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 import model_policy
   9
  10 try:
  11     # This is a no-op if observer_disabled is set to 1 in the config file
  12     from observer import *
  13 except:
  14     print >> sys.stderr, "import of observer failed! printing traceback and disabling observer:"
  15     import traceback
  16     traceback.print_exc()
  17
  18     # guard against something failing
  19     def notify_observer(*args, **kwargs):
  20         pass
  21
  22 # This manager will be inherited by all subclasses because
  23 # the core model is abstract.
  24 class PlCoreBaseDeletionManager(models.Manager):
  25     def get_queryset(self):
  26         return super(PlCoreBaseDeletionManager, self).get_query_set().filter(deleted=True)
  27
  28     # deprecated in django 1.7 in favor of get_queryset()
  29     def get_query_set(self):
  30         return self.get_queryset()
  31
  32 # This manager will be inherited by all subclasses because
  33 # the core model is abstract.
  34 class PlCoreBaseManager(models.Manager):
  35     def get_queryset(self):
  36         return super(PlCoreBaseManager, self).get_query_set().filter(deleted=False)
  37
  38     # deprecated in django 1.7 in favor of get_queryset()
  39     def get_query_set(self):
  40         return self.get_queryset()
  41
  42 class PlCoreBase(models.Model):
  43     objects = PlCoreBaseManager()
  44     deleted_objects = PlCoreBaseDeletionManager()
  45
  46     # default values for created and updated are only there to keep evolution
  47     # from failing.
  48     created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now)
  49     updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now)
  50     enacted = models.DateTimeField(null=True, default=None)
  51     backend_status = models.CharField(max_length=140,
  52                                       default="Provisioning in progress")
  53     deleted = models.BooleanField(default=False)
  54
  55     class Meta:
  56         # Changing abstract to False would require the managers of subclasses of
  57         # PlCoreBase to be customized individually.
  58         abstract = True
  59         app_label = "core"
  60
  61     def __init__(self, *args, **kwargs):
  62         super(PlCoreBase, self).__init__(*args, **kwargs)
  63         self.__initial = self._dict
  64
  65     @property
  66     def diff(self):
  67         d1 = self.__initial
  68         d2 = self._dict
  69         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  70         return dict(diffs)
  71
  72     @property
  73     def has_changed(self):
  74         return bool(self.diff)
  75
  76     @property
  77     def changed_fields(self):
  78         return self.diff.keys()
  79
  80     def get_field_diff(self, field_name):
  81         return self.diff.get(field_name, None)
  82
  83     def can_update(self, user):
  84         if user.is_readonly:
  85             return False
  86         if user.is_admin:
  87             return True
  88         return False
  89
  90     def delete(self, *args, **kwds):
  91         # so we have something to give the observer
  92         purge = kwds.get('purge',False)
  93         try:
  94             purge = purge or observer_disabled
  95         except NameError:
  96             pass
  97
  98         if (purge):
  99             del kwds['purge']
 100             super(PlCoreBase, self).delete(*args, **kwds)
 101         else:
 102             self.deleted = True
 103             self.enacted=None
 104             self.save(update_fields=['enacted','deleted'])
 105
 106
 107     def save(self, *args, **kwargs):
 108         super(PlCoreBase, self).save(*args, **kwargs)
 109
 110         # This is a no-op if observer_disabled is set
 111         notify_observer()
 112
 113         self.__initial = self._dict
 114
 115     def save_by_user(self, user, *args, **kwds):
 116         if self.can_update(user):
 117             self.save(*args, **kwds)
 118
 119     def delete_by_user(self, user, *args, **kwds):
 120         if self.can_update(user):
 121             self.delete(*args, **kwds)
 122
 123     @property
 124     def _dict(self):
 125         return model_to_dict(self, fields=[field.name for field in
 126                              self._meta.fields])
 127
 128
 129