django-models

Some thoughts: class Model(model.Model): _image=models.ImageField(upload_to=’folder’) thumb=models.ImageField(upload_to=’folder’) description=models.CharField() def set_image(self, val): self._image = val self._image_changed = True # Or put whole logic in here small = rescale_image(self.image,width=100,height=100) self.image_small=SimpleUploadedFile(name,small_pic) def get_image(self): return self._image image = property(get_image, set_image) # this is not needed if small_image is created at set_image def save(self, *args, **kwargs): if getattr(self, ‘_image_changed’, True): small=rescale_image(self.image,width=100,height=100) … Read more

If you mean to do aggregation you can use the aggregation features of the ORM: from django.db.models import Count result = (Members.objects .values(‘designation’) .annotate(dcount=Count(‘designation’)) .order_by() ) This results in a query similar to SELECT designation, COUNT(designation) AS dcount FROM members GROUP BY designation and the output would be of the form [{‘designation’: ‘Salesman’, ‘dcount’: 2}, … Read more

null=True sets NULL (versus NOT NULL) on the column in your DB. Blank values for Django field types such as DateTimeField or ForeignKey will be stored as NULL in the DB. blank determines whether the field will be required in forms. This includes the admin and your custom forms. If blank=True then the field will … Read more