Adust the as_table tag to render a pick link if appropriate
The templates are adjusted to pass on a 'reference' value, which
is the url_name of the view from which the entity should be picked.
The as_table (and related) function(s) construct and then pass on
this argument and enable takes_contex so that we have access to the
context of the enclosing template.
We only extract ReferenceProperties that end with '_link_id' since
that is how all RP's are currently named. It is not possible to
create a field with the same name as the RP, as GAE will try to
interpret it's contents as the key of an entity before even calling
any function we can override.
Patch by: Sverre Rabbelier
"Database cache backend."
from django.core.cache.backends.base import BaseCache
from django.db import connection, transaction, DatabaseError
import base64, time
from datetime import datetime
try:
import cPickle as pickle
except ImportError:
import pickle
class CacheClass(BaseCache):
def __init__(self, table, params):
BaseCache.__init__(self, params)
self._table = table
max_entries = params.get('max_entries', 300)
try:
self._max_entries = int(max_entries)
except (ValueError, TypeError):
self._max_entries = 300
cull_frequency = params.get('cull_frequency', 3)
try:
self._cull_frequency = int(cull_frequency)
except (ValueError, TypeError):
self._cull_frequency = 3
def get(self, key, default=None):
cursor = connection.cursor()
cursor.execute("SELECT cache_key, value, expires FROM %s WHERE cache_key = %%s" % self._table, [key])
row = cursor.fetchone()
if row is None:
return default
now = datetime.now()
if row[2] < now:
cursor.execute("DELETE FROM %s WHERE cache_key = %%s" % self._table, [key])
transaction.commit_unless_managed()
return default
return pickle.loads(base64.decodestring(row[1]))
def set(self, key, value, timeout=None):
self._base_set('set', key, value, timeout)
def add(self, key, value, timeout=None):
return self._base_set('add', key, value, timeout)
def _base_set(self, mode, key, value, timeout=None):
if timeout is None:
timeout = self.default_timeout
cursor = connection.cursor()
cursor.execute("SELECT COUNT(*) FROM %s" % self._table)
num = cursor.fetchone()[0]
now = datetime.now().replace(microsecond=0)
exp = datetime.fromtimestamp(time.time() + timeout).replace(microsecond=0)
if num > self._max_entries:
self._cull(cursor, now)
encoded = base64.encodestring(pickle.dumps(value, 2)).strip()
cursor.execute("SELECT cache_key FROM %s WHERE cache_key = %%s" % self._table, [key])
try:
if mode == 'set' and cursor.fetchone():
cursor.execute("UPDATE %s SET value = %%s, expires = %%s WHERE cache_key = %%s" % self._table, [encoded, str(exp), key])
else:
cursor.execute("INSERT INTO %s (cache_key, value, expires) VALUES (%%s, %%s, %%s)" % self._table, [key, encoded, str(exp)])
except DatabaseError:
# To be threadsafe, updates/inserts are allowed to fail silently
return False
else:
transaction.commit_unless_managed()
return True
def delete(self, key):
cursor = connection.cursor()
cursor.execute("DELETE FROM %s WHERE cache_key = %%s" % self._table, [key])
transaction.commit_unless_managed()
def has_key(self, key):
cursor = connection.cursor()
cursor.execute("SELECT cache_key FROM %s WHERE cache_key = %%s" % self._table, [key])
return cursor.fetchone() is not None
def _cull(self, cursor, now):
if self._cull_frequency == 0:
cursor.execute("DELETE FROM %s" % self._table)
else:
cursor.execute("DELETE FROM %s WHERE expires < %%s" % self._table, [str(now)])
cursor.execute("SELECT COUNT(*) FROM %s" % self._table)
num = cursor.fetchone()[0]
if num > self._max_entries:
cursor.execute("SELECT cache_key FROM %s ORDER BY cache_key LIMIT 1 OFFSET %%s" % self._table, [num / self._cull_frequency])
cursor.execute("DELETE FROM %s WHERE cache_key < %%s" % self._table, [cursor.fetchone()[0]])