你可以为你的模型创建 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()
使用Pillow库在create_thumbnail
方法中创建图像的缩略图。此方法与django-storages很好地配合使用,并将缩略图保存在名称为“article_slug_thumbnail.jpeg”的自定义存储中。
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}'
PIL.Image
上的read
方法。 - Escher