Question

I have a base model, and proxy models. I want to change value of upload_to of ‘image’ filed, that depends on ‘file_type’ filed.
I’m not sure how to do this, do I need to specify it in my .Manager class or in Proxy class.
Can you please give me same detail how to do this.

class FileDescription(models.Model):

    class Meta:
        ordering = ['file_creation_time']

    TYPE_CHOICES = (
        ('homework', 'Homework'),
        ('class', 'Class Papers'),
        ('random', 'Random Papers')                    
    )

    subject = models.ForeignKey('Subjects', null=True, blank=True, primary_key=True)
    subject_name = models.CharField(max_length=100, unique=False)
    file_type = models.CharField(max_length=100, choices=TYPE_CHOICES) 
    ....
    ....
    image = models.ImageField(upload_to= ???????????      blank=True, null=True, max_length=255)

    def __unicode__(self):
        return u'%s' % (self.file_name)

class HomeworkManager(models.Manager):
    def get_query_set(self):
        qs = super(HomeworkManager, self).get_query_set().filter(file_type='homework')
        return qs

class ClassPapersManager(models.Manager):
    def get_query_set(self):
        qs = super(HomeworkManager, self).get_query_set().filter(file_type='class')
        return qs

class RandomPapersManager(models.Manager):
    def get_query_set(self):
        qs = super(HomeworkManager, self).get_query_set().filter(file_type='random')
        return qs

class Homework(FileDescription):

    class Meta:
        proxy = True

Answer 1

Don’t worry about replacing upload_to just modify the method to handle different subclasses (use a method for upload_to if you’re not already).

def my_upload_to(instance, filename):
    if instance._meta.module_name == 'homework':
        return '/path/to/homework/files/%s' % filename
    if instance._meta.module_name == 'classpaper':
        return '/path/to/classpaper/files/%s' % filename
    if instance._meta.module_name == 'randompaper':
        return '/path/to/randompaper/files/%s' % filename