homelog/container/models.py

from django.db import models
from django.conf import settings
from django.contrib.auth import get_user_model

def get_sentinel_user():
    return get_user_model().objects.get_or_create(username='deleted')[0]

class ContainerType(models.Model):
    named_id = models.CharField(max_length=40, unique=True)
    description = models.CharField(max_length=200)
    width = models.IntegerField('width in mm')
    height = models.IntegerField('height in mm')
    length = models.IntegerField('length in mm')
    inner_width = models.IntegerField('inner width in mm', blank=True, null=True)
    inner_height = models.IntegerField('inner height in mm', blank=True, null=True)
    inner_length = models.IntegerField('inner length in mm', blank=True, null=True)
    has_cover = models.BooleanField('container has a cover')
    contains_container = models.BooleanField('container can bear container')
    created_ts = models.DateTimeField('datetime created', auto_now_add=True)
    created_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET(get_sentinel_user), related_name='created_container_types')
    changed_ts = models.DateTimeField('datetime updated', auto_now=True)
    changed_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET(get_sentinel_user), related_name='changed_container_types')

class Container(models.Model):
    named_id = models.CharField(max_length=40)
    container_type = models.ForeignKey(ContainerType, on_delete=models.CASCADE)
    color = models.CharField(max_length=60, blank=True)
    description = models.CharField(max_length=200, blank=True)
    created_ts = models.DateTimeField('datetime created', auto_now_add=True)
    created_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET(get_sentinel_user), related_name='created_container')
    changed_ts = models.DateTimeField('datetime updated', auto_now=True)
    changed_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.SET(get_sentinel_user), related_name='changed_container')