Django学习笔记2
(11_env) D:\learning_log>python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying admin.0001_initial... OK
Applying admin.0002_logentry_remove_auto_add... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying auth.0007_alter_validators_add_error_messages... OK
Applying auth.0008_alter_user_username_max_length... OK
Applying auth.0009_alter_user_last_name_max_length... OK
Applying sessions.0001_initial... OK
windows(使用dir) 或者linux(ls) 可以看到当前文件夹下多了一个db.sqlite3启动服务器，查看系统中的项目
(11_env) D:\learning_log>python manage.py runserver
Performing system checks...
System check identified no issues (0 silenced).
March 29, 2018 - 23:34:01
Django version 1.8.4, using settings 'learning_log.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK. 打开浏览器输入http://localhost:8000/或
http://127.0.0.1:8000/可以看到shell中有如下信息，并且浏览器也会打开默认的项目
下面是2.0.3展示的html页面，我们1.8.4只有一个简陋的DEBUG=True的提示页面
创建应用程序
这里有人可能会对项目和应用程序区别不太懂，一起来看官网手册吧
Projects vs. apps
What’s the difference between a project and an app? An app is a Web application that does something – e.g., a Weblog system, a database of public records or a simple poll app. A project is a collection of configuration and apps for a particular website. A project can contain multiple apps. An app can be in multiple projects.
app是一个完成一些功能的web应用,project是一个特定的网站的配置集合与很多个应用程序。所以我们还要创建应用程序
另打开工作终端，激活虚拟环境，执行命令startapp
D:\learning_log>call 11_env/Scripts/activate.bat
(11_env) D:\learning_log>python manage.py startapp learning_logs
目录结构
learning_logs/
__init__.py
admin.py
apps.py
migrations/
__init__.py
models.py
tests.py
views.py
下面开始我们的实战部分 做一个简单的学习笔记应用
每位用户都需要在学习笔记中创建很多主题。用户输入的每个条目都与
特定的主体相关联，这些条目将以文本的方式显示。还要存储每个条目的时间戳，记录
用户创建的时间。
定义模型models.py
from django.db import models
# Create your models here. 定义模型
class Topic(models.Model):
"""用户学习的主题"""
text = models.CharField(max_length = 200)
data_added = models.DataTimeField(auto_now_add = True)
def __str__(self):
"""返回模型的字符串表示"""
return self.text
激活模型打开learning_log/learning_log中的settings.py
下面片段告诉哪些应用程序安装在项目中
# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
# 我的应用程序
'learning_logs',
]让Django修改数据库，使其能够存储与模型Topic相关的信息
(11_env) D:\learning_log>python manage.py makemigrations learning_logs
Migrations for 'learning_logs':
learning_logs\migrations\0001_initial.py
- Create model Topic
Django创建了一个迁徙文件0001_initial.py 这个文件在数据库中为模型Topic创建了一张表
应用这种迁徙，让Django替我们修改数据库
(11_env) D:\learning_log>python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, learning_logs, sessions
Running migrations:
Applying learning_logs.0001_initial... OK
Django管理网站
创建超级用户
(11_env) D:\learning_log>python manage.py createsuperuser
Username (leave blank to use 'clarence'): Clarence
Email address:
Password:
Password (again):
Superuser created successfully.
Django自动在管理网站中添加了一些模型，如User和Group,但对于我们常见的模型，必须进行手工注册
在我们创建应用程序learning_logs中models.py所在的目录有一个admin.py文件，我们在这里注册模型
from django.contrib import admin
# Register your models here.
# 向管理网站注册模型Topic
from learning_logs.models import Topic
admin.site.register(Topic)访问localhost:8000/admin/
添加了一条主题
定义模型Entry,每个条目都与特定的主题相关联，多对一的关系，即多个条目可关联到同一个主题
Entry继承了Django基类的Model.第一个属性topic是一个ForeignKey实例。
foreign key：一个表中的foreign key指向另一个表中的primary key，一张表中可以有多个外键
from django.db import models
# Create your models here. 定义模型
class Topic(models.Model):
"""用户学习的主题"""
text = models.CharField(max_length = 200)
data_added = models.DateTimeField(auto_now_add = True)
def __str__(self):
"""返回模型的字符串表示"""
return self.text
class Entry(models.Model):
"""Something specific learned about a topic."""
topic = models.ForeignKey(Topic)
text = models.TextField()
date_added = models.DateTimeField(auto_now_add=True)
class Meta:
verbose_name_plural = 'entries'
def __str__(self):
"""Return a string representation of the model."""
return self.text[:50] + "..."
(11_env) D:\learning_log>python manage.py makemigrations learning_logs
Migrations for 'learning_logs':
learning_logs\migrations\0002_entry.py
- Create model Entry
(11_env) D:\learning_log>python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, learning_logs, sessions
Running migrations:
Applying learning_logs.0002_entry... OK
向管理网站注册Entry 修改admin.py
from django.contrib import admin
# Register your models here.
# 向管理网站注册模型Topic
from learning_logs.models import Topic, Entry
admin.site.register(Topic)
admin.site.register(Entry)打开管理网站
