None:
|
||
return # Or raise an exception.
|
||
app = app_config.models_module
|
||
# Copy the implementation of handle_app(app_config, **options) here.
|
||
|
||
However, you may be able to simplify the implementation by using directly
|
||
the attributes of ``app_config``.
|
||
|
||
.. class:: LabelCommand
|
||
|
||
A management command which takes one or more arbitrary arguments
|
||
(labels) on the command line, and does something with each of
|
||
them.
|
||
|
||
Rather than implementing :meth:`~BaseCommand.handle`, subclasses must implement
|
||
:meth:`~LabelCommand.handle_label`, which will be called once for each label.
|
||
|
||
.. method:: LabelCommand.handle_label(label, **options)
|
||
|
||
Perform the command's actions for ``label``, which will be the
|
||
string as given on the command line.
|
||
|
||
.. class:: NoArgsCommand
|
||
|
||
A command which takes no arguments on the command line.
|
||
|
||
Rather than implementing :meth:`~BaseCommand.handle`, subclasses must implement
|
||
:meth:`~NoArgsCommand.handle_noargs`; :meth:`~BaseCommand.handle` itself is
|
||
overridden to ensure no arguments are passed to the command.
|
||
|
||
.. method:: NoArgsCommand.handle_noargs(**options)
|
||
|
||
Perform this command's actions
|
||
|
||
.. _ref-command-exceptions:
|
||
|
||
Command exceptions
|
||
------------------
|
||
|
||
.. class:: CommandError
|
||
|
||
Exception class indicating a problem while executing a management
|
||
command.
|
||
|
||
If this exception is raised during the execution of a management
|
||
command from a command line console, it will be caught and turned into a
|
||
nicely-printed error message to the appropriate output stream (i.e., stderr);
|
||
as a result, raising this exception (with a sensible description of the
|
||
error) is the preferred way to indicate that something has gone
|
||
wrong in the execution of a command.
|
||
|
||
If a management command is called from code through
|
||
:ref:`call_command <call-command>`, it's up to you to catch the exception
|
||
when needed.
|