我有一个django应用程序,里面有四个模型。我现在意识到,这些模型中的一个应该放在单独的应用程序中。我确实为迁移安装了south,但我不认为这是它可以自动处理的事情。如何将旧应用程序中的一个模型迁移到新应用程序中?
此外,请记住,我需要这是一个可重复的过程,以便我可以迁移生产系统等。
发布于 2009-08-11 06:40:17
模型与应用程序的耦合不是很紧密,所以移动起来相当简单。Django在数据库表的名称中使用应用程序名称,所以如果你想移动你的应用程序,你可以通过SQL ALTER TABLE
语句重命名数据库表,或者--更简单--只需在模型的Meta
类中使用db_table
parameter来引用旧名称。
如果到目前为止,您已经在代码中的任何地方使用了ContentTypes或泛型关系,那么您可能希望重命名指向正在移动的模型的contenttype的app_label
,以便保留现有的关系。
当然,如果您根本没有要保留的数据,最简单的做法是完全删除数据库表,然后再次运行./manage.py syncdb
。
发布于 2014-08-01 14:32:02
这个过程我现在已经决定了,因为我已经回到这里几次了,并决定将其正式化。
这最初是在Potr Czachur's answer和Matt Briançon's answer上构建的,使用South 0.8.4
步骤1.发现子外键关系
# Caution: This finds OneToOneField and ForeignKey.
# I don't know if this finds all the ways of specifying ManyToManyField.
# Hopefully Django or South throw errors if you have a situation like that.
>>> Cat._meta.get_all_related_objects()
[<RelatedObject: common:toy related to cat>,
<RelatedObject: identity:microchip related to cat>]
所以在这个扩展的例子中,我们发现了另一个相关的模型,比如:
# Inside the "identity" app...
class Microchip(models.Model):
# In reality we'd probably want a ForeignKey, but to show the OneToOneField
identifies = models.OneToOneField(Cat)
...
步骤2.创建迁移
# Create the "new"-ly renamed model
# Yes I'm changing the model name in my refactoring too.
python manage.py schemamigration specific create_kittycat --auto
# Drop the old model
python manage.py schemamigration common drop_cat --auto
# Update downstream apps, so South thinks their ForeignKey(s) are correct.
# Can skip models like Toy if the app is already covered
python manage.py schemamigration identity update_microchip_fk --auto
步骤3.源代码控制:到目前为止提交更改。
如果你遇到合并冲突,比如团队成员在更新的应用程序上编写迁移,这将使其更具可重复性。
步骤4.在迁移之间添加依赖关系。
基本上,create_kittycat
依赖于所有内容的当前状态,然后所有内容都依赖于create_kittycat
。
# create_kittycat
class Migration(SchemaMigration):
depends_on = (
# Original model location
('common', 'the_one_before_drop_cat'),
# Foreign keys to models not in original location
('identity', 'the_one_before_update_microchip_fk'),
)
...
# drop_cat
class Migration(SchemaMigration):
depends_on = (
('specific', 'create_kittycat'),
)
...
# update_microchip_fk
class Migration(SchemaMigration):
depends_on = (
('specific', 'create_kittycat'),
)
...
步骤5.我们想要进行的表重命名更改。
# create_kittycat
class Migration(SchemaMigration):
...
# Hopefully for create_kittycat you only need to change the following
# 4 strings to go forward cleanly... backwards will need a bit more work.
old_app = 'common'
old_model = 'cat'
new_app = 'specific'
new_model = 'kittycat'
# You may also wish to update the ContentType.name,
# personally, I don't know what its for and
# haven't seen any side effects from skipping it.
def forwards(self, orm):
db.rename_table(
'%s_%s' % (self.old_app, self.old_model),
'%s_%s' % (self.new_app, self.new_model),
)
if not db.dry_run:
# For permissions, GenericForeignKeys, etc to work properly after migrating.
orm['contenttypes.contenttype'].objects.filter(
app_label=self.old_app,
model=self.old_model,
).update(
app_label=self.new_app,
model=self.new_model,
)
# Going forwards, should be no problem just updating child foreign keys
# with the --auto in the other new South migrations
def backwards(self, orm):
db.rename_table(
'%s_%s' % (self.new_app, self.new_model),
'%s_%s' % (self.old_app, self.old_model),
)
if not db.dry_run:
# For permissions, GenericForeignKeys, etc to work properly after migrating.
orm['contenttypes.contenttype'].objects.filter(
app_label=self.new_app,
model=self.new_model,
).update(
app_label=self.old_app,
model=self.old_model,
)
# Going backwards, you probably should copy the ForeignKey
# db.alter_column() changes from the other new migrations in here
# so they run in the correct order.
#
# Test it! See Step 6 for more details if you need to go backwards.
db.alter_column('common_toy', 'belongs_to_id', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['common.Cat']))
db.alter_column('identity_microchip', 'identifies_id', self.gf('django.db.models.fields.related.OneToOneField')(to=orm['common.Cat']))
# drop_cat
class Migration(SchemaMigration):
...
def forwards(self, orm):
# Remove the db.delete_table(), if you don't at Step 7 you'll likely get
# "django.db.utils.ProgrammingError: table "common_cat" does not exist"
# Leave existing db.alter_column() statements here
db.alter_column('common_toy', 'belongs_to_id', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['specific.KittyCat']))
def backwards(self, orm):
# Copy/paste the auto-generated db.alter_column()
# into the create_kittycat migration if you need backwards to work.
pass
# update_microchip_fk
class Migration(SchemaMigration):
...
def forwards(self, orm):
# Leave existing db.alter_column() statements here
db.alter_column('identity_microchip', 'identifies_id', self.gf('django.db.models.fields.related.OneToOneField')(to=orm['specific.KittyCat']))
def backwards(self, orm):
# Copy/paste the auto-generated db.alter_column()
# into the create_kittycat migration if you need backwards to work.
pass
第6步。仅当您需要使用backwards()来工作并让KeyError向后运行时。
# the_one_before_create_kittycat
class Migration(SchemaMigration):
# You many also need to add more models to South's FakeORM if you run into
# more KeyErrors, the trade-off chosen was to make going forward as easy as
# possible, as that's what you'll probably want to do once in QA and once in
# production, rather than running the following many times:
#
# python manage.py migrate specific <the_one_before_create_kittycat>
models = {
...
# Copied from 'identity' app, 'update_microchip_fk' migration
u'identity.microchip': {
'Meta': {'object_name': 'Microchip'},
u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
'identifies': ('django.db.models.fields.related.OneToOneField', [], {to=orm['specific.KittyCat']})
},
...
}
第7步.测试它-对我有效的可能不足以满足您的实际情况:)
python manage.py migrate
# If you need backwards to work
python manage.py migrate specific <the_one_before_create_kittycat>
发布于 2013-12-13 18:07:16
因此,在South 0.8.1和Django 1.5.1上,使用来自上述@Potr的原始响应不适用于我。我在下面发布了对我有用的东西,希望能对其他人有所帮助。
from south.db import db
from south.v2 import SchemaMigration
from django.db import models
class Migration(SchemaMigration):
def forwards(self, orm):
db.rename_table('common_cat', 'specific_cat')
if not db.dry_run:
db.execute(
"update django_content_type set app_label = 'specific' where "
" app_label = 'common' and model = 'cat';")
def backwards(self, orm):
db.rename_table('specific_cat', 'common_cat')
db.execute(
"update django_content_type set app_label = 'common' where "
" app_label = 'specific' and model = 'cat';")
https://stackoverflow.com/questions/1258130
复制相似问题