planetstack/core/models/plcorebase.py

   1 import os
   2 from django.db import models
   3 from django.forms.models import model_to_dict
   4 from django.core.urlresolvers import reverse
   5 from django.forms.models import model_to_dict
   6
   7 try:
   8     # This is a no-op if observer_disabled is set to 1 in the config file
   9     from observer import *
  10 except:
  11     print "import of observer failed! printing traceback and disabling observer:"
  12     import traceback
  13     traceback.print_exc()
  14
  15     # guard against something failing
  16     def notify_observer():
  17         pass
  18
  19 # This manager will be inherited by all subclasses because
  20 # the core model is abstract.
  21 class PlCoreBaseManager(models.Manager):
  22     def get_query_set(self):
  23         return super(PlCoreBaseManager, self).get_query_set().filter(deleted=False)
  24
  25 class PlCoreBase(models.Model):
  26     objects = PlCoreBaseManager()
  27     created = models.DateTimeField(auto_now_add=True)
  28     updated = models.DateTimeField(auto_now=True)
  29     enacted = models.DateTimeField(null=True, default=None)
  30     backend_status = models.CharField(max_length=140,
  31                                       default="Provisioning in progress")
  32     deleted = models.BooleanField(default=False)
  33
  34     class Meta:
  35         # Changing abstract to False would require the managers of subclasses of
  36         # PlCoreBase to be customized individually.
  37         abstract = True
  38         app_label = "core"
  39
  40     def __init__(self, *args, **kwargs):
  41         super(PlCoreBase, self).__init__(*args, **kwargs)
  42         self.__initial = self._dict
  43
  44     @property
  45     def diff(self):
  46         d1 = self.__initial
  47         d2 = self._dict
  48         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  49         return dict(diffs)
  50
  51     @property
  52     def has_changed(self):
  53         return bool(self.diff)
  54
  55     @property
  56     def changed_fields(self):
  57         return self.diff.keys()
  58
  59     def get_field_diff(self, field_name):
  60         return self.diff.get(field_name, None)
  61
  62     def can_update(self, user):
  63         if user.is_readonly:
  64             return False
  65         if user.is_admin:
  66             return True
  67         return False
  68
  69     def delete(self, *args, **kwds):
  70         # so we have something to give the observer
  71         purge = kwds.get('purge',True)
  72         if (observer_disabled or purge):
  73             super(PlCoreBase, self).delete(*args, **kwargs)
  74         else:
  75             self.deleted = True
  76             self.enacted=None
  77             self.save(update_fields=['enacted','deleted'])
  78
  79
  80     def save(self, *args, **kwargs):
  81         super(PlCoreBase, self).save(*args, **kwargs)
  82
  83         # This is a no-op if observer_disabled is set
  84         notify_observer()
  85
  86         self.__initial = self._dict
  87
  88     def save_by_user(self, user, *args, **kwds):
  89         if self.can_update(user):
  90             self.save(*args, **kwds)
  91
  92     def delete_by_user(self, user, *args, **kwds):
  93         if self.can_update(user):
  94             self.delete(*args, **kwds)
  95
  96     @property
  97     def _dict(self):
  98         return model_to_dict(self, fields=[field.name for field in
  99                              self._meta.fields])
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