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 class PlCoreBase(models.Model):
  20
  21     created = models.DateTimeField(auto_now_add=True)
  22     updated = models.DateTimeField(auto_now=True)
  23     enacted = models.DateTimeField(null=True, default=None)
  24     backend_status = models.CharField(max_length=140,
  25                                       default="Ok")
  26
  27     class Meta:
  28         abstract = True
  29         app_label = "core"
  30
  31     def __init__(self, *args, **kwargs):
  32         super(PlCoreBase, self).__init__(*args, **kwargs)
  33         self.__initial = self._dict
  34
  35     @property
  36     def diff(self):
  37         d1 = self.__initial
  38         d2 = self._dict
  39         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  40         return dict(diffs)
  41
  42     @property
  43     def has_changed(self):
  44         return bool(self.diff)
  45
  46     @property
  47     def changed_fields(self):
  48         return self.diff.keys()
  49
  50     def get_field_diff(self, field_name):
  51         return self.diff.get(field_name, None)
  52
  53     def can_update(self, user):
  54         if user.is_readonly:
  55             return False
  56         if user.is_admin:
  57             return True
  58         return False
  59
  60     def delete(self, *args, **kwds):
  61         # so we have something to give the observer
  62         pk = self.pk
  63         model_dict = model_to_dict(self)
  64         for (k,v) in model_dict.items():
  65             # things like datetime are not JSON serializable
  66             model_dict[k] = str(v)
  67
  68         super(PlCoreBase, self).delete(*args, **kwds)
  69
  70         # This is a no-op if observer_disabled is set
  71         notify_observer(model=self, delete=True, pk=pk, model_dict=model_dict)
  72
  73     def save(self, *args, **kwargs):
  74         super(PlCoreBase, self).save(*args, **kwargs)
  75
  76         # This is a no-op if observer_disabled is set
  77         notify_observer()
  78
  79         self.__initial = self._dict
  80
  81     def save_by_user(self, user, *args, **kwds):
  82         if self.can_update(user):
  83             self.save(*args, **kwds)
  84
  85     def delete_by_user(self, user, *args, **kwds):
  86         if self.can_update(user):
  87             self.delete(*args, **kwds)
  88
  89     @property
  90     def _dict(self):
  91         return model_to_dict(self, fields=[field.name for field in
  92                              self._meta.fields])
  93
  94
  95