blob: 5af0a509eb4a73e4a3216c98609bbafa731033e1 [file] [log] [blame]
from google.appengine.ext import db
import string
import soc.models.linkable
class Tag(db.Model):
"""Google AppEngine model for store of tags.
tag = db.StringProperty(required=True)
"The actual string value of the tag."
added = db.DateTimeProperty(auto_now_add=True)
"The date and time that the tag was first added to the datastore."
tagged = db.ListProperty(db.Key)
"A List of db.Key values for the datastore objects that have been tagged with this tag value."
tagged_count = db.IntegerProperty(default=0)
"The number of entities in tagged."
auto_delete = db.BooleanProperty(required=True, default=False)
"If true, a tag instance should be deleted when tagged_count reaches zero."
scope = db.ReferenceProperty(reference_class=soc.models.linkable.Linkable,
"Each tag is scoped under some linkable model."
def _key_name(cls, scope_path, tag_name):
"""Create the key_name from program key_name as scope_path and tag_name.
return scope_path + '/' + tag_name
def remove_tagged(self, key):
def remove_tagged_txn():
if key in self.tagged:
self.tagged_count -= 1
if not self.tagged_count and self.auto_delete:
def add_tagged(self, key):
def add_tagged_txn():
if key not in self.tagged:
self.tagged_count += 1
def clear_tagged(self):
def clear_tagged_txn():
if self.auto_delete:
self.tagged = []
self.tagged_count = 0
def get_by_name(cls, tag_name):
"""Get the list of tag objects that has the given tag_name.
tags = db.Query(cls).filter('tag =', tag_name).fetch(1000)
return tags
def get_by_scope_and_name(cls, scope, tag_name):
"""Get a tag by scope and name.
There may be only one such tag.
return db.Query(cls).filter(
'scope =', scope).filter('tag =', tag_name).get()
def get_by_scope(cls, scope):
"""Get a list of tag objects that has a given scope.
return db.Query(cls).filter('scope = ', scope).fetch(1000)
def get_tags_for_key(cls, key, limit=1000):
"""Get the tags for the datastore object represented by key.
tags = db.Query(cls).filter('tagged =', key).fetch(limit)
return tags
def get_for_custom_query(model, filter=None, order=None, limit=1000):
"""Get a list of tag objects for a custom filter.
query = db.Query(model)
if not filter:
filter = {}
for key, value in filter.iteritems():
if isinstance(value, list) and len(value) == 1:
value = value[0]
if isinstance(value, list):
op = '%s IN' % key
query.filter(op, value)
query.filter(key, value)
if not order:
order = []
for key in order:
return query.fetch(limit)
def get_tags_by_frequency(cls, limit=1000):
"""Return a list of Tags sorted by the number of objects to which they
have been applied, most frequently-used first. If limit is given, return
only return only that many tags; otherwise, return all.
tag_list = db.Query(cls).filter('tagged_count >', 0).order(
return tag_list
def get_tags_by_name(cls, limit=1000, ascending=True):
"""Return a list of Tags sorted alphabetically by the name of the tag.
If a limit is given, return only that many tags; otherwise, return all.
If ascending is True, sort from a-z; otherwise, sort from z-a.
from google.appengine.api import memcache
cache_name = cls.__name__ + '_tags_by_name'
if ascending:
cache_name += '_asc'
cache_name += '_desc'
tags = memcache.get(cache_name)
if tags is None or len(tags) < limit:
order_by = "tag"
if not ascending:
order_by = "-tag"
tags = db.Query(cls).order(order_by).fetch(limit)
memcache.add(cache_name, tags, 3600)
if len(tags) > limit:
# Return only as many as requested.
tags = tags[:limit]
return tags
def get_or_create(cls, scope, tag_name):
"""Get the Tag object that has the tag value given by tag_value.
tag_key_name = cls._key_name(scope.key().name(), tag_name)
existing_tag = cls.get_by_key_name(tag_key_name)
if existing_tag is None:
# the tag does not yet exist, so create it.
def create_tag_txn():
new_tag = cls(key_name=tag_key_name, tag=tag_name, scope=scope)
return new_tag
existing_tag = db.run_in_transaction(create_tag_txn)
return existing_tag
def copy_tag(cls, scope, tag_name, new_tag_name):
"""Copy a tag with a given scope and tag_name to another tag with
new tag_name.
tag = cls.get_by_scope_and_name(scope, tag_name)
if tag:
tag_key_name = cls._key_name(scope.key().name(), new_tag_name)
existing_tag = cls.get_by_key_name(tag_key_name)
if existing_tag is None:
new_tag = cls(key_name=tag_key_name, tag=new_tag_name, scope=scope,
added=tag.added, tagged=tag.tagged,
return new_tag
return existing_tag
return None
def delete_tag(cls, scope, tag_name):
"""Delete a tag with a given scope and tag_name.
tag = cls.get_by_scope_and_name(scope, tag_name)
if tag:
return True
return False
def popular_tags(cls, limit=5):
"""Get the most popular tags from memcache, or if they are not defined
there, it retrieves them from datastore and sets in memcache.
from google.appengine.api import memcache
tags = memcache.get(cls.__name__ + '_popular_tags')
if tags is None:
tags = cls.get_tags_by_frequency(limit)
memcache.add(cls.__name__ + '_popular_tags', tags, 3600)
return tags
def expire_cached_tags(cls):
"""Expire all tag lists which exist in memcache.
from google.appengine.api import memcache
memcache.delete(cls.__name__ + '_popular_tags')
memcache.delete(cls.__name__ + '_tags_by_name_asc')
memcache.delete(cls.__name__ + '_tags_by_name_desc')
def __str__(self):
"""Returns the string representation of the entity's tag name.
return self.tag
def tag_property(tag_name):
"""Decorator that creates and returns a tag property to be used
in Google AppEngine model.
tag_name: name of the tag to be created.
def get_tags(self):
""""Get a list of Tag objects for all Tags that apply to the
specified entity.
if self._tags[tag_name] is None or len(self._tags[tag_name]) == 0:
self._tags[tag_name] = self._tag_model[
return self._tags[tag_name]
def set_tags(self, seed):
"""Set a list of Tag objects for all Tags that apply to
the specified entity.
import types
if type(seed['tags']) is types.UnicodeType:
# Convert unicode to a plain string
seed['tags'] = str(seed['tags'])
if type(seed['tags']) is types.StringType:
# Tags is a string, split it on tag_seperator into a list
seed['tags'] = string.split(seed['tags'], self.tag_separator)
if type(seed['tags']) is types.ListType:
# Firstly, we will check to see if any tags have been removed.
# Iterate over a copy of _tags, as we may need to modify _tags
for each_tag in self._tags[tag_name][:]:
if each_tag not in seed['tags']:
# A tag that was previously assigned to this entity is
# missing in the list that is being assigned, so we
# disassocaite this entity and the tag.
# Secondly, we will check to see if any tags have been added.
for each_tag in seed['tags']:
each_tag = string.strip(each_tag)
if len(each_tag) > 0 and each_tag not in self._tags[tag_name]:
# A tag that was not previously assigned to this entity
# is present in the list that is being assigned, so we
# associate this entity with the tag.
tag = self._tag_model[tag_name].get_or_create(
seed['scope'], each_tag)
raise Exception, "tags must be either a unicode, a string or a list"
return property(get_tags, set_tags)
class Taggable(object):
"""A mixin class that is used for making GAE Model classes taggable.
This is an extended version of Taggable-mixin which allows for
multiple tag properties in the same AppEngine Model class.
def __init__(self, **kwargs):
"""The constructor class for Taggable, that creates a dictionary of tags.
The difference from the original taggable in terms of interface is
that, tag class is not used as the default tag model, since we don't
have a default tag property created in this class now.
kwargs: keywords containing the name of the tags and arguments
containing tag model to be used.
self._tags = {}
self._tag_model = {}
for tag_name in kwargs:
self._tags[tag_name] = None
self._tag_model[tag_name] = kwargs[tag_name]
self.tag_separator = ", "
def tags_string(self, tag_name, ret_list=False):
"""Create a formatted string version of this entity's tags.
tag_name: the name of the tag which must be formatted
ret_list: if False sends a string, otherwise sends a Python list
tag_list = [each_tag.tag for each_tag in tag_name]
if ret_list:
return tag_list
return self.tag_separator.join(tag_list)
def tags_class(self, tag_name):
"""Return a class instance object for a given tag name.
return self._tag_model[tag_name]