planetstack/core/models/plcorebase.py

   1 import os
   2 import sys
   3 from django.db import models
   4 from django.forms.models import model_to_dict
   5 from django.core.urlresolvers import reverse
   6 from django.forms.models import model_to_dict
   7 from django.utils import timezone
   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         parent=super(PlCoreBaseDeletionManager, self)
  27         if hasattr(parent, "get_queryset"):
  28             return parent.get_queryset().filter(deleted=True)
  29         else:
  30             return parent.get_query_set().filter(deleted=True)
  31
  32     # deprecated in django 1.7 in favor of get_queryset().
  33     def get_query_set(self):
  34         return self.get_queryset()
  35
  36 # This manager will be inherited by all subclasses because
  37 # the core model is abstract.
  38 class PlCoreBaseManager(models.Manager):
  39     def get_queryset(self):
  40         parent=super(PlCoreBaseManager, self)
  41         if hasattr(parent, "get_queryset"):
  42             return parent.get_queryset().filter(deleted=False)
  43         else:
  44             return parent.get_query_set().filter(deleted=False)
  45
  46     # deprecated in django 1.7 in favor of get_queryset().
  47     def get_query_set(self):
  48         return self.get_queryset()
  49
  50 class PlCoreBase(models.Model):
  51     objects = PlCoreBaseManager()
  52     deleted_objects = PlCoreBaseDeletionManager()
  53
  54     # default values for created and updated are only there to keep evolution
  55     # from failing.
  56     created = models.DateTimeField(auto_now_add=True, default=timezone.now)
  57     updated = models.DateTimeField(auto_now=True, default=timezone.now)
  58     enacted = models.DateTimeField(null=True, default=None)
  59     backend_status = models.CharField(max_length=140,
  60                                       default="Provisioning in progress")
  61     deleted = models.BooleanField(default=False)
  62
  63     class Meta:
  64         # Changing abstract to False would require the managers of subclasses of
  65         # PlCoreBase to be customized individually.
  66         abstract = True
  67         app_label = "core"
  68
  69     def __init__(self, *args, **kwargs):
  70         super(PlCoreBase, self).__init__(*args, **kwargs)
  71         self.__initial = self._dict
  72         self.silent = False
  73
  74     @property
  75     def diff(self):
  76         d1 = self.__initial
  77         d2 = self._dict
  78         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  79         return dict(diffs)
  80
  81     @property
  82     def has_changed(self):
  83         return bool(self.diff)
  84
  85     @property
  86     def changed_fields(self):
  87         return self.diff.keys()
  88
  89     def get_field_diff(self, field_name):
  90         return self.diff.get(field_name, None)
  91
  92     def can_update(self, user):
  93         if user.is_readonly:
  94             return False
  95         if user.is_admin:
  96             return True
  97         return False
  98
  99     def delete(self, *args, **kwds):
 100         # so we have something to give the observer
 101         purge = kwds.get('purge',False)
 102         silent = kwds.get('silent',False)
 103         try:
 104             purge = purge or observer_disabled
 105         except NameError:
 106             pass
 107
 108         if (purge):
 109             del kwds['purge']
 110             super(PlCoreBase, self).delete(*args, **kwds)
 111         else:
 112             self.deleted = True
 113             self.enacted=None
 114             self.save(update_fields=['enacted','deleted'], silent=silent)
 115
 116     def save(self, *args, **kwargs):
 117         # let the user specify silence as either a kwarg or an instance varible
 118         silent = self.silent
 119         if "silent" in kwargs:
 120             silent=silent or kwargs.pop("silent")
 121
 122         super(PlCoreBase, self).save(*args, **kwargs)
 123
 124         # This is a no-op if observer_disabled is set
 125         if not silent:
 126             notify_observer()
 127
 128         self.__initial = self._dict
 129
 130     def save_by_user(self, user, *args, **kwds):
 131         if self.can_update(user):
 132             self.save(*args, **kwds)
 133
 134     def delete_by_user(self, user, *args, **kwds):
 135         if self.can_update(user):
 136             self.delete(*args, **kwds)
 137
 138     @property
 139     def _dict(self):
 140         return model_to_dict(self, fields=[field.name for field in
 141                              self._meta.fields])
 142
 143
 144