Python Pillow:将图像渐进式保存到模型

Question

我之前问了一个关于pillow的相关问题。

Python Pillow: Make image progressive before sending to 3rd party server

只是扩展一下，当我上传图像并将其存储在服务器上时，我如何在图像中实现progressiveness？

Models.py

class Blog(models.Model):
    banner = models.FileField("banner", upload_to='blog_banner', help_text='Upload blog banner', blank=True, null=True)

Forms.py

def clean(self):
        data = self.cleaned_data
        banner = data['banner']

        # Check and make banner image progressive
        if not Utils.is_progressive_img(banner):
            data['banner'] = Utils.make_progressive_img(banner)

渐进法

img = Image.open(source)
progressive_img = StringIO()
img.save(progressive_img, "JPEG", quality=80, optimize=True, progressive=True)

在forms.py中，当我保存博客帖子时，我看到以下错误，我知道这是由于StringIO()的格式造成的

错误

AttributeError at /blog/create/
StringIO instance has no attribute '_committed'

Answer 1

下面是我在forms.py中使用的解决方案

forms.py

def clean(self):
    data = self.cleaned_data
    banner = data['banner']

    # Blog banner has been changed, Check for if the new image is progressive?
    if self.instance.banner != banner and Utils.is_progressive_img(banner) is False:
        progressive_banner = Utils.make_progressive_img(img=banner, method=2)
        data['banner'].file = progressive_banner

   return data

您需要更新Django FileField的.file属性

models.py

class Blog(models.Model):
    banner = models.FileField("banner", upload_to='blog_banner', help_text='Upload blog banner', blank=True, null=True)

更新

在model.save()中实现相同的逻辑

if Utils.is_progressive_img(self.banner) is False:
     progressive_banner = Utils.make_progressive_img(img=self.banner, method=2)

     name = self.banner.name
     # Delete the current image & Add the new progressive image.
     self.banner.delete(save=False)
     self.banner.save(name,content=ContentFile(progressive_banner.getvalue()), save=False)