相关疑难解决方法(0)

我有一个Django应用程序,我想在其中将ForeignKey中的字段更改为ManyToManyField.我想保留我的旧数据.最简单/最好的流程是什么？如果重要,我使用sqlite3作为我的数据库后端.

如果我对问题的总结不清楚,这是一个例子.说我有两个型号:

class Author(models.Model):  
    author = models.CharField(max_length=100) 

class Book(models.Model):  
    author = models.ForeignKey(Author)  
    title = models.CharField(max_length=100)

假设我的数据库中有很多数据.现在,我想更改Book模型,如下所示:

class Book(models.Model):  
    author = models.ManyToManyField(Author)  
    title = models.CharField(max_length=100) 

我不想"丢失"我之前的所有数据.

完成此任务的最佳/最简单方法是什么？

肯

我正在尝试向我之前创建的ManyToMany字段添加订单.我基本上想订购图片集中的图片.我在Django 1.7上运行,所以没有更多的南迁移(我试图遵循这个教程:http://mounirmesselmeni.github.io/2013/07/28/migrate-django-manytomany-field-to-manytomany-through -with -南/)

这是我的"通过"关系:

class CollectionPictures(models.Model):
    picture = models.ForeignKey(
        Picture,
        verbose_name=u'Picture',
        help_text=u'Picture is included in this collection.',
    )
    collection = models.ForeignKey(
        Collection,
        verbose_name=u'Collection',
        help_text=u'Picture is included in this collection',
    )
    order = models.IntegerField(
        verbose_name=u'Order',
        help_text=u'What order to display this picture within the collection.',
        max_length=255
    )

    class Meta:
        verbose_name = u"Collection Picture"
        verbose_name_plural = u"Collection Pictures"
        ordering = ['order', ]

    def __unicode__(self):
        return self.picture.name + " is displayed in " + self.collection.name + (
        " in …

我有一个看起来像这样的模型：

class Assignment(models.Model):
    """An assignment covers a range of years, 
    has multiple coders and one specific task"""
    title = models.CharField(blank=True, max_length=100)
    start_date = models.DateField(default=date.today)
    end_date = models.DateField(default=date.today)
    coders = models.ManyToManyField(User, related_name='assignments')

我想改变这个模型（它有数据已经​​在生产中），使它看起来像这样：

class Assignment(models.Model):
    """An assignment covers a range of years, 
    has multiple coders and one specific task"""
    title = models.CharField(blank=True, max_length=100)
    start_date = models.DateField(default=date.today)
    end_date = models.DateField(default=date.today)
    coders = models.ManyToManyField(User, through = 'AssignmentProgress')

class AssignmentProgress(models.Model):
    """The progress a particular coder has made with an assignment"""
    assignment = models.ForeignKey(Assignment, related_name="assignment_progress") …