jacksonon / mysite

Python Django

mysite

Python Django

pip3 install django
cd mysite
python3 manage.py runserver
open localhost:8000/blog

根据Django内模型生成对应的数据库表结构

➜  mysite git:(master) ✗ python3 manage.py makemigrations
Migrations for 'blog':
  blog/migrations/0001_initial.py
    - Create model BlogArticles

查看生成表的源码SQL语句

➜  mysite git:(master) ✗ python3 manage.py sqlmigrate blog 0001
BEGIN;
--
-- Create model BlogArticles
--
CREATE TABLE "blog_blogarticles" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "title" varchar(300) NOT NULL, "body" text NOT NULL, "publish" datetime NOT NULL, "author_id" integer NOT NULL REFERENCES "auth_user" ("id") DEFERRABLE INITIALLY DEFERRED);
CREATE INDEX "blog_blogarticles_author_id_ed798e23" ON "blog_blogarticles" ("author_id");
COMMIT;

真正创建数据库

➜  mysite git:(master) ✗ python3 manage.py migrate             
Operations to perform:
  Apply all migrations: admin, auth, blog, 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 admin.0003_logentry_add_action_flag_choices... 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 blog.0001_initial... OK
  Applying sessions.0001_initial... OK

创建超级管理员

➜  mysite git:(master) ✗ python3 manage.py createsuperuser
Username (leave blank to use 'dp'): admin
Email address: [e-mail]
Password: 
Password (again): 
The password is too similar to the email address.
Bypass password validation and create user anyway? [y/N]: y
Superuser created successfully.

遇到的问题

TypeError: init() missing 1 required positional argument: 'on_delete'

在django2.0后，定义外键和一对一关系的时候需要加on_delete选项，此参数为了避免两个表里的数据不一致问题，不然会报错：
TypeError: __init__() missing 1 required positional argument: 'on_delete'
举例说明：
user=models.OneToOneField(User)
owner=models.ForeignKey(UserProfile)
需要改成：
user=models.OneToOneField(User,on_delete=models.CASCADE) --在老版本这个参数（models.CASCADE）是默认值
owner=models.ForeignKey(UserProfile,on_delete=models.CASCADE) --在老版本这个参数（models.CASCADE）是默认值
参数说明：
on_delete有CASCADE、PROTECT、SET_NULL、SET_DEFAULT、SET()五个可选择的值
CASCADE：此值设置，是级联删除。
PROTECT：此值设置，是会报完整性错误。
SET_NULL：此值设置，会把外键设置为null，前提是允许为null。
SET_DEFAULT：此值设置，会把设置为外键的默认值。
SET()：此值设置，会调用外面的值，可以是一个函数。
一般情况下使用CASCADE就可以了。