提炼 http://south.readthedocs.org/en/latest/tutorial/part1.html 官方手册里面的步骤  

在新项目中使用

  第一步创建项目   django-admin.py startproject LearnSouth
创建app django-admin.py startapp books
在learnSouth.settings中修改数据库 DATABASES = { 'default': { 'ENGINE': 'django.db.backends.sqlite3', # Add 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'. 'NAME': 'demo.db', # Or path to database file if using sqlite3. # The following settings are not used with sqlite3: 'USER': '', 'PASSWORD': '', 'HOST': '', # Empty for localhost through domain sockets or '127.0.0.1' for localhost through TCP. 'PORT': '', # Set to empty string for default. } } INSTALLED_APPS = ( 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'django.contrib.messages', 'django.contrib.staticfiles', # Uncomment the next line to enable the admin: # 'django.contrib.admin', # Uncomment the next line to enable admin documentation: # 'django.contrib.admindocs', 'south', 'LearnSouth', 'books', )
命令行执行导入数据库 ./manage.py syncdb       初始化迁移信息   ./manage.py schemamigration book --initial
执行完以后会在books目录下看到1个migrations文件夹。里面保存了 0001_initial.py 打开看一下。暂时里面没有数据       修改models.py文件内容   from django.db import models # Create your models here. class XiaoShuo(models.Model): create_date = models.DateTimeField(auto_created=True) public_date = models.DateTimeField(auto_now=True) title = models.CharField(max_length=128) contnet = models.CharField(max_length=512000) class Comment(models.Model): username = models.CharField(max_length=64) email = models.CharField(max_length=64) # email = models.EmailField()
执行 ./manage.py schemamigration books --auto
查看migrations目录。发现生成 0002_auto_add_xiaoshuo_add_comment.py文件。代码为   class Migration(SchemaMigration): def forwards(self, orm): # Adding model 'XiaoShuo' db.create_table(u'books_xiaoshuo', ( (u'id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('create_date', self.gf('django.db.models.fields.DateTimeField')()), ('public_date', self.gf('django.db.models.fields.DateTimeField')(auto_now=True, blank=True)), ('title', self.gf('django.db.models.fields.CharField')(max_length=128)), ('contnet', self.gf('django.db.models.fields.CharField')(max_length=512000)), )) db.send_create_signal(u'books', ['XiaoShuo']) # Adding model 'Comment' db.create_table(u'books_comment', ( (u'id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('username', self.gf('django.db.models.fields.CharField')(max_length=64)), ('email', self.gf('django.db.models.fields.CharField')(max_length=64)), )) db.send_create_signal(u'books', ['Comment']) def backwards(self, orm): # Deleting model 'XiaoShuo' db.delete_table(u'books_xiaoshuo') # Deleting model 'Comment' db.delete_table(u'books_comment') models = { u'books.comment': { 'Meta': {'object_name': 'Comment'}, 'email': ('django.db.models.fields.CharField', [], {'max_length': '64'}), u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}), 'username': ('django.db.models.fields.CharField', [], {'max_length': '64'}) }, u'books.xiaoshuo': { 'Meta': {'object_name': 'XiaoShuo'}, 'contnet': ('django.db.models.fields.CharField', [], {'max_length': '512000'}), 'create_date': ('django.db.models.fields.DateTimeField', [], {}), u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}), 'public_date': ('django.db.models.fields.DateTimeField', [], {'auto_now': 'True', 'blank': 'True'}), 'title': ('django.db.models.fields.CharField', [], {'max_length': '128'}) } } complete_apps = ['books']
修改models.py代码为 class XiaoShuo(models.Model): create_date = models.DateTimeField(auto_created=True) public_date = models.DateTimeField(auto_now=True) title = models.CharField(max_length=128) contnet = models.CharField(max_length=512000) class Comment(models.Model): username = models.CharField(max_length=64) email = models.CharField(max_length=64) # email = models.EmailField()
生成0003_auto_chg_field_comment_email.py import datetime from south.db import db from south.v2 import SchemaMigration from django.db import models class Migration(SchemaMigration): def forwards(self, orm): # Changing field 'Comment.email' db.alter_column(u'books_comment', 'email', self.gf('django.db.models.fields.EmailField')(max_length=75)) def backwards(self, orm): # Changing field 'Comment.email' db.alter_column(u'books_comment', 'email', self.gf('django.db.models.fields.CharField')(max_length=64)) models = { u'books.comment': { 'Meta': {'object_name': 'Comment'}, 'email': ('django.db.models.fields.EmailField', [], {'max_length': '75'}), u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}), 'username': ('django.db.models.fields.CharField', [], {'max_length': '64'}) }, u'books.xiaoshuo': { 'Meta': {'object_name': 'XiaoShuo'}, 'contnet': ('django.db.models.fields.CharField', [], {'max_length': '512000'}), 'create_date': ('django.db.models.fields.DateTimeField', [], {}), u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}), 'public_date': ('django.db.models.fields.DateTimeField', [], {'auto_now': 'True', 'blank': 'True'}), 'title': ('django.db.models.fields.CharField', [], {'max_length': '128'}) } } complete_apps = ['books']
执行 ./manage.py migrate books   些时数据库中是最新的数据了！！！     ********************************************************************************************************* 查看sqlite数据库中的内容
当前目录下建立或打开test.db数据库文件，并进入sqlite命令终端，以sqlite>前缀标识：
[cdms@cdms LearnSouth]$ sqlite3 demo.db
 
查看数据库文件信息命令(注意命令前带字符'.')：
sqlite>.database

查看所有表的创建语句：
sqlite>.schema
 *********************************************************************************************************     把修改后的模型合并到字段。      

在老项目中使用

  首先把south添加到install_apps变量中。   然后执行   ./manage.py syncdb
之后执行转换,south会假装执行合并过程 ./manage.py convert_to_south myapp
项目拷贝到其他机器上使用的过程中。如果修改提交。必须要执行 ./manage.py migrate myapp 0001 --fake   如果没有数据库的项目，则不需要以上步骤。只需要执行syncdb同步到db。      

数据迁移

  在实践项目中，对模型的的修改往往伴随数据的修改。   比如原有的用户表采用了明文密码。在新版本中需要修改为加密的密码。通常开发过程中需要后台和db的配合。   后台修改字段，db部分在修改。   这里south的强大之处就出来了。可以在代码中修改迁移数据。   注意：一定要备份数据库   下面说说使用demo   首先建立1个app   ./manager.py startapp book2
之后在模型里面添加数据 from django.db import models class User(models.Model): username = models.CharField(max_length=255) password = models.CharField(max_length=60) name = models.TextField()     初始化数据记录 ./manage.py schemamigration --initial book2     合并到数据库 ./manage.py migrate book2
添加数据 ./manage.py shell User.objects.create(username="andrew", password="ihopetheycantseethis", name="Andrew Godwin")
以上步骤模拟了在实际过程中第一版的开发和数据导入。 接下来更新版本。密码修改为加密部分。   首先修改模型   from django.db import models # Create your models here. import hashlib class User(models.Model): username = models.CharField(max_length=255) # password = models.CharField(max_length=60) password_salt = models.CharField(max_length=8, null=True) password_hash = models.CharField(max_length=40, null=True) name = models.TextField() def check_password(self, password): return hashlib.sha1(self.password_salt + password).hexdigest() == self.password_hash

执行合并数据库 ./manage.py schemamigration book2 --auto
下面是好玩的部分。新建1个数据迁移记录 ./manage.py datamigration book2 hash_passwords
在 migrations文件夹下面生成1份0003_hash_password.py文件。 修改forwards函数。   def forwards(self, orm): "Write your forwards methods here." # Note: Don't use "from appname.models import ModelName". # Use orm.ModelName to refer to models in this application, # and orm['appname.ModelName'] for models in other applications. import random, hashlib, string for user in orm.User.objects.all(): user.password_salt = "".join([random.choice(string.letters) for i in range(8)]) user.password_hash = hashlib.sha1(user.password_salt + user.password).hexdigest() user.save()
forwards函数里面。执行了修改密码，导入部分。 回退函数也修改   def backwards(self, orm): "Write your backwards methods here." raise RuntimeError("cannot reverse this migration.")
接下来删除models.py中原始的password字段。 执行合并   outekiMacBook-Air:LearnSouth watsy$ ./manage.py schemamigration book2 --auto /Users/watsy/Documents/code/gitoschina/python/LearnSouth/book2/models.py:7: DeprecationWarning: the sha module is deprecated; use the hashlib module instead import sha ? The field 'User.password' does not have a default specified, yet is NOT NULL. ? Since you are removing this field, you MUST specify a default ? value to use for existing rows. Would you like to: ? 1. Quit now, and add a default to the field in models.py ? 2. Specify a one-off value to use for existing columns now ? 3. Disable the backwards migration by raising an exception. ? Please select a choice: 2 ? Please enter Python code for your one-off default value. ? The datetime module is available, so you can do e.g. datetime.date.today() >>> "" - Deleted field password on book2.User Created 0004_auto__del_field_user_password.py. You can now apply this migration with: ./manage.py migrate book2     执行合并到数据库 outekiMacBook-Air:LearnSouth watsy$ ./manage.py migrate book2 /Users/watsy/Documents/code/gitoschina/python/LearnSouth/book2/models.py:7: DeprecationWarning: the sha module is deprecated; use the hashlib module instead import sha Running migrations for book2: - Migrating forwards to 0004_auto__del_field_user_password. > book2:0002_auto__add_field_user_password_salt__add_field_user_password_hash > book2:0003_hash_passwords - Migration 'book2:0003_hash_passwords' is marked for no-dry-run. > book2:0004_auto__del_field_user_password - Loading initial data for book2. Installed 0 object(s) from 0 fixture(s)
测试执行以后的数据库是否修改密码成功 outekiMacBook-Air:LearnSouth watsy$ ./manage.py shell >>> from book2.models import User >>> User.objects.get(id=1).check_password("258841679") True >>> User.objects.get(id=1).check_password("fakepass") False
测试修改成功～