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 class PlCoreBase(models.Model):
  22
  23     # default values for created and updated are only there to keep evolution
  24     # from failing.
  25
  26     created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now())
  27     updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now())
  28     enacted = models.DateTimeField(null=True, default=None)
  29     backend_status = models.CharField(max_length=140,
  30                                       default="Ok")
  31
  32     class Meta:
  33         abstract = True
  34         app_label = "core"
  35
  36     def __init__(self, *args, **kwargs):
  37         super(PlCoreBase, self).__init__(*args, **kwargs)
  38         self.__initial = self._dict
  39
  40     @property
  41     def diff(self):
  42         d1 = self.__initial
  43         d2 = self._dict
  44         diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
  45         return dict(diffs)
  46
  47     @property
  48     def has_changed(self):
  49         return bool(self.diff)
  50
  51     @property
  52     def changed_fields(self):
  53         return self.diff.keys()
  54
  55     def get_field_diff(self, field_name):
  56         return self.diff.get(field_name, None)
  57
  58     def can_update(self, user):
  59         if user.is_readonly:
  60             return False
  61         if user.is_admin:
  62             return True
  63         return False
  64
  65     def delete(self, *args, **kwds):
  66         # so we have something to give the observer
  67         pk = self.pk
  68         model_dict = model_to_dict(self)
  69         for (k,v) in model_dict.items():
  70             # things like datetime are not JSON serializable
  71             model_dict[k] = str(v)
  72
  73         super(PlCoreBase, self).delete(*args, **kwds)
  74
  75         # This is a no-op if observer_disabled is set
  76         notify_observer(model=self, delete=True, pk=pk, model_dict=model_dict)
  77
  78     def save(self, *args, **kwargs):
  79         super(PlCoreBase, self).save(*args, **kwargs)
  80
  81         # This is a no-op if observer_disabled is set
  82         notify_observer()
  83
  84         self.__initial = self._dict
  85
  86     def save_by_user(self, user, *args, **kwds):
  87         if self.can_update(user):
  88             self.save(*args, **kwds)
  89
  90     def delete_by_user(self, user, *args, **kwds):
  91         if self.can_update(user):
  92             self.delete(*args, **kwds)
  93
  94     @property
  95     def _dict(self):
  96         return model_to_dict(self, fields=[field.name for field in
  97                              self._meta.fields])
  98
  99
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