如何將枕頭圖像object保存到Django ImageField？

Question

縮略圖有一個 Django model 像：

class Thumb(models.Model):
    thumb = models.ImageField(upload_to='uploads/thumb/', null=True, default=None)

視圖生成一個帶有pillow package 的縮略圖，並且應該將其保存在Thumb實例中，使用如下代碼：

image.thumbnail((50, 50))
inst.thumb.save('thumb.jpg', ???)

為inst.thumb.save制作image數據的正確方法是什么??? ？

我能夠讓下面的工作：

thumb_temp = NamedTemporaryFile()
image.save(thumb_temp, 'JPEG', quality=80)
thumb_temp.flush()
inst.thumb.save('thumb.jpg', File(thumb_temp))
thumb_temp.close()  # Probably required to ensure temp file delete at close

但是寫一個臨時文件只是為了將內部數據傳遞給inst.thumb.save似乎相當笨拙，所以我想知道是否有更優雅的方法來做到這一點。 Django class NamedTemporaryFile的文檔。

Answer 1

這是一個工作示例（Python3，django 1.11），它從Model.ImageField獲取圖像，使用 PIL (Pillow) 對其執行調整大小操作，然后將生成的文件保存到同一個 ImageField。 希望這應該很容易適應您必須對模型圖像進行的任何處理。

from io import BytesIO
from django.core.files.uploadedfile import InMemoryUploadedFile
from django.core.files.base import ContentFile
from PIL import Image

IMAGE_WIDTH = 100
IMAGE_HEIGHT = 100

def resize_image(image_field, width=IMAGE_WIDTH, height=IMAGE_HEIGHT, name=None):
    """
    Resizes an image from a Model.ImageField and returns a new image as a ContentFile
    """
    img = Image.open(image_field)
    if img.size[0] > width or img.size[1] > height:
        new_img = img.resize((width, height))
    buffer = BytesIO()
    new_img.save(fp=buffer, format='JPEG')
    return ContentFile(buffer.getvalue())

#assuming your Model instance is called `instance`
image_field = instance.image_field
img_name = 'my_image.jpg'
img_path = settings.MEDIA_ROOT + img_name

pillow_image = resize_image(
                  image_field,
                  width=IMAGE_WIDTH,
                  height=IMAGE_HEIGHT,
                  name=img_path)

image_field.save(img_name, InMemoryUploadedFile(
     pillow_image,       # file
     None,               # field_name
     img_name,           # file name
     'image/jpeg',       # content_type
     pillow_image.tell,  # size
     None)               # content_type_extra
)

Answer 2

您可以為您的模型創建 pre_save 接收器：

from io import BytesIO
from functools import partial
from django.db import models
from django.core.files.uploadedfile import InMemoryUploadedFile
from PIL import Image

class Article(models.Model):
    title = models.CharField(max_length=120)
    slug = models.SlugField(max_length=120, unique=True)
    image = models.ImageField(
        upload_to=upload_image_location
    )
    thumbnail_image = models.ImageField(
        upload_to=partial(upload_image_location, thumbnail=True), 
        editable=False, blank=True
    )

    def create_thumbnail(self):
        image = Image.open(self.image.file.file)
        image.thumbnail(size=(310, 230))
        image_file = BytesIO()
        image.save(image_file, image.format)
        self.thumbnail_image.save(
            self.image.name,
            InMemoryUploadedFile(
                image_file,
                None, '',
                self.image.file.content_type,
                image.size,
                self.image.file.charset,
            ),
            save=False
        )

@receiver(models.signals.pre_save, sender=Article)
def prepare_images(sender, instance, **kwargs):
    if instance.pk:
        try:
            article = Article.objects.get(pk=instance.pk)
            old_image = article.image
            old_thumbnail_image = article.thumbnail_image
        except Article.DoesNotExist:
            return
        else:
            new_image_extension = os.path.splitext(instance.image.name)[1]
            if old_image and not old_image.name.endswith(new_image_extension):
                old_image.delete(save=False)
                old_thumbnail_image.delete(save=False)

    if not instance.thumbnail_image or not instance.image._committed:
        instance.create_thumbnail()

圖像的縮略圖是使用Pillow在create_thumbnail方法中創建的。 此方法適用於django-storages並將縮略圖保存在自定義存儲中，名稱為“article_slug_thumbnail.jpeg”。

我的 upload_image_location 方法：

def upload_image_location(instance, filename, thumbnail=False):
    _, ext = os.path.splitext(filename)
    return f'articles/{instance.slug}{f"_thumbnail" if thumbnail else ""}{ext}'

Answer 3

class Profile(models.Model):
user = models.OneToOneField(User,on_delete=models.CASCADE)
image = models.ImageField(default = 'default.jpg',upload_to='profile_pics')

def __str__(self):
    return f'{self.user.username} Profile'
def save(self):
    super().save()

    img = Image.open(self.image.path)
    if img.height >300 or img.width >300:
        oputput_size = (300,300)
        img.thumbnail(oputput_size)
        img.save(self.image.path)

Answer 4

from io import BytesIO
from PIL import Image
from django.core.files.images import ImageFile
import requests

img_url = 'https://cdn.pixabay.com/photo/2021/08/25/20/42/field-6574455__340.jpg'

res = Image.open(requests.get(img_url, stream=True).raw)
filename = 'sample.jpeg'
img_object= ImageFile(BytesIO(res.fp.getvalue()), name=filename)

// django_image_field = img_object