379 lines
13 KiB
Python
379 lines
13 KiB
Python
"""
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Base classes for writing management commands (named commands which can
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be executed through ``django-admin.py`` or ``manage.py``).
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"""
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import os
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import sys
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from optparse import make_option, OptionParser
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import traceback
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import django
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from django.core.exceptions import ImproperlyConfigured
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from django.core.management.color import color_style
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from django.utils.encoding import smart_str
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class CommandError(Exception):
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"""
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Exception class indicating a problem while executing a management
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command.
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If this exception is raised during the execution of a management
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command, it will be caught and turned into a nicely-printed error
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message to the appropriate output stream (i.e., stderr); as a
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result, raising this exception (with a sensible description of the
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error) is the preferred way to indicate that something has gone
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wrong in the execution of a command.
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"""
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pass
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def handle_default_options(options):
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"""
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Include any default options that all commands should accept here
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so that ManagementUtility can handle them before searching for
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user commands.
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"""
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if options.settings:
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os.environ['DJANGO_SETTINGS_MODULE'] = options.settings
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if options.pythonpath:
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sys.path.insert(0, options.pythonpath)
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class BaseCommand(object):
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"""
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The base class from which all management commands ultimately
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derive.
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Use this class if you want access to all of the mechanisms which
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parse the command-line arguments and work out what code to call in
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response; if you don't need to change any of that behavior,
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consider using one of the subclasses defined in this file.
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If you are interested in overriding/customizing various aspects of
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the command-parsing and -execution behavior, the normal flow works
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as follows:
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1. ``django-admin.py`` or ``manage.py`` loads the command class
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and calls its ``run_from_argv()`` method.
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2. The ``run_from_argv()`` method calls ``create_parser()`` to get
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an ``OptionParser`` for the arguments, parses them, performs
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any environment changes requested by options like
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``pythonpath``, and then calls the ``execute()`` method,
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passing the parsed arguments.
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3. The ``execute()`` method attempts to carry out the command by
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calling the ``handle()`` method with the parsed arguments; any
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output produced by ``handle()`` will be printed to standard
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output and, if the command is intended to produce a block of
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SQL statements, will be wrapped in ``BEGIN`` and ``COMMIT``.
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4. If ``handle()`` raised a ``CommandError``, ``execute()`` will
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instead print an error message to ``stderr``.
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Thus, the ``handle()`` method is typically the starting point for
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subclasses; many built-in commands and command types either place
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all of their logic in ``handle()``, or perform some additional
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parsing work in ``handle()`` and then delegate from it to more
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specialized methods as needed.
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Several attributes affect behavior at various steps along the way:
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``args``
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A string listing the arguments accepted by the command,
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suitable for use in help messages; e.g., a command which takes
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a list of application names might set this to '<appname
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appname ...>'.
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``can_import_settings``
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A boolean indicating whether the command needs to be able to
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import Django settings; if ``True``, ``execute()`` will verify
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that this is possible before proceeding. Default value is
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``True``.
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``help``
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A short description of the command, which will be printed in
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help messages.
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``option_list``
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This is the list of ``optparse`` options which will be fed
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into the command's ``OptionParser`` for parsing arguments.
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``output_transaction``
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A boolean indicating whether the command outputs SQL
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statements; if ``True``, the output will automatically be
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wrapped with ``BEGIN;`` and ``COMMIT;``. Default value is
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``False``.
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``requires_model_validation``
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A boolean; if ``True``, validation of installed models will be
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performed prior to executing the command. Default value is
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``True``. To validate an individual application's models
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rather than all applications' models, call
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``self.validate(app)`` from ``handle()``, where ``app`` is the
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application's Python module.
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"""
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# Metadata about this command.
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option_list = (
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make_option('-v', '--verbosity', action='store', dest='verbosity', default='1',
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type='choice', choices=['0', '1', '2', '3'],
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help='Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output'),
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make_option('--settings',
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help='The Python path to a settings module, e.g. "myproject.settings.main". If this isn\'t provided, the DJANGO_SETTINGS_MODULE environment variable will be used.'),
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make_option('--pythonpath',
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help='A directory to add to the Python path, e.g. "/home/djangoprojects/myproject".'),
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make_option('--traceback', action='store_true',
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help='Print traceback on exception'),
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)
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help = ''
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args = ''
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# Configuration shortcuts that alter various logic.
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can_import_settings = True
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requires_model_validation = True
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output_transaction = False # Whether to wrap the output in a "BEGIN; COMMIT;"
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def __init__(self):
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self.style = color_style()
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def get_version(self):
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"""
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Return the Django version, which should be correct for all
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built-in Django commands. User-supplied commands should
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override this method.
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"""
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return django.get_version()
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def usage(self, subcommand):
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"""
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Return a brief description of how to use this command, by
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default from the attribute ``self.help``.
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"""
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usage = '%%prog %s [options] %s' % (subcommand, self.args)
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if self.help:
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return '%s\n\n%s' % (usage, self.help)
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else:
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return usage
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def create_parser(self, prog_name, subcommand):
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"""
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Create and return the ``OptionParser`` which will be used to
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parse the arguments to this command.
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"""
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return OptionParser(prog=prog_name,
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usage=self.usage(subcommand),
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version=self.get_version(),
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option_list=self.option_list)
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def print_help(self, prog_name, subcommand):
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"""
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Print the help message for this command, derived from
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``self.usage()``.
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"""
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parser = self.create_parser(prog_name, subcommand)
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parser.print_help()
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def run_from_argv(self, argv):
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"""
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Set up any environment changes requested (e.g., Python path
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and Django settings), then run this command.
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"""
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parser = self.create_parser(argv[0], argv[1])
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options, args = parser.parse_args(argv[2:])
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handle_default_options(options)
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self.execute(*args, **options.__dict__)
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def execute(self, *args, **options):
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"""
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Try to execute this command, performing model validation if
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needed (as controlled by the attribute
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``self.requires_model_validation``). If the command raises a
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``CommandError``, intercept it and print it sensibly to
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stderr.
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"""
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show_traceback = options.get('traceback', False)
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# Switch to English, because django-admin.py creates database content
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# like permissions, and those shouldn't contain any translations.
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# But only do this if we can assume we have a working settings file,
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# because django.utils.translation requires settings.
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saved_lang = None
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if self.can_import_settings:
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try:
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from django.utils import translation
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saved_lang = translation.get_language()
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translation.activate('en-us')
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except ImportError, e:
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# If settings should be available, but aren't,
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# raise the error and quit.
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if show_traceback:
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traceback.print_exc()
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else:
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sys.stderr.write(smart_str(self.style.ERROR('Error: %s\n' % e)))
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sys.exit(1)
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try:
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self.stdout = options.get('stdout', sys.stdout)
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self.stderr = options.get('stderr', sys.stderr)
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if self.requires_model_validation:
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self.validate()
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output = self.handle(*args, **options)
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if output:
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if self.output_transaction:
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# This needs to be imported here, because it relies on
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# settings.
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from django.db import connections, DEFAULT_DB_ALIAS
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connection = connections[options.get('database', DEFAULT_DB_ALIAS)]
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if connection.ops.start_transaction_sql():
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self.stdout.write(self.style.SQL_KEYWORD(connection.ops.start_transaction_sql()) + '\n')
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self.stdout.write(output)
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if self.output_transaction:
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self.stdout.write('\n' + self.style.SQL_KEYWORD("COMMIT;") + '\n')
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except CommandError, e:
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if show_traceback:
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traceback.print_exc()
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else:
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self.stderr.write(smart_str(self.style.ERROR('Error: %s\n' % e)))
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sys.exit(1)
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finally:
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if saved_lang is not None:
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translation.activate(saved_lang)
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def validate(self, app=None, display_num_errors=False):
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"""
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Validates the given app, raising CommandError for any errors.
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If app is None, then this will validate all installed apps.
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"""
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from django.core.management.validation import get_validation_errors
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try:
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from cStringIO import StringIO
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except ImportError:
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from StringIO import StringIO
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s = StringIO()
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num_errors = get_validation_errors(s, app)
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if num_errors:
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s.seek(0)
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error_text = s.read()
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raise CommandError("One or more models did not validate:\n%s" % error_text)
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if display_num_errors:
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self.stdout.write("%s error%s found\n" % (num_errors, num_errors != 1 and 's' or ''))
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def handle(self, *args, **options):
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"""
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The actual logic of the command. Subclasses must implement
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this method.
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"""
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raise NotImplementedError()
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class AppCommand(BaseCommand):
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"""
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A management command which takes one or more installed application
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names as arguments, and does something with each of them.
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Rather than implementing ``handle()``, subclasses must implement
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``handle_app()``, which will be called once for each application.
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"""
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args = '<appname appname ...>'
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def handle(self, *app_labels, **options):
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from django.db import models
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if not app_labels:
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raise CommandError('Enter at least one appname.')
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try:
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app_list = [models.get_app(app_label) for app_label in app_labels]
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except (ImproperlyConfigured, ImportError), e:
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raise CommandError("%s. Are you sure your INSTALLED_APPS setting is correct?" % e)
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output = []
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for app in app_list:
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app_output = self.handle_app(app, **options)
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if app_output:
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output.append(app_output)
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return '\n'.join(output)
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def handle_app(self, app, **options):
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"""
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Perform the command's actions for ``app``, which will be the
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Python module corresponding to an application name given on
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the command line.
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"""
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raise NotImplementedError()
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class LabelCommand(BaseCommand):
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"""
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A management command which takes one or more arbitrary arguments
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(labels) on the command line, and does something with each of
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them.
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Rather than implementing ``handle()``, subclasses must implement
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``handle_label()``, which will be called once for each label.
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If the arguments should be names of installed applications, use
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``AppCommand`` instead.
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"""
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args = '<label label ...>'
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label = 'label'
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def handle(self, *labels, **options):
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if not labels:
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raise CommandError('Enter at least one %s.' % self.label)
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output = []
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for label in labels:
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label_output = self.handle_label(label, **options)
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if label_output:
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output.append(label_output)
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return '\n'.join(output)
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def handle_label(self, label, **options):
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"""
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Perform the command's actions for ``label``, which will be the
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string as given on the command line.
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"""
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raise NotImplementedError()
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class NoArgsCommand(BaseCommand):
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"""
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A command which takes no arguments on the command line.
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Rather than implementing ``handle()``, subclasses must implement
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``handle_noargs()``; ``handle()`` itself is overridden to ensure
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no arguments are passed to the command.
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Attempting to pass arguments will raise ``CommandError``.
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"""
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args = ''
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def handle(self, *args, **options):
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if args:
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raise CommandError("Command doesn't accept any arguments")
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return self.handle_noargs(**options)
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def handle_noargs(self, **options):
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"""
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Perform this command's actions.
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"""
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raise NotImplementedError()
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