Django FileField 在上传后移动文件

围绕这一主题有几个问题，但我发现没有一个适合我想做的事情。我希望能够将文件上传到模型，并使用 pk 等模型实例属性将该文件保存在一个合适的位置。我知道这些东西会在之后设置model.save()所以我需要编写一个自定义保存来执行此操作，但我无法弄清楚。这是我所拥有的：

class UploadModel(models.Model):
    image = models.ImageField(upload_to='uploads')

    def save(self, *args, **kwargs):

        # Call standard save
        super(UploadModel, self).save(*args, **kwargs)

        if 'uploads' in self.image.path:

            initial_path = self.image.path

            # New path in the form eg '/images/uploadmodel/1/image.jpg'
            new_path = os.path.join(settings.MEDIA_ROOT, 'images', 
                self._meta.model_name, self.pk, os.path.basename(initial_path))

            # Create dir if necessary and move file
            if not os.path.exists(os.path.dirname(new_path)):
                makedirs(os.path.dirname(new_path))

            os.rename(initial_path, new_path)

            # Do something here to save the new file to the image field

            # Save changes
            super(UploadModel, self).save(*args, **kwargs)

我必须做什么image字段让它引用这个新文件位置，并为其设置所有有用的属性，例如image.path, image.name, image.url etc?

The docs https://docs.djangoproject.com/en/1.8/topics/files/#using-files-in-models说以上是我需要做的全部，但这只会导致image字段指向不存在的文件。我看过this https://stackoverflow.com/questions/5135556/dynamic-file-path-in-django相关问题并尝试了snippet https://djangosnippets.org/snippets/1129/在一个答案中提到，但我还没有找到解决方案。

经过大量搜索和发现后我发现了this https://code.djangoproject.com/ticket/15590#comment:10旧的文档票有很好的解释。

class UploadModel(models.Model):
    image = models.ImageField(upload_to='uploads')

    def save(self, *args, **kwargs):

        # Call standard save
        super(UploadModel, self).save(*args, **kwargs)

        if 'uploads' in self.image.path:

            initial_path = self.image.path

            # New path in the form eg '/images/uploadmodel/1/image.jpg'
            new_name = '/'.join(['images', self._meta.model_name, str(self.id), 
                path.basename(initial_path)])
            new_path = os.path.join(settings.MEDIA_ROOT, 'images', 
            self._meta.model_name, self.pk, os.path.basename(initial_path))

            # Create dir if necessary and move file
            if not os.path.exists(os.path.dirname(new_path)):
                makedirs(os.path.dirname(new_path))

            os.rename(initial_path, new_path)

            # Update the image_file field
            self.image_file.name = new_name

            # Save changes
            super(UploadModel, self).save(*args, **kwargs)

现在我读到了为此的文档 https://docs.djangoproject.com/en/1.8/topics/files/#using-files-in-models它看起来完全显而易见:)但我确实认为解释可以更具描述性。希望这会节省一些人的时间！