背景介绍
最近，尝试着用pythoncharm 这个All-star IDE来搞一搞Django，于是乎，下载专业版，PJ等等一系列操作之后，终于得偿所愿。可以开工了。
错误
在园子里找了一篇初学者的教程，按照教程上面的指导，一步一步往下走，一路上都很顺利。但是到了启动django server的时候出现了意外。
错误信息如下：
/home/ct/PycharmProjects/mysite/venv/bin/python /home/ct/PycharmProjects/mysite/manage.py runserver 127.0.0.1:
Traceback (most recent call last):
File "/home/ct/PycharmProjects/mysite/manage.py", line , in <module>
execute_from_command_line(sys.argv)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line , in execute_from_command_line
utility.execute()
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line , in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line , in run_from_argv
self.execute(*args, **cmd_options)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line , in execute
super(Command, self).execute(*args, **options)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line , in execute
output = self.handle(*args, **options)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line , in handle
if not settings.DEBUG and not settings.ALLOWED_HOSTS:
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/conf/__init__.py", line , in __getattr__
self._setup(name)
File "/home/ct/PycharmProjects/mysite/venv/local/lib/python2.7/site-packages/django/conf/__init__.py", line , in _setup
% (desc, ENVIRONMENT_VARIABLE)) django.core.exceptions.ImproperlyConfigured: Requested setting DEBUG, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.
Process finished with exit code
分析原因
最初，分析原因猜测是Django的安装出了问题； 但是，使用 terminal来启动django, 一切正常啊。
ct@ubuntu:~/PycharmProjects/mysite$ python manage.py runserver 127.0.0.1:
Performing system checks... System check identified no issues ( silenced). You have unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, sessions.
Run 'python manage.py migrate' to apply them. April , - ::
Django version 1.11, using settings 'mysite.settings' Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
思考了以后，感觉还是 pythoncharm 里，关于django的设置出了问题。于是打开IDE中的配置，发现缺失了 “DJANGO_SETTINGS_MODULE” 的配置
解决方法
顺着这个思路，一直找解决方案，终于找到了如何设置django项目的配置。
export DJANGO_SETTINGS_MODULE=mysite.settings
其实也就是添加环境变量罢了，只不过在pythoncharm中，我们需要将环境变量添加到IDE里面。。。
点击OK后，再次在pythoncharm里运行项目，这次成功啦！！
参考资料：
https://*.com/questions/26082128/improperlyconfigured-you-must-either-define-the-environment-variable-django-set
记录一下加深记忆的同时也希望能帮到其他人！！ 感谢大家的收看， bye~~