Django app2

小咪咪 2021-10-18 11:58 219阅读 0赞

### Django app2 ###

*  前言
 *   *  migrate
     *  polls/models.py
     *  配置模型
     *  启动
 *  polls/admin.py
 *   *  参考博客

# 前言 #

这部分将使用数据库，Django 默认的是sqlite3，如果需要修改数据库的配置，在创建的Django的项目下的settings.py文件下修改配置

DATABASES = { 
       'default': { 
           'ENGINE': 'django.db.backends.sqlite3',
           # 'django.db.backends.postgresql',
           # 'django.db.backends.mysql',
           # 'django.db.backends.oracle'
           'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
       }
    }

修改ENGINE的内容，如 ‘django.db.backends.postgresql’, ‘django.db.backends.mysql’, or ‘django.db.backends.oracle’  
sqlite3是Django内置的，操作简单

## migrate ##

py manage.py migrate

migrate命令查看已安装的应用程序设置，并根据mysite/settings.py文件中的数据库设置和应用程序附带的数据库迁移创建任何必要的数据库表（稍后我们将介绍这些）

## polls/models.py ##

在该文件定义需要的模型 Question和Choice

from django.db import models
    
    # Create your models here.
    
    
    class Question(models.Model):
    	# 该类是django.db.models.Model的子类
        question_text = models.CharField(max_length=200)
        # question_text 类变量与数据库的字段对应
        # CharField 表示是char的数据字段类型
        # max_length 表示字符类型存储的最长长度
        pub_date = models.DateTimeField('date published')
    	# DateTimeField是时间字段类型
    
    class Choice(models.Model):
        question = models.ForeignKey(Question, on_delete=models.CASCADE)
        # ForeignKey 定义外键关系
        choice_text = models.CharField(max_length=200)
        votes = models.IntegerField(default=0)
        # default 表示默认值

## 配置模型 ##

在创建的Django的项目下的settings.py文件下找到INSTALLED\_APPS 并添加 ‘polls.apps.PollsConfig’

INSTALLED_APPS = [
        'polls.apps.PollsConfig',# 添加该配置信息
        'django.contrib.admin',
        'django.contrib.auth',
        'django.contrib.contenttypes',
        'django.contrib.sessions',
        'django.contrib.messages',
        'django.contrib.staticfiles',
    ]

并在命令行运行(数据迁移)

py manage.py makemigrations polls

并得到

Migrations for 'polls':
      polls\migrations\0001_initial.py
        - Create model Choice
        - Create model Question
        - Add field question to choice

通过该命令会生成一个文件 polls/migrations/0001\_initial.py

将模型生成sql

py manage.py sqlmigrate polls 0001

执行该命令应该得到

BEGIN;
    --
    -- Create model Choice
    --
    CREATE TABLE "polls_choice" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "choice_text" varchar(200)
     NOT NULL, "votes" integer NOT NULL);
    --
    -- Create model Question
    --
    CREATE TABLE "polls_question" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "question_text" 
    varchar(200) NOT NULL, "pub_date" datetime NOT NULL);
    --
    -- Add field question to choice
    --
    ALTER TABLE "polls_choice" RENAME TO "polls_choice__old";
    CREATE TABLE "polls_choice" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "choice_text" varchar(200)
     NOT NULL, "votes" integer NOT NULL, "question_id" integer NOT NULL REFERENCES "polls_question" ("id") 
     DEFERRABLE INITIALLY DEFERRED);
    INSERT INTO "polls_choice" ("id", "choice_text", "votes", "question_id") SELECT "id", "choice_text", 
    "votes", NULL FROM "polls_choice__old";
    DROP TABLE "polls_choice__old";
    CREATE INDEX "polls_choice_question_id_c5b4b260" ON "polls_choice" ("question_id");
    COMMIT;

python manage.py check 
     # 检查sql命令

py manage.py migrate
    # 重新运行
    # 将上面变化重新加载到数据库中

注册管理员用户

py manage.py createsuperuser

类似下面

Username: admin
    Email address: admin@polls.com
    Password:
    Password (again):
    # 输入密码的时候可能会出现字符未显示的情况，解决：直接输入就行，不管字符显示问题（我用pycharm遇到的情况）
    This password is too short. It must contain at least 8 characters.
    This password is too common.
    This password is entirely numeric.
    Bypass password validation and create user anyway? [y/N]: y
    Superuser created successfully.

## 启动 ##

py manage.py runserver

在浏览器的地址栏输入http://127.0.0.1:8000/admin/  
输入刚才注册的用户名与密码

运行截图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTQ2NjUw_size_16_color_FFFFFF_t_70]

# polls/admin.py #

在该文件创建polls对象

from django.contrib import admin
    
    from .models import Question
    
    admin.site.register(Question)

刷新刚才的网页出现  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTQ2NjUw_size_16_color_FFFFFF_t_70 1]

## 参考博客 ##

[Django表单][Django]  
[Django传值][Django 1]  
[用python专业版创建Django项目][python_Django]  
[Django创建一个应用项目][Django 2]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTQ2NjUw_size_16_color_FFFFFF_t_70 1]: /images/20211018/123a32ca2cdb486ea3a1188b0e843a13.png
[Django]: https://blog.csdn.net/qq_41146650/article/details/93660292
[Django 1]: https://blog.csdn.net/qq_41146650/article/details/93656232
[python_Django]: https://blog.csdn.net/qq_41146650/article/details/93654205
[Django 2]: https://blog.csdn.net/qq_41146650/article/details/99232683