Django 具有当前实例id的动态文件上载路径

我有一个表格，其中包含当前登录用户、一些输入和一个文件：

class AddItemForm(ModelForm):
    class Meta:
        model = Item
        exclude = ['user']

对于此表单，请查看：

item_form = AddItemForm(request.POST, request.FILES)
if item_form.is_valid():
    item = item_form.save(commit=False)
    item.user = request.user
    item.save()

对于此项目的文件字段，我使用上载功能。以下是我的观点：

class Item(models.Model):
    user = models.ForeignKey(User)
    cover_image = models.FileField(upload_to=get_upload_path)

def get_upload_path(instance, filename):

    return "items/user_{user_id}/item_{item_id}/{filename}".format(user_id=instance.user.id, item_id=instance.id,filename=filename)

问题是，我无法在上载路径中看到当前实例id，因为以下行：

item = item_form.save(commit=False)

它还没有实例id，而是创建了user\u 1/item\u NONE/file来代替当前的item id

如何设置此路径的id

提前感谢

我找到了基于使用post_保存信号的想法和代码，当创建的对象从临时目录移动到模型类中的指定目录时：

使用密钥和上传密钥是可选的。use_key默认为False。如果为True，则实例的id将用作新文件的前缀，因为现在我们正在移动该文件，因此有可能被覆盖。upload_to将简单地定义文件最初上载到的临时目录

---

更新至django新版本的新使用方式信号：

from django.db.models import ImageField, FileField, signals
from django.conf import settings
import shutil, os, glob, re
from distutils.dir_util import mkpath

class CustomImageField(ImageField):
    """Allows model instance to specify upload_to dynamically.

    Model class should have a method like:

        def get_upload_to(self, attname):
            return 'path/to/{0}'.format(self.id)
    """
    def __init__(self, *args, **kwargs):
        kwargs['upload_to'] = kwargs.get('upload_to', 'tmp')

        try:
            self.use_key = kwargs.pop('use_key')
        except KeyError:
            self.use_key = False

        super(CustomImageField, self).__init__(*args, **kwargs)

    def contribute_to_class(self, cls, name):
        """Hook up events so we can access the instance."""
        super(CustomImageField, self).contribute_to_class(cls, name)
        signals.post_save.connect(self._move_image, sender=cls)

    def _move_image(self, instance, **kwargs):
        """
            Function to move the temporarily uploaded image to a more suitable directory 
            using the model's get_upload_to() method.
        """
        if hasattr(instance, 'get_upload_to'):
            src = getattr(instance, self.attname)
            if src:
                m = re.match(r"%s/(.*)" % self.upload_to, str(src))
                if m:
                    if self.use_key:
                        dst = "%s/%d_%s" % (instance.get_upload_to(self.attname), instance.id, m.groups()[0])
                    else:
                        dst = "%s/%s" % (instance.get_upload_to(self.attname), m.groups()[0])
                    basedir = "%s/%s/" % (settings.MEDIA_ROOT, os.path.dirname(dst))
                    mkpath(basedir)
                    shutil.move("%s/%s" % (settings.MEDIA_ROOT, src),"%s/%s" % (settings.MEDIA_ROOT, dst))
                    setattr(instance, self.attname, dst)
                    instance.save()

    def db_type(self):
        """Required by Django for ORM."""
        return 'varchar(100)'

---

您不能在

get\u upload\u path

中为新记录使用

instance.id

，因为此时尚未分配属性。它仅在更新现有记录时起作用。

from django.db.models import ImageField, FileField, signals
from django.conf import settings
import shutil, os, glob, re
from distutils.dir_util import mkpath

class CustomImageField(ImageField):
    """Allows model instance to specify upload_to dynamically.

    Model class should have a method like:

        def get_upload_to(self, attname):
            return 'path/to/{0}'.format(self.id)
    """
    def __init__(self, *args, **kwargs):
        kwargs['upload_to'] = kwargs.get('upload_to', 'tmp')

        try:
            self.use_key = kwargs.pop('use_key')
        except KeyError:
            self.use_key = False

        super(CustomImageField, self).__init__(*args, **kwargs)

    def contribute_to_class(self, cls, name):
        """Hook up events so we can access the instance."""
        super(CustomImageField, self).contribute_to_class(cls, name)
        signals.post_save.connect(self._move_image, sender=cls)

    def _move_image(self, instance, **kwargs):
        """
            Function to move the temporarily uploaded image to a more suitable directory 
            using the model's get_upload_to() method.
        """
        if hasattr(instance, 'get_upload_to'):
            src = getattr(instance, self.attname)
            if src:
                m = re.match(r"%s/(.*)" % self.upload_to, str(src))
                if m:
                    if self.use_key:
                        dst = "%s/%d_%s" % (instance.get_upload_to(self.attname), instance.id, m.groups()[0])
                    else:
                        dst = "%s/%s" % (instance.get_upload_to(self.attname), m.groups()[0])
                    basedir = "%s/%s/" % (settings.MEDIA_ROOT, os.path.dirname(dst))
                    mkpath(basedir)
                    shutil.move("%s/%s" % (settings.MEDIA_ROOT, src),"%s/%s" % (settings.MEDIA_ROOT, dst))
                    setattr(instance, self.attname, dst)
                    instance.save()

    def db_type(self):
        """Required by Django for ORM."""
        return 'varchar(100)'