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 the subclasses defined in this file.
If you are interested in overriding/customizing various aspects of
the command-parsing and -execution behavior, the normal flow works
as follows:
1. ``django-admin`` or ``manage.py`` loads the command class
and calls its ``run_from_argv()`` method.
2. The ``run_from_argv()`` method calls ``create_parser()`` to get
an ``ArgumentParser`` for the arguments, parses them, performs
any environment changes requested by options like
``pythonpath``, and then calls the ``execute()`` method,
passing the parsed arguments.
3. The ``execute()`` method attempts to carry out the command by
calling the ``handle()`` method with the parsed arguments; any
output produced by ``handle()`` will be printed to standard
output and, if the command is intended to produce a block of
SQL statements, will be wrapped in ``BEGIN`` and ``COMMIT``.
4. If ``handle()`` or ``execute()`` raised any exception (e.g.
``CommandError``), ``run_from_argv()`` will instead print an error
message to ``stderr``.
Thus, the ``handle()`` method is typically the starting point for
subclasses; many built-in commands and command types either place
all of their logic in ``handle()``, or perform some additional
parsing work in ``handle()`` and then delegate from it to more
specialized methods as needed.
Several attributes affect behavior at various steps along the way:
``help``
A short description of the command, which will be printed in
help messages.
``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``.
``requires_migrations_checks``
A boolean; if ``True``, the command prints a warning if the set of
migrations on disk don't match the migrations in the database.
``requires_system_checks``
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 '__all__'.
To validate an individual application's models
rather than all applications' models, call
``self.check(app_configs)`` from ``handle()``, where ``app_configs``
is the list of application's configuration provided by the
app registry.
``stealth_options``
A tuple of any options the command uses which aren't defined by the
argument parser.This method is overriden in:
This method is overriden in:
Raise CommandError for any serious message (error or critical errors). If there are only light messages (like warnings), print them to stderr and don't raise an exception.
This method is overriden in:
This method is overriden in:
and Django settings), then run this command. If the command raises a ``CommandError``, intercept it and print it sensibly to stderr. If the ``--traceback`` option is present or the raised ``Exception`` is not ``CommandError``, raise it.
This method is overriden in: