phoikoi · June 21, 2018 05:21 · Apr 20, 2012
diff --git a/imagewiththumbnails_updateable.py b/imagewiththumbnails_updateable.py
@@ -0,0 +1,80 @@
+# Extension of http://www.yilmazhuseyin.com/blog/dev/create-thumbnails-imagefield-django/
+
+# Note: image_folder and thumbnail_folder are both a callable (ie. a lambda that does a '/'.join())
+
+class Image(Media):
+    image = models.ImageField(
+        upload_to=image_folder
+    )
+
+    thumbnail = models.ImageField(
+        upload_to=thumbnail_folder,
+        max_length=500,
+        null=True,
+        blank=True
+    )
+
+    def create_thumbnail(self):
+        # original code for this method came from
+        # http://snipt.net/danfreak/generate-thumbnails-in-django-with-pil/
+
+        # If there is no image associated with this.
+        # do not create thumbnail
+        if not self.image:
+            return
+
+        from PIL import Image
+        from cStringIO import StringIO
+        from django.core.files.uploadedfile import SimpleUploadedFile
+        import os
+
+        # Set our max thumbnail size in a tuple (max width, max height)
+        THUMBNAIL_SIZE = (99, 66)
+
+        DJANGO_TYPE = self.image.file.content_type
+
+        if DJANGO_TYPE == 'image/jpeg':
+            PIL_TYPE = 'jpeg'
+            FILE_EXTENSION = 'jpg'
+        elif DJANGO_TYPE == 'image/png':
+            PIL_TYPE = 'png'
+            FILE_EXTENSION = 'png'
+
+        # Open original photo which we want to thumbnail using PIL's Image
+        image = Image.open(StringIO(self.image.read()))
+
+        # We use our PIL Image object to create the thumbnail, which already
+        # has a thumbnail() convenience method that contrains proportions.
+        # Additionally, we use Image.ANTIALIAS to make the image look better.
+        # Without antialiasing the image pattern artifacts may result.
+        image.thumbnail(THUMBNAIL_SIZE, Image.ANTIALIAS)
+
+        # Save the thumbnail
+        temp_handle = StringIO()
+        image.save(temp_handle, PIL_TYPE)
+        temp_handle.seek(0)
+
+        # Save image to a SimpleUploadedFile which can be saved into
+        # ImageField
+        suf = SimpleUploadedFile(os.path.split(self.image.name)[-1],
+                temp_handle.read(), content_type=DJANGO_TYPE)
+        # Save SimpleUploadedFile into image field
+        self.thumbnail.save(
+            '%s_thumbnail.%s' % (os.path.splitext(suf.name)[0], FILE_EXTENSION),
+            suf,
+            save=False
+        )
+
+    def save(self, *args, **kwargs):
+
+        self.create_thumbnail()
+
+        force_update = False
+
+        # If the instance already has been saved, it has an id and we set 
+        # force_update to True
+        if self.id:
+            force_update = True
+
+        # Force an UPDATE SQL query if we're editing the image to avoid integrity exception
+        super(Image, self).save(force_update=force_update)
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