http://chriskief.com/2012/12/17/symfony2-vs-django-models/

blog.py

from django.db import models


class BlogManager(models.Manager):

    def get_tags(self):

        # get just the tags
        tags = self.values('tags')

        # combine all tags into a single list
        all_tags = []
        for tag in tags:
            all_tags += tag.values()[0].split(',')

        # strip whitespace
        stripped_tags = [tag.strip() for tag in all_tags]
        return stripped_tags


class Blog(models.Model):

    title = models.CharField(max_length=255)
    slug = models.CharField(max_length=255)
    author = models.CharField(max_length=100)
    blog = models.TextField()
    image = models.CharField(max_length=20)
    tags = models.TextField()
    created = models.DateTimeField('date created', auto_now_add=True)
    updated = models.DateTimeField('last updated', auto_now_add=True, auto_now=True)
    objects = BlogManager()

    def __unicode__(self):
        return self.title

    class Meta:
        app_label = 'app'