数据迁移

迁移的概念：就是将模型映射到数据库的过程

生成迁移文件：python manage.py makemigrations

执行迁移：python manage.py migrate

注

不需要初始化迁移文件夹，每个应用默认有迁移文件夹migrations

基本视图

pytnon
#首先我们在views.py中建立一个路由响应函数

from django.http import HttpResponse
def welcome(request):
    return HttpResponse('HelloDjango');
    
#接着我们在urls中进行注册
#1.直接访问视图
path(r'hello/',hello,name='hello'),

#2.导入App中的子路由urls.py文件
path('app/',include('App.urls'))

#3.使用命名空间(后面讲解)
path('app/',include(('App.urls','App'),namespace='App'))

#子路由写法如下：
urlpatterns =[

#django1.8,2.0正则表达式写法：不再使用，不推荐
#url(r'^index/$',index),

#Djangov2.0,v3.0,v4.0写法：常用
path(r'hello/',hello,name='hello'),
]

注意

如果使用IDE创建工程时同时创建了应用，可能IDE自动在settings.py定义了应用，不要重复定义，不然在启动服务时可能会报下面的错误：

shell
Watching for file changes with StatReloader
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "E:\Python\Conda\envs\Django\lib\threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "E:\Python\Conda\envs\Django\lib\threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\utils\autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\core\management\commands\runserver.py", line 125, in inner_run
    autoreload.raise_last_exception()
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\utils\autoreload.py", line 87, in raise_last_exception
    raise _exception[1]
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\core\management\__init__.py", line 394, in execute
    autoreload.check_errors(django.setup)()
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\utils\autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "E:\Python\Conda\envs\Django\lib\site-packages\django\apps\registry.py", line 93, in populate
    raise ImproperlyConfigured(
django.core.exceptions.ImproperlyConfigured: Application labels aren't unique, duplicates: user

目录

数据迁移

基本视图