关于django python manage.py startapp 应用名出错异常原因解析

关于django项目中使用python manage.py startapp 应用名命令出现异常的问题，一般有以下两种情况：

1. 应用名命名不规范

在创建应用时，如果应用名不规范，将会出现异常。在django中，应用名需要遵循以下规则：

• 应用名只能包含字母、数字和下划线；
• 应用名不能以数字开头；
• 应用名不能与已有的django关键字重名，例如：admin, auth, contenttypes 等。

示例：

当我尝试运行以下命令时：python manage.py startapp test-1。将会看到以下类似的异常信息：

Traceback (most recent call last):
      File "manage.py", line 22, in <module>
        main()
      File "manage.py", line 18, in main
        execute_from_command_line(sys.argv)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
        utility.execute()
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
        self.execute(*args, **cmd_options)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute
        output = self.handle(*args, **options)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 141, in handle
        self.check()
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 371, in check
        include_deployment_checks=include_deployment_checks,
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/commands/check.py", line 59, in _run_checks
        return checks.run_checks(**kwargs)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/checks/registry.py", line 76, in run_checks
        new_errors = check(app_configs=app_configs)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/checks/urls.py", line 13, in check_url_config
        return check_resolver(resolver)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/checks/urls.py", line 23, in check_resolver
        return check_method()
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/urls/resolvers.py", line 398, in check
        for pattern in self.url_patterns:
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/utils/functional.py", line 80, in __get__
        res = instance.__dict__[self.name] = self.func(instance)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/urls/resolvers.py", line 579, in url_patterns
        patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/utils/functional.py", line 80, in __get__
        res = instance.__dict__[self.name] = self.func(instance)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/urls/resolvers.py", line 572, in urlconf_module
        return import_module(self.urlconf_name)
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/importlib/__init__.py", line 126, in import_module
        return _bootstrap._gcd_import(name[level:], package, level)
      File "<frozen importlib._bootstrap>", line 994, in _gcd_import
      File "<frozen importlib._bootstrap>", line 971, in _find_and_load
      File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
      File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
      File "<frozen importlib._bootstrap_external>", line 678, in exec_module
      File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
      File "/Users/xxx/test_project/test_project/urls.py", line 22, in <module>
        url(r'^', include('test-1.urls')),
    ValueError: invalid literal for int() with base 10: '1/'

其中包含ValueError的异常信息，这是因为应用名中含有-，导致django无法正确地解析应用名，而产生的一个错误。

2. Django项目配置异常

此种异常通常指的是当我们尝试在一个没有初始化为django项目的文件夹中新建一个django项目，并在项目中尝试使用python manage.py startapp 应用名命令时，会出现异常。这是因为django项目的配置在创建项目时就需要初始化。

示例：

当我尝试在一个无法解析为django项目的文件夹中运行以下命令时：python manage.py startapp test。将会看到以下类似的异常信息：

Traceback (most recent call last):
      File "manage.py", line 10, in <module>
        execute_from_command_line(sys.argv)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
        utility.execute()
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
        self.execute(*args, **cmd_options)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute
        output = self.handle(*args, **options)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 141, in handle
        self.check()
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/base.py", line 371, in check
        include_deployment_checks=include_deployment_checks,
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/management/commands/check.py", line 59, in _run_checks
        return checks.run_checks(**kwargs)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/checks/registry.py", line 76, in run_checks
        new_errors = check(app_configs=app_configs)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/core/checks/databases.py", line 10, in check_database_backends
        for conn in connections.all():
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/db/utils.py", line 212, in all
        return [self[alias] for alias in self]
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/db/utils.py", line 212, in <listcomp>
        return [self[alias] for alias in self]
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/db/utils.py", line 187, in __getitem__
        conn = backend.DatabaseWrapper(db, alias)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/db/backends/__init__.py", line 181, in __init__
        self.ops = ConnectionOps(self)
      File "/Users/xxx/.virtualenvs/test/lib/python3.6/site-packages/django/db/backends/mysql/operations.py", line 86, in __init__
        super().__init__()
    TypeError: super() takes at least 1 argument (0 given)

其中包含了TypeError的异常信息，这是因为我们尝试在一个没有初始化为django项目的文件夹中尝试新建一个django应用，而产生的一个错误。