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