[python] can not find app ,module

• can not find module

　　　1 startapp appname 而不是 startproject

　　　2 不要自己创建项目根目录，要用mamage.py生成

• can not find app:　

　　因为copy code而误删modell里的：from __future__ import unicode_literals

• doesn't declare an explicit app_label

Traceback (most recent call last):
  File "<input>", line , in <module>
  File "C:\Program Files (x86)\JetBrains\PyCharm 2016.1.2\helpers\pydev\_pydev_bundle\pydev_import_hook.py", line , in do_import
    module = self._system_import(name, *args, **kwargs)
  File "C:/Users/tianhang/PycharmProjects/WebApp\app_hyperlink\models.py", line , in <module>
    class Snippet(models.Model):
  File "C:\Python27\lib\site-packages\django\db\models\base.py", line , in __new__
    "INSTALLED_APPS." % (module, name)
RuntimeError: Model class app_hyperlink.models.Snippet doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

解决方法：在model添加 app_label = 'app_hyperlink'

class Snippet(models.Model):
    owner = models.ForeignKey('auth.User', related_name='snippet_user2')
    created = models.DateTimeField(auto_now_add=True)
    title = models.CharField(max_length=100, blank=True, default='')
    code = models.TextField()
    linenos = models.BooleanField(default=False)
    language = models.CharField(choices=LANGUAGE_CHOICES, default='python', max_length=100)
    style = models.CharField(choices=STYLE_CHOICES, default='friendly', max_length=100)

    class Meta:
        ordering = ('created',)
        app_label = 'app_hyperlink'