- Language: en
How to create custom
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
command for the
polls application from the
To do this, 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
_private.py module will not be available as a management command.
closepoll.py module has only one requirement – it must define a class
Command that extends
BaseCommand or one of its
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
look like this:
from django.core.management.base import BaseCommand, CommandError from polls.models import Question as Poll class Command(BaseCommand): help = "Closes the specified poll for voting" def add_arguments(self, parser): parser.add_argument("poll_ids", nargs="+", type=int) def handle(self, *args, **options): for poll_id in options["poll_ids"]: try: poll = Poll.objects.get(pk=poll_id) except Poll.DoesNotExist: raise CommandError('Poll "%s" does not exist' % poll_id) poll.opened = False poll.save() self.stdout.write( self.style.SUCCESS('Successfully closed poll "%s"' % poll_id) )
When you are using management commands and wish to provide console
output, you should write to
instead of printing to
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
self.stdout.write("Unterminated line", ending="")
The new custom command can be called using
python manage.py closepoll
handle() method takes one or more
poll_ids and sets
False for each one. If the user referenced any nonexistent polls, a
CommandError is raised. The
poll.opened attribute does not exist in
the tutorial and was added to
polls.models.Question for this example.
Accepting optional arguments¶
closepoll could be easily modified to delete a given poll instead
of closing it by accepting additional command line options. These custom
options can be added in the
add_arguments() method like this:
class Command(BaseCommand): def add_arguments(self, parser): # Positional arguments parser.add_argument("poll_ids", nargs="+", type=int) # Named (optional) arguments parser.add_argument( "--delete", action="store_true", 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
argparse Python documentation
for more about
In addition to being able to add custom command line options, all
management commands can accept some default options
Management commands and locales¶
By default, management commands are executed with the current active locale.
If, for some reason, your custom management command must run without an active
locale (for example, to prevent translated content from being inserted into
the database), deactivate translations using the
decorator on your
from django.core.management.base import BaseCommand, no_translations class Command(BaseCommand): ... @no_translations def handle(self, *args, **options): ...
Since translation deactivation requires access to configured settings, the decorator can’t be used for commands that work without configured settings.
Information on how to test custom management commands can be found in the testing docs.
Django registers the built-in commands and then searches for commands in
INSTALLED_APPS in reverse. During the search, if a command name
duplicates an already registered command, the newly discovered command
overrides the first.
In other words, to override a command, the new command must have the same name
and its app must be before the overridden command’s app in
Management commands from third-party apps that have been unintentionally
overridden can be made available under a new name by creating a new command in
one of your project’s apps (ordered before the third-party app in
INSTALLED_APPS) which imports the
Command of the overridden
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 subclasses.
BaseCommand class requires that you implement the
All attributes can be set in your derived class and can be used in
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>.
If your command defines mandatory positional arguments, you can customize the message error returned in the case of missing arguments. The default is output by
argparse(“too few arguments”).
A boolean indicating whether the command outputs SQL statements; if
True, the output will automatically be wrapped with
COMMIT;. Default value is
A boolean; if
True, the command prints a warning if the set of migrations on disk don’t match the migrations in the database. A warning doesn’t prevent the command from executing. Default value is
A list or tuple of tags, e.g.
[Tags.staticfiles, Tags.models]. System checks registered in the chosen tags will be checked for errors prior to executing the command. The value
'__all__'can be used to specify that all system checks should be performed. Default value is
An instance attribute that helps create colored output when writing to
stderr. For example:
See Syntax coloring to learn how to modify the color palette and to see the available styles (use uppercased versions of the “roles” described in that section).
If you pass the
--no-coloroption when running your command, all
self.style()calls will return the original string uncolored.
The default command options to suppress in the help output. This should be a set of option names (e.g.
'--verbosity'). The default values for the suppressed options are still passed.
BaseCommand has a few methods that can be overridden but only
handle() method must be implemented.
Implementing a constructor in a subclass
If you implement
__init__ in your subclass of
you must call
class Command(BaseCommand): def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) # ...
create_parser(prog_name, subcommand, **kwargs)¶
CommandParserinstance, which is an
ArgumentParsersubclass with a few customizations for Django.
You can customize the instance by overriding this method and calling
Entry point to add parser arguments to handle command line arguments passed to the command. Custom commands should override this method to add both positional and optional arguments accepted by the command. Calling
super()is not needed when directly subclassing
Returns 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.
Tries to execute this command, performing system checks if needed (as controlled by the
requires_system_checksattribute). If the command raises a
CommandError, it’s intercepted and printed to
Calling a management command in your code
execute() should not be called directly from your code to execute a
The actual logic of the command. Subclasses must implement this method.
It may return a string which will be printed to
check(app_configs=None, tags=None, display_num_errors=False)¶
Uses the system check framework to inspect the entire Django project for potential problems. Serious problems are raised as a
CommandError; warnings are output to
stderr; minor notifications are output to
None, all system checks are performed.
tagscan be a list of check tags, like
A management command which takes one or more installed application labels as arguments, and does something with each of them.
Rather than implementing
handle(), subclasses must
handle_app_config(), which will be called once for
Perform the command’s actions for
app_config, which will be an
AppConfiginstance corresponding to an application label given on the command line.
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
handle(), subclasses must implement
handle_label(), which will be called once for each label.
A string describing the arbitrary arguments passed to the command. The string is used in the usage text and error messages of the command. Defaults to
Perform the command’s actions for
label, which will be the string as given on the command line.
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. It accepts the optional
returncode argument to customize the exit
status for the management command to exit with, using
If a management command is called from code through
call_command(), it’s up to you to catch the
exception when needed.