django part 1 ---models

windows mysql 安装
首先到百度上下载 mysql-5.6.24

E:\paython学习\setup\mysql-5.6.24-win32\bin>mysqld -install
Service successfully installed.

E:\paython学习\setup\mysql-5.6.24-win32\bin>net start mysql
MySQL 服务正在启动 .........
MySQL 服务已经启动成功。


E:\paython学习\setup\mysql-5.6.24-win32\bin>mysql -uroot
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.24 MySQL Community Server (GPL)

Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> create database poll default charset utf8;
Query OK, 1 row affected (0.02 sec)

mysql>

建立python与mysql之间的联系

安装 MySQL-python-1.2.4b4.win32-py2.7.exe

在linux上也要安装这个驱动  yum install python-mysql

django 建立工程和应用

E:\paython学习\pycharm>django-admin startproject mysite

E:\paython学习\pycharm>cd mysite

E:\paython学习\pycharm\mysite>django-admin startapp polls

建好后再用pychram打开进行编辑和coding

mysite.settings.py

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'polls',                                                               //增加polls应用
)

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',                             //更换数据库为mysql
        'NAME': 'poll',
        'HOST': '127.0.0.1',
        'USER': 'root',
        'PASSWORD': '',
        'PORT': '3306',
    }
}

建立models

from django.db import models
from django.utils import timezone
import datetime
# Create your models here.
class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date_published')

    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
    def __unicode__(self):
        return self.question_text

 class Choice(models.Model):
    question = models.ForeignKey(Question)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

    def __unicode__(self):
        return self.choice_text 

同步数据库

E:\paython学习\pycharm\mysite>python manage.py makemigrations polls              //建立迁移文件
Migrations for 'polls':
  0001_initial.py:
    - Create model Choice
    - Create model Question
    - Add field question to choice

E:\paython学习\pycharm\mysite>python manage.py migrate                           //迁移到数据库
Operations to perform:
  Synchronize unmigrated apps: staticfiles, messages
  Apply all migrations: admin, contenttypes, polls, auth, sessions
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Running migrations:
  Rendering model states... DONE
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... 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 polls.0001_initial... OK
  Applying sessions.0001_initial... OK

在本地mysql上查看

mysql> show tables;
Empty set (0.00 sec)

mysql> show tables;
+----------------------------+
| Tables_in_poll             |
+----------------------------+
| auth_group                 |
| auth_group_permissions     |
| auth_permission            |
| auth_user                  |
| auth_user_groups           |
| auth_user_user_permissions |
| django_admin_log           |
| django_content_type        |
| django_migrations          |
| django_session             |
| polls_choice               |
| polls_question             |
+----------------------------+
12 rows in set (0.00 sec)

可见的确写到数据库中了

在数据库中的操作可以在shell中执行试验

E:\paython学习\pycharm\mysite>python manage.py shell
Python 2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)] on wi
32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from django.utils import timezone
>>> from polls.models import Question, Choice
>>> Question.objects.all()
[]
>>> from django.utils import timezone
>>> q = Question(question_text="what's new",pub_date=timezone.now())
>>> q.save()
>>> q.id
1L
>>> q.pub_date
datetime.datetime(2015, 7, 10, 13, 21, 21, 781000, tzinfo=<UTC>)
>>> q.question_text = "what's up"
>>> q.save()>>> Question.objects.all()
[<Question: what's up>]
>>> Question.objects.filter(id=1)
[<Question: what's up>]
>>> current_year = timezone.now().year
>>> Question.objects.get(pub_date__year=current_year)
<Question: what's up>
>>> q = Question.objects.get(pk=1)
>>> q
<Question: what's up>
>>> q.choice_set.all()
[]
>>> q.choice_set.create(choice_text='NOT much',votes=0)
<Choice: NOT much>
>>> q.choice_set.create(choice_text='the sky', votes=0)
<Choice: the sky>
>>> c = q.choice_set.create(choice_text='just hacking again',votes=0)
>>> c.question
<Question: what's up>
>>> q.choice_set.all()
[<Choice: NOT much>, <Choice: the sky>, <Choice: just hacking again>]
>>> q.choice_set.count
<bound method RelatedManager.count of <django.db.models.fields.related.RelatedM
nager object at 0x015F9030>>
>>> q.choice_set.count()
3
>>> c = q.choice_set.filter(choice_text__startswith='just hacking')
>>> c.delete()

这边介绍了几种模型的创建和选择的方法，之后在视图逻辑中都会用的到，如何把数据写入数据库，如何读等等

question是choice的外键

一个question有好多个choice

可以通过question来访问choice，也可以通过question来创建choice，因为他们之间有约束关系