| 1 | from django.db import models |
|---|
| 2 | from django.db.models import signals |
|---|
| 3 | from django.dispatch import dispatcher |
|---|
| 4 | |
|---|
| 5 | class Category(models.Model): |
|---|
| 6 | name = models.CharField(maxlength=32) |
|---|
| 7 | post_count = models.IntegerField(blank=True, default=0) |
|---|
| 8 | |
|---|
| 9 | def __unicode__(self): |
|---|
| 10 | return u"<Category %s '%s' (%s)>" % (self.id, self.name, self.post_count) |
|---|
| 11 | |
|---|
| 12 | def __repr__(self): |
|---|
| 13 | return self.__unicode__() |
|---|
| 14 | |
|---|
| 15 | def _m2m_entry(self, entry, increment): |
|---|
| 16 | if not isinstance(entry, Entry): |
|---|
| 17 | entry = Entry.objects.get(pk=entry) |
|---|
| 18 | if entry.status == 'P' and (self.post_count or increment): |
|---|
| 19 | self.post_count += increment |
|---|
| 20 | self.save() |
|---|
| 21 | |
|---|
| 22 | @staticmethod |
|---|
| 23 | def m2m_entry(signal, sender, instance, objs=None): |
|---|
| 24 | if sender == Entry: |
|---|
| 25 | # instance ---> Category, objs ---> Entry |
|---|
| 26 | if signal == signals.m2m_clear_items: |
|---|
| 27 | instance.post_count = 0 |
|---|
| 28 | instance.save() |
|---|
| 29 | return |
|---|
| 30 | increment = 1 |
|---|
| 31 | if signal == signals.m2m_remove_items: |
|---|
| 32 | increment = -1 |
|---|
| 33 | for obj in objs: |
|---|
| 34 | instance._m2m_entry(obj, increment) |
|---|
| 35 | else: |
|---|
| 36 | # instance ---> Entry, objs ---> Category |
|---|
| 37 | increment = -1 |
|---|
| 38 | if signal == signals.m2m_add_items: |
|---|
| 39 | increment = 1 |
|---|
| 40 | elif signal == signals.m2m_clear_items: |
|---|
| 41 | objs = list(instance.categories.all()) |
|---|
| 42 | for obj in objs: |
|---|
| 43 | if not isinstance(obj, Category): |
|---|
| 44 | obj = Category.objects.get(pk=obj) |
|---|
| 45 | obj._m2m_entry(instance, increment) |
|---|
| 46 | |
|---|
| 47 | |
|---|
| 48 | class Entry(models.Model): |
|---|
| 49 | |
|---|
| 50 | title = models.CharField(maxlength=64) |
|---|
| 51 | status = models.CharField(maxlength=1, blank=True, choices=(('P', 'Published'), ('D', 'Draft')), default='D') |
|---|
| 52 | categories = models.ManyToManyField(Category, blank=True, null=True) |
|---|
| 53 | |
|---|
| 54 | def __init__(self, *args, **kw): |
|---|
| 55 | super(Entry, self).__init__(*args, **kw) |
|---|
| 56 | self._status = self.status |
|---|
| 57 | |
|---|
| 58 | def __unicode__(self): |
|---|
| 59 | return u"<Post '%s'>" % self.title |
|---|
| 60 | |
|---|
| 61 | def __repr__(self): |
|---|
| 62 | return self.__unicode__() |
|---|
| 63 | |
|---|
| 64 | def save(self): |
|---|
| 65 | super(Entry, self).save() |
|---|
| 66 | if self.status == 'P' and self._status != 'P': |
|---|
| 67 | Category.m2m_entry(signals.m2m_add_items, Category, self, list(self.categories.all())) |
|---|
| 68 | elif self.status != 'P' and self._status == 'P': |
|---|
| 69 | Category.m2m_entry(signals.m2m_remove_items, Category, self, list(self.categories.all())) |
|---|
| 70 | |
|---|
| 71 | |
|---|
| 72 | # TODO: do not use sender |
|---|
| 73 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_add_items, sender=Category) |
|---|
| 74 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_remove_items, sender=Category) |
|---|
| 75 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_clear_items, sender=Category) |
|---|
| 76 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_add_items, sender=Entry) |
|---|
| 77 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_remove_items, sender=Entry) |
|---|
| 78 | dispatcher.connect(Category.m2m_entry, signal=signals.m2m_clear_items, sender=Entry) |
|---|
