如果没有给出图像，则 Django 模型函数保存图像字段 = 异常

Posted 2023-05-07

【中文标题】如果没有给出图像，则 Django 模型函数保存图像字段 = 异常

【英文标题】：Django model function to save ImageField if none image given = execption

【发布时间】：2019-03-31 19:05:22

【问题描述】：

我有一个 Django 模型函数来正确保存图像。目前看来 Django-SmartFields 在那一点上有问题，请参阅：https://github.com/lehins/django-smartfields/issues/17 并且 sorl 无法正常工作，不知道为什么。 所以我很快写下了这个：

models.py

class Post(models.Model):
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    title = models.CharField(verbose_name="Title", max_length=40)
    content = models.TextField(verbose_name="Content", max_length=5000)
    tag = models.CharField(verbose_name="Tags/Meta - (sep. by comma)", max_length=50, blank=True)
    category = models.ForeignKey(Category, verbose_name="Category", on_delete=models.CASCADE, null=True)
    postattachment = fields.FileField(
        verbose_name="Attachment",
        blank=True,
        null=True,
        upload_to=get_file_path_user_uploads,
        validators=[file_extension_postattachment, file_size_postattachment]
    )
    postcover = fields.ImageField(
        verbose_name="Cover",
        blank=True,
        null=True,
        upload_to=get_file_path_user_uploads,
        validators=[default_image_size, default_image_file_extension]
    )
    up_vote = models.IntegerField(verbose_name='Post Up-Vote(s)', default=0)
    down_vote = models.IntegerField(verbose_name='Post Down-Vote(s)', default=0)
    published_date = models.DateField(auto_now_add=True, null=True)

    def save(self, *args, **kwargs):
        imageTemproary = Image.open(self.postcover)
        outputiostream = BytesIO()
        imageTemproaryResized = imageTemproary.resize((700, 525))
        imageTemproaryResized.save(outputIoStream, format='JPEG', quality=85)
        outputIoStream.seek(0)
        self.postcover = InMemoryUploadedFile(outputIoStream, 'ImageField',
                                                  "%s.jpeg" % self.postcover.name.split('.')[0], 'image/jpeg',
                                                  sys.getsizeof(outputIoStream), None)
        super(Post, self).save(*args, **kwargs)

但如果我现在想通过我的表单清除图片，我会收到以下错误：

“postcover”属性没有与之关联的文件。

完整的跟踪：

 Internal Server Error: /post/1/edit/
 Traceback (most recent call last):
   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
     response = get_response(request)
  File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = self.process_exception_by_middleware(e, request)
   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 124, in _get_response
     response = wrapped_callback(request, *callback_args, **callback_kwargs)
   File "/app/app_Accounts/decorators.py", line 33, in _wrapped_view
     return view_func(request, *args, **kwargs)
   File "/usr/local/lib/python3.6/site-packages/ratelimit/decorators.py", line 30, in _wrapped
     return fn(*args, **kw)
   File "/app/app/views.py", line 473, in post_edit
     post.save()
   File "/app/app/models.py", line 173, in save
     imageTemproary = Image.open(self.postcover)
   File "/usr/local/lib/python3.6/site-packages/PIL/Image.py", line 2638, in open
     fp.seek(0)
   File "/usr/local/lib/python3.6/site-packages/django/core/files/utils.py", line 20, in <lambda>
     seek = property(lambda self: self.file.seek)
   File "/usr/local/lib/python3.6/site-packages/django/db/models/fields/files.py", line 41, in _get_file
     self._require_file()
   File "/usr/local/lib/python3.6/site-packages/django/db/models/fields/files.py", line 38, in _require_file
     raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
ValueError: The 'postcover' attribute has no file associated with it.

确实。对此行为有快速解决方法吗？

提前谢谢

【问题讨论】：

请显示您的错误堆栈跟踪和models.py的全部内容

我刚刚更新了帖子

【参考方案1】：

为什么你不能检查图像是否存在

import os //added
def save(self, *args, **kwargs):
     super(Post, self).save(*args, **kwargs)
     if self.postcover:
         if os.path.exists(self.postcover.path):     //this was added
            imageTemproary = Image.open(self.postcover)
            outputIoStream = BytesIO()
            imageTemproaryResized = imageTemproary.resize((700, 525))
            imageTemproaryResized.save(outputIoStream, format='JPEG', quality=85)
            outputIoStream.seek(0)
            self.postcover = InMemoryUploadedFile(outputIoStream, 'ImageField',
                                                  "%s.jpeg" % self.postcover.name.split('.')[0], 'image/jpeg',
                                                  sys.getsizeof(outputIoStream), None)
     super(Post, self).save(*args, **kwargs)

【讨论】：

@Venom 对不起什么？只需用上面的替换模型保存

好吧，我做到了；）但没有任何改变。我可以将新图像保存到现场，但我无法清除其中的数据......所以我仍然和以前一样......首先很抱歉造成误解。到目前为止，谢谢。

好的，这再次以某种方式有所帮助，我能够保存该字段，但图像不会调整大小或转换为 jpeg。现在它的反应就像我根本不会使用你的台词......就像 Django Build-In 流程

似乎如果 os.path.exists(self.postcover.url) 无法访问

@Venom 它不是 url 它的路径