planetstack/core/models/plcorebase.py

   1 import datetime
   2 import os
   3 import sys
   4 from django.db import models
   5 from django.forms.models import model_to_dict
   6 from django.core.urlresolvers import reverse
   7 from django.forms.models import model_to_dict
   8
   9 try:
  10     # This is a no-op if observer_disabled is set to 1 in the config file
  11     from observer import *
  12 except:
  13     print >> sys.stderr, "import of observer failed! printing traceback and disabling observer:"
  14     import traceback
  15     traceback.print_exc()
  16
  17     # guard against something failing
  18     def notify_observer(*args, **kwargs):
  19         pass
  20
  21 # This manager will be inherited by all subclasses because
  22 # the core model is abstract.
  23 class PlCoreBaseManager(models.Manager):
  24     def get_query_set(self):
  25         return super(PlCoreBaseManager, self).get_query_set().filter(deleted=False)
  26
  27 class PlCoreBase(models.Model):
  28     objects = PlCoreBaseManager()
  29     created = models.DateTimeField(auto_now_add=True)
  30     updated = models.DateTimeField(auto_now=True)
  31     # default values for created and updated are only there to keep evolution
  32     # from failing.
  33
  34     created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now())
  35     updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now())
  36     enacted = models.DateTimeField(null=True, default=None)
  37     backend_status = models.CharField(max_length=140,
  38                                       default="Provisioning in progress")
  39     deleted = models.BooleanField(default=False)
  40
  41     class Meta:
  42         # Changing abstract to False would require the managers of subclasses of
  43         # PlCoreBase to be customized individually.
  44         abstract = True
  45         app_label = "core"
  46
  47     def __init__(self, *args, **kwargs):
  48         super(PlCoreBase, self).__init__(*args, **kwargs)
  49         self.__initial = self._dict
  50
  51     @property
  52     def diff(self):
  53         d1 = self.__initial
  54         d2 = self._dict
  55         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  56         return dict(diffs)
  57
  58     @property
  59     def has_changed(self):
  60         return bool(self.diff)
  61
  62     @property
  63     def changed_fields(self):
  64         return self.diff.keys()
  65
  66     def get_field_diff(self, field_name):
  67         return self.diff.get(field_name, None)
  68
  69     def can_update(self, user):
  70         if user.is_readonly:
  71             return False
  72         if user.is_admin:
  73             return True
  74         return False
  75
  76     def delete(self, *args, **kwds):
  77         # so we have something to give the observer
  78         purge = kwds.get('purge',True)
  79         if (observer_disabled or purge):
  80             super(PlCoreBase, self).delete(*args, **kwargs)
  81         else:
  82             self.deleted = True
  83             self.enacted=None
  84             self.save(update_fields=['enacted','deleted'])
  85
  86
  87     def save(self, *args, **kwargs):
  88         super(PlCoreBase, self).save(*args, **kwargs)
  89
  90         # This is a no-op if observer_disabled is set
  91         notify_observer()
  92
  93         self.__initial = self._dict
  94
  95     def save_by_user(self, user, *args, **kwds):
  96         if self.can_update(user):
  97             self.save(*args, **kwds)
  98
  99     def delete_by_user(self, user, *args, **kwds):
 100         if self.can_update(user):
 101             self.delete(*args, **kwds)
 102
 103     @property
 104     def _dict(self):
 105         return model_to_dict(self, fields=[field.name for field in
 106                              self._meta.fields])
 107
 108
 109