Source code for

Base classes for writing management commands (named commands which can
be executed through ``django-admin`` or ````).
import os
import sys
import warnings
from argparse import ArgumentParser, HelpFormatter
from io import TextIOBase

import django
from django.core import checks
from django.core.exceptions import ImproperlyConfigured
from import color_style, no_style
from django.db import DEFAULT_DB_ALIAS, connections
from django.utils.deprecation import RemovedInDjango41Warning

ALL_CHECKS = '__all__'

[docs]class CommandError(Exception): """ Exception class indicating a problem while executing a management command. If this exception is raised during the execution of a management command, 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. """ def __init__(self, *args, returncode=1, **kwargs): self.returncode = returncode super().__init__(*args, **kwargs)
class SystemCheckError(CommandError): """ The system check framework detected unrecoverable errors. """ pass class CommandParser(ArgumentParser): """ Customized ArgumentParser class to improve some error messages and prevent SystemExit in several occasions, as SystemExit is unacceptable when a command is called programmatically. """ def __init__(self, *, missing_args_message=None, called_from_command_line=None, **kwargs): self.missing_args_message = missing_args_message self.called_from_command_line = called_from_command_line super().__init__(**kwargs) def parse_args(self, args=None, namespace=None): # Catch missing argument for a better error message if (self.missing_args_message and not (args or any(not arg.startswith('-') for arg in args))): self.error(self.missing_args_message) return super().parse_args(args, namespace) def error(self, message): if self.called_from_command_line: super().error(message) else: raise CommandError("Error: %s" % message) def handle_default_options(options): """ Include any default options that all commands should accept here so that ManagementUtility can handle them before searching for user commands. """ if options.settings: os.environ['DJANGO_SETTINGS_MODULE'] = options.settings if options.pythonpath: sys.path.insert(0, options.pythonpath) def no_translations(handle_func): """Decorator that forces a command to run with translations deactivated.""" def wrapped(*args, **kwargs): from django.utils import translation saved_locale = translation.get_language() translation.deactivate_all() try: res = handle_func(*args, **kwargs) finally: if saved_locale is not None: translation.activate(saved_locale) return res return wrapped class DjangoHelpFormatter(HelpFormatter): """ Customized formatter so that command-specific arguments appear in the --help output before arguments common to all commands. """ show_last = { '--version', '--verbosity', '--traceback', '--settings', '--pythonpath', '--no-color', '--force-color', '--skip-checks', } def _reordered_actions(self, actions): return sorted( actions, key=lambda a: set(a.option_strings) & self.show_last != set() ) def add_usage(self, usage, actions, *args, **kwargs): super().add_usage(usage, self._reordered_actions(actions), *args, **kwargs) def add_arguments(self, actions): super().add_arguments(self._reordered_actions(actions)) class OutputWrapper(TextIOBase): """ Wrapper around stdout/stderr """ @property def style_func(self): return self._style_func @style_func.setter def style_func(self, style_func): if style_func and self.isatty(): self._style_func = style_func else: self._style_func = lambda x: x def __init__(self, out, ending='\n'): self._out = out self.style_func = None self.ending = ending def __getattr__(self, name): return getattr(self._out, name) def flush(self): if hasattr(self._out, 'flush'): self._out.flush() def isatty(self): return hasattr(self._out, 'isatty') and self._out.isatty() def write(self, msg='', style_func=None, ending=None): ending = self.ending if ending is None else ending if ending and not msg.endswith(ending): msg += ending style_func = style_func or self.style_func self._out.write(style_func(msg))
[docs]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 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 ```` 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. """ # Metadata about this command. help = '' # Configuration shortcuts that alter various logic. _called_from_command_line = False output_transaction = False # Whether to wrap the output in a "BEGIN; COMMIT;" requires_migrations_checks = False requires_system_checks = '__all__' # Arguments, common to all commands, which aren't defined by the argument # parser. base_stealth_options = ('stderr', 'stdout') # Command-specific options not defined by the argument parser. stealth_options = () def __init__(self, stdout=None, stderr=None, no_color=False, force_color=False): self.stdout = OutputWrapper(stdout or sys.stdout) self.stderr = OutputWrapper(stderr or sys.stderr) if no_color and force_color: raise CommandError("'no_color' and 'force_color' can't be used together.") if no_color: = no_style() else: = color_style(force_color) self.stderr.style_func = if self.requires_system_checks in [False, True]: warnings.warn( "Using a boolean value for requires_system_checks is " "deprecated. Use '__all__' instead of True, and [] (an empty " "list) instead of False.", RemovedInDjango41Warning, ) self.requires_system_checks = ALL_CHECKS if self.requires_system_checks else [] if ( not isinstance(self.requires_system_checks, (list, tuple)) and self.requires_system_checks != ALL_CHECKS ): raise TypeError('requires_system_checks must be a list or tuple.')
[docs] def get_version(self): """ 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. """ return django.get_version()
[docs] def create_parser(self, prog_name, subcommand, **kwargs): """ Create and return the ``ArgumentParser`` which will be used to parse the arguments to this command. """ parser = CommandParser( prog='%s %s' % (os.path.basename(prog_name), subcommand), or None, formatter_class=DjangoHelpFormatter, missing_args_message=getattr(self, 'missing_args_message', None), called_from_command_line=getattr(self, '_called_from_command_line', None), **kwargs ) parser.add_argument('--version', action='version', version=self.get_version()) parser.add_argument( '-v', '--verbosity', default=1, type=int, choices=[0, 1, 2, 3], help='Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output', ) parser.add_argument( '--settings', 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.' ), ) parser.add_argument( '--pythonpath', help='A directory to add to the Python path, e.g. "/home/djangoprojects/myproject".', ) parser.add_argument('--traceback', action='store_true', help='Raise on CommandError exceptions') parser.add_argument( '--no-color', action='store_true', help="Don't colorize the command output.", ) parser.add_argument( '--force-color', action='store_true', help='Force colorization of the command output.', ) if self.requires_system_checks: parser.add_argument( '--skip-checks', action='store_true', help='Skip system checks.', ) self.add_arguments(parser) return parser
[docs] def add_arguments(self, parser): """ Entry point for subclassed commands to add custom arguments. """ pass
def print_help(self, prog_name, subcommand): """ Print the help message for this command, derived from ``self.usage()``. """ parser = self.create_parser(prog_name, subcommand) parser.print_help() def run_from_argv(self, argv): """ Set up any environment changes requested (e.g., Python path 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. """ self._called_from_command_line = True parser = self.create_parser(argv[0], argv[1]) options = parser.parse_args(argv[2:]) cmd_options = vars(options) # Move positional args out of options to mimic legacy optparse args = cmd_options.pop('args', ()) handle_default_options(options) try: self.execute(*args, **cmd_options) except CommandError as e: if options.traceback: raise # SystemCheckError takes care of its own formatting. if isinstance(e, SystemCheckError): self.stderr.write(str(e), lambda x: x) else: self.stderr.write('%s: %s' % (e.__class__.__name__, e)) sys.exit(e.returncode) finally: try: connections.close_all() except ImproperlyConfigured: # Ignore if connections aren't setup at this point (e.g. no # configured settings). pass
[docs] def execute(self, *args, **options): """ Try to execute this command, performing system checks if needed (as controlled by the ``requires_system_checks`` attribute, except if force-skipped). """ if options['force_color'] and options['no_color']: raise CommandError("The --no-color and --force-color options can't be used together.") if options['force_color']: = color_style(force_color=True) elif options['no_color']: = no_style() self.stderr.style_func = None if options.get('stdout'): self.stdout = OutputWrapper(options['stdout']) if options.get('stderr'): self.stderr = OutputWrapper(options['stderr']) if self.requires_system_checks and not options['skip_checks']: if self.requires_system_checks == ALL_CHECKS: self.check() else: self.check(tags=self.requires_system_checks) if self.requires_migrations_checks: self.check_migrations() output = self.handle(*args, **options) if output: if self.output_transaction: connection = connections[options.get('database', DEFAULT_DB_ALIAS)] output = '%s\n%s\n%s' % (, output,, ) self.stdout.write(output) return output
[docs] def check(self, app_configs=None, tags=None, display_num_errors=False, include_deployment_checks=False, fail_level=checks.ERROR, databases=None): """ Use the system check framework to validate entire Django project. 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. """ all_issues = checks.run_checks( app_configs=app_configs, tags=tags, include_deployment_checks=include_deployment_checks, databases=databases, ) header, body, footer = "", "", "" visible_issue_count = 0 # excludes silenced warnings if all_issues: debugs = [e for e in all_issues if e.level < checks.INFO and not e.is_silenced()] infos = [e for e in all_issues if checks.INFO <= e.level < checks.WARNING and not e.is_silenced()] warnings = [e for e in all_issues if checks.WARNING <= e.level < checks.ERROR and not e.is_silenced()] errors = [e for e in all_issues if checks.ERROR <= e.level < checks.CRITICAL and not e.is_silenced()] criticals = [e for e in all_issues if checks.CRITICAL <= e.level and not e.is_silenced()] sorted_issues = [ (criticals, 'CRITICALS'), (errors, 'ERRORS'), (warnings, 'WARNINGS'), (infos, 'INFOS'), (debugs, 'DEBUGS'), ] for issues, group_name in sorted_issues: if issues: visible_issue_count += len(issues) formatted = ( if e.is_serious() else for e in issues) formatted = "\n".join(sorted(formatted)) body += '\n%s:\n%s\n' % (group_name, formatted) if visible_issue_count: header = "System check identified some issues:\n" if display_num_errors: if visible_issue_count: footer += '\n' footer += "System check identified %s (%s silenced)." % ( "no issues" if visible_issue_count == 0 else "1 issue" if visible_issue_count == 1 else "%s issues" % visible_issue_count, len(all_issues) - visible_issue_count, ) if any(e.is_serious(fail_level) and not e.is_silenced() for e in all_issues): msg ="SystemCheckError: %s" % header) + body + footer raise SystemCheckError(msg) else: msg = header + body + footer if msg: if visible_issue_count: self.stderr.write(msg, lambda x: x) else: self.stdout.write(msg)
def check_migrations(self): """ Print a warning if the set of migrations on disk don't match the migrations in the database. """ from django.db.migrations.executor import MigrationExecutor try: executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS]) except ImproperlyConfigured: # No databases are configured (or the dummy one) return plan = executor.migration_plan(executor.loader.graph.leaf_nodes()) if plan: apps_waiting_migration = sorted({migration.app_label for migration, backwards in plan}) self.stdout.write( "\nYou have %(unapplied_migration_count)s unapplied migration(s). " "Your project may not work properly until you apply the " "migrations for app(s): %(apps_waiting_migration)s." % { "unapplied_migration_count": len(plan), "apps_waiting_migration": ", ".join(apps_waiting_migration), } ) ) self.stdout.write("Run 'python migrate' to apply them."))
[docs] def handle(self, *args, **options): """ The actual logic of the command. Subclasses must implement this method. """ raise NotImplementedError('subclasses of BaseCommand must provide a handle() method')
class AppCommand(BaseCommand): """ 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 implement ``handle_app_config()``, which will be called once for each application. """ missing_args_message = "Enter at least one application label." def add_arguments(self, parser): parser.add_argument('args', metavar='app_label', nargs='+', help='One or more application label.') def handle(self, *app_labels, **options): from django.apps import apps try: app_configs = [apps.get_app_config(app_label) for app_label in app_labels] except (LookupError, ImportError) as e: raise CommandError("%s. Are you sure your INSTALLED_APPS setting is correct?" % e) output = [] for app_config in app_configs: app_output = self.handle_app_config(app_config, **options) if app_output: output.append(app_output) return '\n'.join(output) def handle_app_config(self, app_config, **options): """ Perform the command's actions for app_config, an AppConfig instance corresponding to an application label given on the command line. """ raise NotImplementedError( "Subclasses of AppCommand must provide" "a handle_app_config() method.") class LabelCommand(BaseCommand): """ 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. If the arguments should be names of installed applications, use ``AppCommand`` instead. """ label = 'label' missing_args_message = "Enter at least one %s." % label def add_arguments(self, parser): parser.add_argument('args', metavar=self.label, nargs='+') def handle(self, *labels, **options): output = [] for label in labels: label_output = self.handle_label(label, **options) if label_output: output.append(label_output) return '\n'.join(output) def handle_label(self, label, **options): """ Perform the command's actions for ``label``, which will be the string as given on the command line. """ raise NotImplementedError('subclasses of LabelCommand must provide a handle_label() method')
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