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 PlCoreBaseDeletionManager(models.Manager):
  24     def get_query_set(self):
  25         return super(PlCoreBaseDeletedManager, self).get_query_set().filter(deleted=True)
  26
  27 # This manager will be inherited by all subclasses because
  28 # the core model is abstract.
  29 class PlCoreBaseManager(models.Manager):
  30     def get_query_set(self):
  31         return super(PlCoreBaseManager, self).get_query_set().filter(deleted=False)
  32
  33
  34 class PlCoreBase(models.Model):
  35     objects = PlCoreBaseManager()
  36     deleted_objects = PlCoreBaseDeletionManager()
  37     created = models.DateTimeField(auto_now_add=True)
  38     updated = models.DateTimeField(auto_now=True)
  39     # default values for created and updated are only there to keep evolution
  40     # from failing.
  41
  42     created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now())
  43     updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now())
  44     enacted = models.DateTimeField(null=True, default=None)
  45     backend_status = models.CharField(max_length=140,
  46                                       default="Provisioning in progress")
  47     deleted = models.BooleanField(default=False)
  48
  49     class Meta:
  50         # Changing abstract to False would require the managers of subclasses of
  51         # PlCoreBase to be customized individually.
  52         abstract = True
  53         app_label = "core"
  54
  55     def __init__(self, *args, **kwargs):
  56         super(PlCoreBase, self).__init__(*args, **kwargs)
  57         self.__initial = self._dict
  58
  59     @property
  60     def diff(self):
  61         d1 = self.__initial
  62         d2 = self._dict
  63         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  64         return dict(diffs)
  65
  66     @property
  67     def has_changed(self):
  68         return bool(self.diff)
  69
  70     @property
  71     def changed_fields(self):
  72         return self.diff.keys()
  73
  74     def get_field_diff(self, field_name):
  75         return self.diff.get(field_name, None)
  76
  77     def can_update(self, user):
  78         if user.is_readonly:
  79             return False
  80         if user.is_admin:
  81             return True
  82         return False
  83
  84     def delete(self, *args, **kwds):
  85         # so we have something to give the observer
  86         purge = kwds.get('purge',True)
  87         if (observer_disabled or purge):
  88             super(PlCoreBase, self).delete(*args, **kwargs)
  89         else:
  90             self.deleted = True
  91             self.enacted=None
  92             self.save(update_fields=['enacted','deleted'])
  93
  94
  95     def save(self, *args, **kwargs):
  96         super(PlCoreBase, self).save(*args, **kwargs)
  97
  98         # This is a no-op if observer_disabled is set
  99         notify_observer()
 100
 101         self.__initial = self._dict
 102
 103     def save_by_user(self, user, *args, **kwds):
 104         if self.can_update(user):
 105             self.save(*args, **kwds)
 106
 107     def delete_by_user(self, user, *args, **kwds):
 108         if self.can_update(user):
 109             self.delete(*args, **kwds)
 110
 111     @property
 112     def _dict(self):
 113         return model_to_dict(self, fields=[field.name for field in
 114                              self._meta.fields])
 115
 116
 117