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     # default values for created and updated are only there to keep evolution
  28     # from failing.
  29 class PlCoreBase(models.Model):
  30     objects = PlCoreBaseManager()
  31     created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now())
  32     updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now())
  33     enacted = models.DateTimeField(null=True, default=None)
  34     backend_status = models.CharField(max_length=140,
  35                                       default="Provisioning in progress")
  36     deleted = models.BooleanField(default=False)
  37
  38     class Meta:
  39         # Changing abstract to False would require the managers of subclasses of
  40         # PlCoreBase to be customized individually.
  41         abstract = True
  42         app_label = "core"
  43
  44     def __init__(self, *args, **kwargs):
  45         super(PlCoreBase, self).__init__(*args, **kwargs)
  46         self.__initial = self._dict
  47
  48     @property
  49     def diff(self):
  50         d1 = self.__initial
  51         d2 = self._dict
  52         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  53         return dict(diffs)
  54
  55     @property
  56     def has_changed(self):
  57         return bool(self.diff)
  58
  59     @property
  60     def changed_fields(self):
  61         return self.diff.keys()
  62
  63     def get_field_diff(self, field_name):
  64         return self.diff.get(field_name, None)
  65
  66     def can_update(self, user):
  67         if user.is_readonly:
  68             return False
  69         if user.is_admin:
  70             return True
  71         return False
  72
  73     def delete(self, *args, **kwds):
  74         # so we have something to give the observer
  75         purge = kwds.get('purge',True)
  76         if (observer_disabled or purge):
  77             super(PlCoreBase, self).delete(*args, **kwargs)
  78         else:
  79             self.deleted = True
  80             self.enacted=None
  81             self.save(update_fields=['enacted','deleted'])
  82
  83
  84     def save(self, *args, **kwargs):
  85         super(PlCoreBase, self).save(*args, **kwargs)
  86
  87         # This is a no-op if observer_disabled is set
  88         notify_observer()
  89
  90         self.__initial = self._dict
  91
  92     def save_by_user(self, user, *args, **kwds):
  93         if self.can_update(user):
  94             self.save(*args, **kwds)
  95
  96     def delete_by_user(self, user, *args, **kwds):
  97         if self.can_update(user):
  98             self.delete(*args, **kwds)
  99
 100     @property
 101     def _dict(self):
 102         return model_to_dict(self, fields=[field.name for field in
 103                              self._meta.fields])
 104
 105
 106