具有当前实例 ID 的动态文件上传路径 [英] dynamic file upload path with current instance id

问题描述

我有一个获取当前登录用户、一些输入和一个文件的表单:

I have a form which gets current logged in user, some inputs and a file:

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

对于这个表格有一个看法:

For this form a have a view:

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，我正在使用 upload_to 功能.这是我的模态:

for this item's file field i am using upload_to feature. here is my modal:

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)

问题是我在上传的路径中看不到当前的实例 ID，因为以下行:

problem is that i can't see the current instance id in uploaded path because of following line:

item = item_form.save(commit=False)

它还没有实例 id，而是创建了 user_1/item_NONE/file 来代替当前的 item id

it has not instance id yet and instead of current item id it create user_1/item_NONE/file

如何将 id 设置为该路径?

how can i set id to this path?

提前致谢

推荐答案

这里 我发现了想法 &&基于使用 post_save 信号的代码，当创建的对象从临时目录移动到模型类中的指定目录时:

Here I've found idea && code based on using the post_save signal, when object created move from temp directory to specified one in model class:

use_key 和 upload_to 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文件，因此有可能被覆盖.upload_to 将简单地定义临时目录以将文件最初上传到.

use_key and upload_to are optional. use_key defaults to False. If it is True then the id of the instance will be used as a prefix for the new file as there is the potential for overwriting now that we are moving the file. upload_to will simply define the temporary directory to upload the files to initially.

from django.db.models import ImageField, FileField, signals
from django.dispatch import dispatcher
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)
        dispatcher.connect(self._move_image, signal=signals.post_save, sender=cls)

    def _move_image(self, instance=None):
        """
            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, 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)'


class Image(models.Model):
    file = CustomImageField(use_key=True, upload_to='tmp')

    def get_upload_to(self, attname):
        return 'path/to/{0}'.format(self.id)

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