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