django 源码阅读二 命令check

摘要: 查看django-admin check 命令

接着昨天的看 源码阅读一

上次看的django-admin 命令下只能执行help 跟一个version。 这次看看check 命令执行流程

要运行要先配置 一个setting。 你可以用已有项目里面的配置文件

我直接复制一个配置文件到 django-admin.py 的这个文件下面，并且删掉一些东西

"""
Django settings for Attendance_system project.

Generated by 'django-admin startproject' using Django 1.9.1.

For more information on this file, see https://docs.djangoproject.com/en/1.9/topics/settings/ 
For the full list of settings and their values, see https://docs.djangoproject.com/en/1.9/ref/settings/ """

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '3$j)!r#3v_$s96277jyd)hv!2irwzgvkyr8g6c0g6b#cuwt@0='

只剩一个 SECRET_KEY 配置。

并且在运行文件加上一行 os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")

结构变成这样了



先运行一下结果是：System check identified no issues (0 silenced).

搞个断点调试看代码。

def execute(self):
"""
Given the command-line arguments, this figures out which subcommand is
being run, creates a parser appropriate to that command, and runs it.
"""
try:
subcommand = self.argv[1]   # 如果没有传参数就默认输出help
except IndexError:
subcommand = 'help'  # Display help if no arguments were given.

# Preprocess options to extract --settings and --pythonpath.
# These options could affect the commands that are available, so they
# must be processed early.
parser = CommandParser(None, usage="%(prog)s subcommand [options] [args]", add_help=False)
parser.add_argument('--settings')
parser.add_argument('--pythonpath')
parser.add_argument('args', nargs='*')  # catch-all
try:
options, args = parser.parse_known_args(self.argv[2:])
handle_default_options(options)
except CommandError:
pass  # Ignore any option errors at this point.

no_settings_commands = [
'help', 'version', '--help', '--version', '-h',
'compilemessages', 'makemessages',
'startapp', 'startproject',
]

try:
settings.INSTALLED_APPS
except ImproperlyConfigured as exc:
self.settings_exception = exc
# A handful of built-in management commands work without settings.
# Load the default settings -- where INSTALLED_APPS is empty.
if subcommand in no_settings_commands:
settings.configure()

if settings.configured:
# Start the auto-reloading dev server even if the code is broken.
# The hardcoded condition is a code smell but we can't rely on a
# flag on the command class because we haven't located it yet.
if subcommand == 'runserver' and '--noreload' not in self.argv:
try:
autoreload.check_errors(django.setup)()
except Exception:
# The exception will be raised later in the child process
# started by the autoreloader. Pretend it didn't happen by
# loading an empty list of applications.
apps.all_models = defaultdict(OrderedDict)
apps.app_configs = OrderedDict()
apps.apps_ready = apps.models_ready = apps.ready = True

# In all other cases, django.setup() is required to succeed. 注意这个注释。
else:
django.setup()  # check 命令要求这个必须要运行成功。主要做检查 加载 判断模块是否重名等等。                                # 有兴趣可以跳进去看看

self.autocomplete()

if subcommand == 'help':
if '--commands' in args:
sys.stdout.write(self.main_help_text(commands_only=True) + '\n')
elif len(options.args) < 1:
sys.stdout.write(self.main_help_text() + '\n')
else:
self.fetch_command(options.args[0]).print_help(self.prog_name, options.args[0])
# Special-cases: We want 'django-admin --version' and
# 'django-admin --help' to work, for backwards compatibility.
elif subcommand == 'version' or self.argv[1:] == ['--version']:
sys.stdout.write(django.get_version() + '\n')
elif self.argv[1:] in (['--help'], ['-h']):
sys.stdout.write(self.main_help_text() + '\n')
else:
self.fetch_command(subcommand).run_from_argv(self.argv)  # 程序运行进入这里
# 调用management->commands->check.py 这个文件。 然后就进行了各种check。