周末无聊没事做又不想看电影了， 最近刚好学了一下python 并且用django 写了一个公司签到的打卡展示系统。想想就看看django源码好了。 不知道能坚持看多久。记录下

1. 先从github上fork一个。并把fork后的代码弄到本地工程里面。 现在最新的是1.9.4了。 我直接fork master

效果：

总目录下有个__main__.py 应该是比较重要的文件了。点进去

"""
Invokes django-admin when the django module is run as a script.Example: python -m django check"""
from django.core import managementif __name__ == "__main__":management.execute_from_command_line()

注释上写： 当django module 以脚本形式运行是调用django-admin  （好吧不太懂）

直接看看 execute_from_command_line 函数做了什么

def execute_from_command_line(argv=None):"""A simple method that runs a ManagementUtility."""utility = ManagementUtility(argv)utility.execute()

新建一个管理工具类。

类太多不贴了 贴个地址 ManagementUtility

到execute 方法里面

 def execute(self):"""Given the command-line arguments, this figures out which subcommand isbeing run, creates a parser appropriate to that command, and runs it."""try:subcommand = self.argv[1]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-alltry: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_APPSexcept 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.else:django.setup()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)

现在明白了注释里面的内容了

好现在我们可以测试一下：

直接运行__main__.py 这个文件。。 好出错了。 包没有导入。

难不倒我， 注释上不是说是django-admin 吗。 我打开bin 目录下的那个django-admin.py . 原来跟这个__main__.py 写的一样的。 运行一下试试。

Type 'django-admin.py help <subcommand>' for help on a specific subcommand.Available subcommands:[django]checkcompilemessagescreatecachetabledbshelldiffsettingsdumpdataflushinspectdbloaddatamakemessagesmakemigrationsmigraterunserversendtestemailshellshowmigrationssqlflushsqlmigratesqlsequenceresetsquashmigrationsstartappstartprojecttesttestserver
Note that only Django core commands are listed as settings are not properly configured (error: Requested setting INSTALLED_APPS, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.).

仔细阅读一下 里面可以输入很多参数。

试一下加个参数 management.execute_from_command_line(['','version']) 。 （这里稍微说明一下， 函数里面可以看到 它取的是第二个参数。第一个参数忽略了。 其实如果从命令行输入的话第一个参数是文件名）

也成功输入了 verison

今天就看到这。 其他的参数要配置一下环境了。