old_contents: # -*- coding: utf-8 -*-
  from datetime import datetime
  
  from django.db import models
  from django.utils.translation import gettext_lazy as _
  from django.utils.encoding import python_2_unicode_compatible
  
  
  @python_2_unicode_compatible
  class ACL(models.Model):
      acl_list = {}
      resource = models.CharField(
          _("Resource name"),
          max_length=255,
          db_index=True,
      )
      display = models.CharField(
          _("displayed name"),
          max_length=255,
          null=True,
          blank=True,
      )
      created_at = models.DateTimeField(
          _("Creation time"),
          default=datetime.now(),
      )
      is_available = models.BooleanField(
          _("Is available to assign"),
          default=True,
      )
  
      class Meta:
          app_label = 'yaacl'
  
      def __str__(self):
          if self.display:
              return "%s (%s)" % (self.display, self.resource)
          else:
              return self.resource
  
new_contents: # -*- coding: utf-8 -*-
  from datetime import datetime
  
  from django.db import models
  from django.utils.translation import gettext_lazy as _
  from django.utils.encoding import python_2_unicode_compatible
  
  
  @python_2_unicode_compatible
  class ACL(models.Model):
      acl_list = {}
      resource = models.CharField(
          _("Resource name"),
          max_length=255,
          db_index=True,
      )
      display = models.CharField(
          _("displayed name"),
          max_length=255,
          null=True,
          blank=True,
      )
      created_at = models.DateTimeField(
          _("Creation time"),
          auto_now_add=True,
      )
      is_available = models.BooleanField(
          _("Is available to assign"),
          default=True,
      )
  
      class Meta:
          app_label = 'yaacl'
  
      def __str__(self):
          if self.display:
              return "%s (%s)" % (self.display, self.resource)
          else:
              return self.resource
  
subject: Use `auto_now_add` to make ACL.created_at timezone aware