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author | SVN-Git Migration <python-modules-team@lists.alioth.debian.org> | 2015-10-08 11:51:45 -0700 |
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committer | SVN-Git Migration <python-modules-team@lists.alioth.debian.org> | 2015-10-08 11:51:45 -0700 |
commit | 2228968f3d51a3d686adb2839bf43e018432f941 (patch) | |
tree | 9e95992c4b09bbea50336e91a709a775a20fd1e5 /tagging/fields.py | |
download | python-django-tagging-2228968f3d51a3d686adb2839bf43e018432f941.tar python-django-tagging-2228968f3d51a3d686adb2839bf43e018432f941.tar.gz |
Imported Upstream version 0.1+svn102upstream/0.1+svn102
Diffstat (limited to 'tagging/fields.py')
-rw-r--r-- | tagging/fields.py | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/tagging/fields.py b/tagging/fields.py new file mode 100644 index 0000000..1e66458 --- /dev/null +++ b/tagging/fields.py @@ -0,0 +1,109 @@ +from django.db.models import signals +from django.db.models.fields import CharField +from django.dispatch import dispatcher + +from tagging import settings +from tagging.models import Tag +from tagging.validators import isTagList + +class TagField(CharField): + """ + A "special" character field that actually works as a relationship to tags + "under the hood". This exposes a space-separated string of tags, but does + the splitting/reordering/etc. under the hood. + """ + def __init__(self, **kwargs): + kwargs['max_length'] = kwargs.get('max_length', 255) + kwargs['blank'] = kwargs.get('blank', True) + kwargs['validator_list'] = [isTagList] + kwargs.get('validator_list', []) + super(TagField, self).__init__(**kwargs) + + def contribute_to_class(self, cls, name): + super(TagField, self).contribute_to_class(cls, name) + + # Make this object the descriptor for field access. + setattr(cls, self.name, self) + + # Save tags back to the database post-save + dispatcher.connect(self._save, signal=signals.post_save, sender=cls) + + def __get__(self, instance, owner=None): + """ + Tag getter. Returns an instance's tags if accessed on an instance, and + all of a model's tags if called on a class. That is, this model:: + + class Link(models.Model): + ... + tags = TagField() + + Lets you do both of these:: + + >>> l = Link.objects.get(...) + >>> l.tags + 'tag1 tag2 tag3' + + >>> Link.tags + 'tag1 tag2 tag3 tag4' + + """ + # Handle access on the model (i.e. Link.tags) + if instance is None: + return tags2str(Tag.objects.usage_for_model(owner)) + + tags = self._get_instance_tag_cache(instance) + if tags is None: + if instance._get_pk_val() is None: + self._set_instance_tag_cache(instance, '') + else: + self._set_instance_tag_cache(instance, tags2str(Tag.objects.get_for_object(instance))) + return self._get_instance_tag_cache(instance) + + def __set__(self, instance, value): + """ + Set an object's tags. + """ + if instance is None: + raise AttributeError('%s can only be set on instances.' % self.name) + if settings.FORCE_LOWERCASE_TAGS and value is not None: + self._set_instance_tag_cache(instance, value.lower()) + else: + self._set_instance_tag_cache(instance, value) + + def _save(self, signal, sender, instance): + """ + Save tags back to the database + """ + tags = self._get_instance_tag_cache(instance) + if tags is not None : + Tag.objects.update_tags(instance, tags) + + def __delete__(self, instance): + """ + Clear all of an object's tags. + """ + self._set_instance_tag_cache(instance, '') + + def _get_instance_tag_cache(self, instance): + """ + Helper: get an instance's tag cache. + """ + return getattr(instance, '_%s_cache' % self.attname, None) + + def _set_instance_tag_cache(self, instance, tags): + """ + Helper: set an instance's tag cache. + """ + setattr(instance, '_%s_cache' % self.attname, tags) + + def get_internal_type(self): + return 'CharField' + + def formfield(self, **kwargs): + from tagging import forms + defaults = {'form_class': forms.TagField} + defaults.update(kwargs) + return super(TagField, self).formfield(**defaults) + +# Helper +def tags2str(tagset): + return u' '.join([t.name for t in tagset]) |