[英]Django: Using ImageFields in other apps?
我有一些可以上傳圖片的應用。 既然每個應用程序中都多次出現幾乎相同的代碼,我希望從名為images的應用程序中加載圖像。 是否可以連接其他應用程序,以便它們使用app1 [images] ShareImage類的ImageFields?
如果沒有,我如何使用方法image_resize和兩個@receiver函數,以便它們可以被多個應用程序使用,而且我只有一個代碼:
我曾經嘗試過遺傳,但是我無法擺脫它。
我也嘗試通過Import將ImageFields導入另一個類。
APP1:
import os
from io import BytesIO
from PIL import Image
from django.db import models
from django.dispatch import receiver
from django.core.files.base import ContentFile
from .storage import OverwriteStorage
class ShareImage(models.Model):
image = models.ImageField(
upload_to='images/',
verbose_name='Bild',
storage=OverwriteStorage(),
)
thumbnail = models.ImageField(
upload_to='images/',
editable=False,
storage=OverwriteStorage(),
)
def save(self, *args, **kwargs):
if not os.path.exists(self.image.path) and not self.images_resize():
raise Exception('Error: Thumbnail not created')
super(ShareImage, self).save(*args, **kwargs)
def images_resize(self):
size = (288, 162)
image = Image.open(self.image)
image.thumbnail(size, Image.ANTIALIAS)
name, extension = os.path.splitext(self.image.name)
# to prevent django from creating new folders incorrectly
name = os.path.basename(name)
extension = extension.lower()
file_name = name + '_thumbnail' + extension
if extension in ['.jpg', '.jpeg']:
file_extension = 'JPEG'
elif extension == '.png':
file_extension = 'PNG'
elif extension == '.gif':
file_extension = 'GIF'
else:
raise Exception('Error: Files extension not supported')
temp = BytesIO()
image.save(temp, file_extension)
temp.seek(0)
if not os.path.exists(self.image.path):
self.thumbnail.save(
file_name, ContentFile(temp.read()), save=False
)
return True
@receiver(models.signals.post_delete, sender=ShareImage)
def auto_delete_images_on_delete(instance, **kwargs):
if instance.image:
if os.path.isfile(instance.image.path):
os.remove(instance.image.path)
if instance.thumbnail:
if os.path.isfile(instance.thumbnail.path):
os.remove(instance.thumbnail.path)
@receiver(models.signals.pre_save, sender=ShareImage)
def auto_delete_images_on_change(instance, **kwargs):
if not instance.pk:
return False
try:
old_image = ShareImage.objects.get(pk=instance.pk).image
old_thumb = ShareImage.objects.get(pk=instance.pk).thumbnail
except ShareImage.DoesNotExist:
return False
new_image = instance.image
new_thumb = instance.thumbnail
if old_image != new_image:
if os.path.isfile(old_image.path):
os.remove(old_image.path)
if old_thumb != new_thumb:
if os.path.isfile(old_thumb.path):
os.remove(old_thumb.path)
示例app2:
import os
from io import BytesIO
from PIL import Image
from django.db import models
from django.dispatch import receiver
from django.core.files.base import ContentFile
from .storage import OverwriteStorage
class Logo(models.Model):
title = models.CharField(max_length=100, unique=True, verbose_name='Titel')
slug = models.SlugField(max_length=100, unique=True)
created = models.DateTimeField(auto_now_add=True, verbose_name='Erstellt')
updated = models.DateTimeField(auto_now=True, verbose_name='Aktualisiert')
image = models.ImageField(upload_to='website/header/images/',
verbose_name='Bild', storage=OverwriteStorage())
thumbnail = models.ImageField(upload_to='website/header/images/',
editable=False, storage=OverwriteStorage())
public = models.BooleanField(verbose_name='Öffentlich')
class Meta:
ordering = ['-updated']
verbose_name = 'Logo'
verbose_name_plural = 'Logos'
def __str__(self):
return self.title
您可以使ShareImage
成為抽象模型 ,並從中ShareImage
其他類。 例如:
class ShareImage(models.Model):
...
class Meta:
abstract = True
class Logo(ShareImage):
...
這樣, Logo
類將具有image
和thumbnail
字段。 但這不會觸發信號。
另外,還有另一種方法可以將ShareImage
作為OneToOneField添加到Logo
:
class Logo(models.Model):
image = models.OneToOneField(ShareImage)
...
def delete(self, *args, **kwargs):
self.image.delete()
return super(Logo, self).delete(*args, **kwargs)
這樣, ShareImage
刪除應該觸發那些信號。
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