我的旧models.py:
from django.db import models
from taggit.managers import TaggableManager
from django.utils.encoding import smart_unicode
import markdown
class PublishedManager(models.Manager):
def get_query_set(self):
return super(PublishedManager, self).get_query_set().filter\
(is_published=True)
class Category(models.Model):
name = models.CharField(max_length=55)
def __unicode__(self):
return u"%s" %(self.name)
class BookMarks(models.Model):
name = models.CharField(max_length=255)
url = models.URLField()
date_time = models.DateTimeField(auto_now_add=True)
def __unicode__(self):
return u"%s %s %s" %(self.name, self.url, self.date_time)
class Post(models.Model):
title = models.CharField(max_length=255)
slug = models.SlugField(max_length=255, unique=True)
excerpt = models.TextField(blank=True, help_text="A small teaser of\
your content")
content = models.TextField(blank=True, null=True)
contentmarkdown = models.TextField()
date_created = models.DateTimeField(auto_now_add=True)
is_published = models.BooleanField(default=True)
objects = models.Manager()
published_objects = PublishedManager()
tags = TaggableManager()
category = models.ForeignKey(Category)
def save(self):
self.content = markdown.markdown(self.contentmarkdown)
super(Post, self).save() # Call the "real" save() method.
class Meta:
ordering = ("date_created",)
def __unicode__(self):
return smart_unicode("%s %s %s %s %s" %(self.title, self.content, self.is_published, self.category, self.tags))
def get_absolute_url(self):
return "/posts/%s/" % self.id
class Book(models.Model):
name = models.CharField(max_length=55)
author = models.CharField(max_length=55)
image = models.ImageField(upload_to="static/img/books/")
body = models.TextField(blank=True, null=True)
bodymarkdown = models.TextField()
def __unicode__(self):
return u"%s %s" %(self.name, self.author)
def get_absolute_url(self):
return "/books/%s/" % self
.id
并在将“category = models.ForeignKey（Category）”这个字段添加到Book和BookMarks表之后，我的新models.py就像这样：
from django.db import models
from taggit.managers import TaggableManager
from django.utils.encoding import smart_unicode
import markdown
class PublishedManager(models.Manager):
def get_query_set(self):
return super(PublishedManager, self).get_query_set().filter\
(is_published=True)
class Category(models.Model):
name = models.CharField(max_length=55)
def __unicode__(self):
return u"%s" %(self.name)
class BookMarks(models.Model):
name = models.CharField(max_length=255)
url = models.URLField()
date_time = models.DateTimeField(auto_now_add=True)
category = models.ForeignKey(Category)
def __unicode__(self):
return u"%s %s %s" %(self.name, self.url, self.date_time)
class Post(models.Model):
title = models.CharField(max_length=255)
slug = models.SlugField(max_length=255, unique=True)
excerpt = models.TextField(blank=True, help_text="A small teaser of\
your content")
content = models.TextField(blank=True, null=True)
contentmarkdown = models.TextField()
date_created = models.DateTimeField(auto_now_add=True)
is_published = models.BooleanField(default=True)
objects = models.Manager()
published_objects = PublishedManager()
tags = TaggableManager()
category = models.ForeignKey(Category)
def save(self):
self.content = markdown.markdown(self.contentmarkdown)
super(Post, self).save() # Call the "real" save() method.
class Meta:
ordering = ("date_created",)
def __unicode__(self):
return smart_unicode("%s %s %s %s %s" %(self.title, self.content, self.is_published, self.category, self.tags))
def get_absolute_url(self):
return "/posts/%s/" % self.id
class Book(models.Model):
name = models.CharField(max_length=55)
author = models.CharField(max_length=55)
image = models.ImageField(upload_to="static/img/books/")
body = models.TextField(blank=True, null=True)
bodymarkdown = models.TextField()
category = models.ForeignKey(Category)
def __unicode__(self):
return u"%s %s" %(self.name, self.author)
def get_absolute_url(self):
return "/books/%s/" % self.id
class Errors(models.Model):
name = models.CharField(max_length=255)
created = models.DateTimeField(auto_now_add=True)
body = models.TextField(blank=True, null=True)
bodymarkdown = models.TextField()
def __unicode__(self):
return self.name
def get_absolute_url(self):
return "/errors/%s/" % self.id
我用过南方。一切都顺利但是在这一行之后：
? 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()
>>> datetime.datetime.now()
我收到这样的错误：
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
utility.execute()
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
self.execute(*args, **options.__dict__)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/core/management/base.py", line 232, in execute
output = self.handle(*args, **options)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/management/commands/migrate.py", line 108, in handle
ignore_ghosts = ignore_ghosts,
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/__init__.py", line 213, in migrate_app
success = migrator.migrate_many(target, workplan, database)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 235, in migrate_many
result = migrator.__class__.migrate_many(migrator, target, migrations, database)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 310, in migrate_many
result = self.migrate(migration, database)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 133, in migrate
result = self.run(migration)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 106, in run
dry_run.run_migration(migration)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 191, in run_migration
self._run_migration(migration)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 178, in _run_migration
raise exceptions.FailedDryRun(migration, sys.exc_info())
south.exceptions.FailedDryRun: ! Error found during dry run of '0012_auto__del_field_book_category__add_field_book_category1__del_field_boo'! Aborting.
Traceback (most recent call last):
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 175, in _run_migration
migration_function()
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/migration/migrators.py", line 57, in <lambda>
return (lambda: direction(orm))
File "/home/ada/mainproject/blog/migrations/0012_auto__del_field_book_category__add_field_book_category1__del_field_boo.py", line 17, in forwards
keep_default=False)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/db/generic.py", line 44, in _cache_clear
return func(self, table, *args, **opts)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/db/generic.py", line 402, in add_column
sql = self.column_sql(table_name, name, field)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/south/db/generic.py", line 688, in column_sql
default = field.get_db_prep_save(default, connection=self._get_connection())
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/db/models/fields/related.py", line 991, in get_db_prep_save
connection=connection)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 292, in get_db_prep_save
prepared=False)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 284, in get_db_prep_value
value = self.get_prep_value(value)
File "/home/ada/virtualenv/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 537, in get_prep_value
return int(value)
TypeError: int() argument must be a string or a number, not 'datetime.datetime'
请告诉我为什么会收到此错误？我该怎么办？
答案 0 :(得分：1)
因为您的新类别字段是必填字段（您无法在不为其提供类别的情况下创建图书或书签），南方会询问您如何处理数据库中的现有图书和书签 - 您的最新更改将使您当前的图书/书签无效（因为他们没有类别）。
您的新类别字段使用类别表的主键在书籍/书签表中显示。该主键可能是整数（或可能是字符串）。
South要求您提供默认主键。而不是在数据库中提供类别对象的主键（可以是整数或字符串）。您已经提供了数据时对象。
当它实际运行迁移时它正在崩溃，因为该字段不包含datetime对象。它包含整数（或字符串）。您需要再次创建迁移并添加有效的主键。