Class attribute inheritance in Django models

Question

There are two models:

class BaseImage(models.Model):
    description = models.CharField(max_length=200)
    image = models.ImageField(upload_to='images')

    class Meta:
        abstract = True

class PostImage(BaseImage):
    in_text = models.BooleanField()

    def __init__(self, *args, **kwargs):
        super(BaseImage, self).__init__(*args, **kwargs)
        self.image.upload_to = 'images/news/%Y/%m/%d'

How can I set upload_to property in the base model? This my attempt doesn't work:

        self.image.upload_to = 'images/news/%Y/%m/%d'

Here is a useful variation: stackoverflow.com/questions/3669830/… — Damaged Organic
– Damaged Organic, Commented Dec 26, 2016 at 14:27

Rohan · Accepted Answer · 2012-09-11 08:15:15Z

8

What I can suggest is to write function to get upload to method from instance e.g.

in models.py

#default method to get file upload path
def get_upload_to(instance, filename):
    return instance.get_upload_to_path(filename)

class BaseImage(models.Model):
    description = models.CharField(max_length=200)
    image = models.ImageField(upload_to=get_upload_to)

    class Meta:
        abstract = True
    #method on the class to provide upload path for files specific to these objects
    def get_upload_to_path(instance, filename):
         return 'images/'+filename

class PostImage(BaseImage):
    in_text = models.BooleanField()

    #method to provide upload path for PostImage objects
    def get_upload_to_path(instance, filename):
    #change date.year etc to appropriate variables
         return 'images/news/%Y/%m/%d' % (date.year, date.month, date.day)

edited Sep 11, 2012 at 8:15

answered Sep 10, 2012 at 9:24

Rohan

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3 Comments

art.zhitnik Over a year ago

I understand the idea, but your code is not clear enough. Please, make corrections for other people.

Rohan Over a year ago

@art.zhitnik Added some comments, do they help?

art.zhitnik Over a year ago

If I understood right, instead of upload_to='images' must be upload_to=get_upload_to, and class methods must be named as get_upload_to_path, not get_upload_to.

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