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: http://stackoverflow.com/questions/3669830/passing-a-callback-as-upload-to-to-filefield/41332610#41332610 — Damaged Organic, Dec 26 '16 at 14:27

Rohan · Accepted Answer · 2012-09-11T08:15:15.970

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 '12 at 08:15

answered Sep 10 '12 at 09:24

Rohan

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I understand the idea, but your code is not clear enough. Please, make corrections for other people. – art.zhitnik Sep 11 '12 at 00:43
@art.zhitnik Added some comments, do they help? – Rohan Sep 11 '12 at 04:01
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. – art.zhitnik Sep 11 '12 at 07:24

Class attribute inheritance in Django models

1 Answers1