""" Base classes for writing management commands (named commands which can be executed through ``django-admin.py`` or ``manage.py``). """ import os import sys from optparse import make_option, OptionParser import django from django.core.exceptions import ImproperlyConfigured from django.core.management.color import color_style from django.utils.encoding import smart_str 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. """ pass 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) class BaseCommand(object): """ 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.py`` 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 ``OptionParser`` 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()`` raised a ``CommandError``, ``execute()`` 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: ``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 ''. ``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``. ``help`` A short description of the command, which will be printed in help messages. ``option_list`` This is the list of ``optparse`` options which will be fed into the command's ``OptionParser`` for parsing arguments. ``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_model_validation`` 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 ``self.validate(app)`` from ``handle()``, where ``app`` is the application's Python module. """ # Metadata about this command. option_list = ( make_option('-v', '--verbosity', action='store', dest='verbosity', default='1', type='choice', choices=['0', '1', '2'], help='Verbosity level; 0=minimal output, 1=normal output, 2=all output'), make_option('--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.'), make_option('--pythonpath', help='A directory to add to the Python path, e.g. "/home/djangoprojects/myproject".'), make_option('--traceback', action='store_true', help='Print traceback on exception'), ) help = '' args = '' # Configuration shortcuts that alter various logic. can_import_settings = True requires_model_validation = True output_transaction = False # Whether to wrap the output in a "BEGIN; COMMIT;" def __init__(self): self.style = color_style() def get_version(self): """ Return the Django version, which should be correct for all built-in Django commands. User-supplied commands should override this method. """ return django.get_version() def usage(self, subcommand): """ Return a brief description of how to use this command, by default from the attribute ``self.help``. """ usage = '%%prog %s [options] %s' % (subcommand, self.args) if self.help: return '%s\n\n%s' % (usage, self.help) else: return usage def create_parser(self, prog_name, subcommand): """ Create and return the ``OptionParser`` which will be used to parse the arguments to this command. """ return OptionParser(prog=prog_name, usage=self.usage(subcommand), version=self.get_version(), option_list=self.option_list) 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. """ parser = self.create_parser(argv[0], argv[1]) options, args = parser.parse_args(argv[2:]) handle_default_options(options) self.execute(*args, **options.__dict__) def execute(self, *args, **options): """ Try to execute this command, performing model validation if needed (as controlled by the attribute ``self.requires_model_validation``). If the command raises a ``CommandError``, intercept it and print it sensibly to stderr. """ # Switch to English, because django-admin.py creates database content # like permissions, and those shouldn't contain any translations. # But only do this if we can assume we have a working settings file, # because django.utils.translation requires settings. if self.can_import_settings: try: from django.utils import translation translation.activate('en-us') except ImportError, e: # If settings should be available, but aren't, # raise the error and quit. sys.stderr.write(smart_str(self.style.ERROR('Error: %s\n' % e))) sys.exit(1) try: if self.requires_model_validation: self.validate() output = self.handle(*args, **options) if output: if self.output_transaction: # This needs to be imported here, because it relies on settings. from django.db import connection if connection.ops.start_transaction_sql(): print self.style.SQL_KEYWORD(connection.ops.start_transaction_sql()) print output if self.output_transaction: print self.style.SQL_KEYWORD("COMMIT;") except CommandError, e: sys.stderr.write(smart_str(self.style.ERROR('Error: %s\n' % e))) sys.exit(1) def validate(self, app=None, display_num_errors=False): """ Validates the given app, raising CommandError for any errors. If app is None, then this will validate all installed apps. """ from django.core.management.validation import get_validation_errors try: from cStringIO import StringIO except ImportError: from StringIO import StringIO s = StringIO() num_errors = get_validation_errors(s, app) if num_errors: s.seek(0) error_text = s.read() raise CommandError("One or more models did not validate:\n%s" % error_text) if display_num_errors: print "%s error%s found" % (num_errors, num_errors != 1 and 's' or '') def handle(self, *args, **options): """ The actual logic of the command. Subclasses must implement this method. """ raise NotImplementedError() class AppCommand(BaseCommand): """ A management command which takes one or more installed application names as arguments, and does something with each of them. Rather than implementing ``handle()``, subclasses must implement ``handle_app()``, which will be called once for each application. """ args = '' def handle(self, *app_labels, **options): from django.db import models if not app_labels: raise CommandError('Enter at least one appname.') try: app_list = [models.get_app(app_label) for app_label in app_labels] except (ImproperlyConfigured, ImportError), e: raise CommandError("%s. Are you sure your INSTALLED_APPS setting is correct?" % e) output = [] for app in app_list: app_output = self.handle_app(app, **options) if app_output: output.append(app_output) return '\n'.join(output) def handle_app(self, app, **options): """ Perform the command's actions for ``app``, which will be the Python module corresponding to an application name given on the command line. """ raise NotImplementedError() 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. """ args = '