Viewing file:  kv.py (5.48 KB) -rw-r--r--
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import operator
from peewee import *
from peewee import sqlite3
from peewee import Expression
from playhouse.fields import PickleField
try:
from playhouse.sqlite_ext import CSqliteExtDatabase as SqliteExtDatabase
except ImportError:
from playhouse.sqlite_ext import SqliteExtDatabase
Sentinel = type('Sentinel', (object,), {})
class KeyValue(object):
"""
Persistent dictionary.
:param Field key_field: field to use for key. Defaults to CharField.
:param Field value_field: field to use for value. Defaults to PickleField.
:param bool ordered: data should be returned in key-sorted order.
:param Database database: database where key/value data is stored.
:param str table_name: table name for data.
"""
def __init__(self, key_field=None, value_field=None, ordered=False,
database=None, table_name='keyvalue'):
if key_field is None:
key_field = CharField(max_length=255, primary_key=True)
if not key_field.primary_key:
raise ValueError('key_field must have primary_key=True.')
if value_field is None:
value_field = PickleField()
self._key_field = key_field
self._value_field = value_field
self._ordered = ordered
self._database = database or SqliteExtDatabase(':memory:')
self._table_name = table_name
support_on_conflict = (isinstance(self._database, PostgresqlDatabase) or
(isinstance(self._database, SqliteDatabase) and
self._database.server_version >= (3, 24)))
if support_on_conflict:
self.upsert = self._postgres_upsert
self.update = self._postgres_update
else:
self.upsert = self._upsert
self.update = self._update
self.model = self.create_model()
self.key = self.model.key
self.value = self.model.value
# Ensure table exists.
self.model.create_table()
def create_model(self):
class KeyValue(Model):
key = self._key_field
value = self._value_field
class Meta:
database = self._database
table_name = self._table_name
return KeyValue
def query(self, *select):
query = self.model.select(*select).tuples()
if self._ordered:
query = query.order_by(self.key)
return query
def convert_expression(self, expr):
if not isinstance(expr, Expression):
return (self.key == expr), True
return expr, False
def __contains__(self, key):
expr, _ = self.convert_expression(key)
return self.model.select().where(expr).exists()
def __len__(self):
return len(self.model)
def __getitem__(self, expr):
converted, is_single = self.convert_expression(expr)
query = self.query(self.value).where(converted)
item_getter = operator.itemgetter(0)
result = [item_getter(row) for row in query]
if len(result) == 0 and is_single:
raise KeyError(expr)
elif is_single:
return result[0]
return result
def _upsert(self, key, value):
(self.model
.insert(key=key, value=value)
.on_conflict('replace')
.execute())
def _postgres_upsert(self, key, value):
(self.model
.insert(key=key, value=value)
.on_conflict(conflict_target=[self.key],
preserve=[self.value])
.execute())
def __setitem__(self, expr, value):
if isinstance(expr, Expression):
self.model.update(value=value).where(expr).execute()
else:
self.upsert(expr, value)
def __delitem__(self, expr):
converted, _ = self.convert_expression(expr)
self.model.delete().where(converted).execute()
def __iter__(self):
return iter(self.query().execute())
def keys(self):
return map(operator.itemgetter(0), self.query(self.key))
def values(self):
return map(operator.itemgetter(0), self.query(self.value))
def items(self):
return iter(self.query().execute())
def _update(self, __data=None, **mapping):
if __data is not None:
mapping.update(__data)
return (self.model
.insert_many(list(mapping.items()),
fields=[self.key, self.value])
.on_conflict('replace')
.execute())
def _postgres_update(self, __data=None, **mapping):
if __data is not None:
mapping.update(__data)
return (self.model
.insert_many(list(mapping.items()),
fields=[self.key, self.value])
.on_conflict(conflict_target=[self.key],
preserve=[self.value])
.execute())
def get(self, key, default=None):
try:
return self[key]
except KeyError:
return default
def setdefault(self, key, default=None):
try:
return self[key]
except KeyError:
self[key] = default
return default
def pop(self, key, default=Sentinel):
with self._database.atomic():
try:
result = self[key]
except KeyError:
if default is Sentinel:
raise
return default
del self[key]
return result
def clear(self):
self.model.delete().execute()
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