Django保存重写ImageField处理 [英] Django save override ImageField handling

问题描述

在此线程发生问题后，有当我使用Django Admin时，我的models.py仍然是个大问题。这是我的代码（我删除了与我的问题无关的东西）：

After the problems I had on this thread, there is still a big problem in my models.py when I'm using the Django Admin. Here is my code (I removed stuff non related to my problem) :

from django.core.files.uploadedfile import InMemoryUploadedFile
from PIL import Image as Img
import StringIO

class Mymodel(models.Model):
        photo = models.ImageField(upload_to="photo/", blank=True, null=True)

        def save(self, *args, **kwargs):    
            width = 500
            height = 500
            size = (width,height)

            if self.photo:
                image = Img.open(StringIO.StringIO(self.photo.read()))
                (imw, imh) = image.size
                if (imw>width) or (imh>height) :
                    image.thumbnail(size, Img.ANTIALIAS)

                #If RGBA, convert transparency
                if image.mode == "RGBA":
                    image.load()
                    background = Img.new("RGB", image.size, (255, 255, 255))
                    background.paste(image, mask=image.split()[3]) #3 is alpha channel
                    image=background


                output = StringIO.StringIO()
                image.save(output, format='JPEG', quality=60)
                output.seek(0)
                self.photo = InMemoryUploadedFile(output,'ImageField', "%s.jpg" %self.photo_principale.name.split('.')[0], 'image/jpeg', output.len, None)

            try:
                this = Mymodel.objects.get(id=self.id)
                if this.photo != self.photo:
                    this.photo.delete(save=False)
            except: pass # when new photo then we do nothing, normal case 

            super(Mymodel, self).save(*args, **kwargs)

它的工作原理是，文件上传，调整大小，并在需要时成功转换为JPEG。这个问题，每当我编辑它，即使没有上传新的图像，它也会创建一个新的图像（例如，我第一次使用图像hello.jpg保存我的模型，然后编辑它，它会创建即使我没有上传任何东西，也称为hello_1.jpg。
我以为try / except块只能在编辑时工作（所以没有新的文件上传），但显然不是。

It works, the files are uploaded, resized and converted to JPEG successfully when needed. The problem, every time I edit it, even when NOT uploading a new image, it creates a new image (for example, I save my model a first time with image "hello.jpg", then I edit it, it'll create a new image called "hello_1.jpg" even if I didn't upload anything). I thought the try/except block would work when only editing (so no new file upload), but apparently not.

提前感谢帮助： ）

推荐答案

为我工作的最终解决方案：

Final solution, working for me :

from django.core.files.uploadedfile import InMemoryUploadedFile
from PIL import Image as Img
import StringIO
from django.db.models.signals import post_delete
from django.dispatch import receiver

Class Mymodel(models.Model):
  photo= models.ImageField(upload_to="photo/", blank=True, null=True)

  def save(self, *args, **kwargs):
        width = 500
        height = 500
        size = (width,height)
        isSame = False
        if self.photo:
            try:
                this = Mymodel.objects.get(id=self.id)
                if this.photo==self.photo :
                    isSame= True
            except: pass # when new photo then we do nothing, normal case

            image = Img.open(StringIO.StringIO(self.photo.read()))
            (imw, imh) = image.size
            if (imw>width) or (imh>height) :
                image.thumbnail(size, Img.ANTIALIAS)

            #If RGBA, convert transparency
            if image.mode == "RGBA":
                image.load()
                background = Img.new("RGB", image.size, (255, 255, 255))
                background.paste(image, mask=image.split()[3]) # 3 is the alpha channel
                image=background


            output = StringIO.StringIO()
            image.save(output, format='JPEG', quality=60)
            output.seek(0)
            self.photo = InMemoryUploadedFile(output,'ImageField', "%s.jpg" %self.photo.name.split('.')[0], 'image/jpeg', output.len, None)

        try:
            this = Mymodel.objects.get(id=self.id)
            if this.photo==self.photo or isSame :
                self.photo=this.photo
            else :
                this.photo.delete(save=False)
        except: pass # when new photo then we do nothing, normal case 

        super(Mymodel, self).save(*args, **kwargs)

@receiver(post_delete, sender=Mymodel)
def photo_post_delete_handler(sender, **kwargs):
    instance = kwargs['instance']
    storage, path = instance.photo.storage, instance.photo.path
    if (path!='.') and (path!='/') and (path!='photo/') and (path!='photo/.'):
        storage.delete(path)

希望可以帮助某人;）

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