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# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import json
from sqlalchemy.types import Integer, TypeDecorator, Text
from sqlalchemy.dialects import mysql
class JsonEncodedType(TypeDecorator):
"""Base column type for data serialized as JSON-encoded string in db."""
type = None
impl = Text
def __init__(self, mysql_as_long=False, mysql_as_medium=False):
super(JsonEncodedType, self).__init__()
if mysql_as_long and mysql_as_medium:
raise TypeError("mysql_as_long and mysql_as_medium are mutually "
"exclusive")
if mysql_as_long:
self.impl = Text().with_variant(mysql.LONGTEXT(), 'mysql')
elif mysql_as_medium:
self.impl = Text().with_variant(mysql.MEDIUMTEXT(), 'mysql')
def process_bind_param(self, value, dialect):
if value is None:
if self.type is not None:
# Save default value according to current type to keep the
# interface consistent.
value = self.type()
elif self.type is not None and not isinstance(value, self.type):
raise TypeError("%s supposes to store %s objects, but %s given"
% (self.__class__.__name__,
self.type.__name__,
type(value).__name__))
serialized_value = json.dumps(value)
return serialized_value
def process_result_value(self, value, dialect):
if value is not None:
value = json.loads(value)
return value
class JsonEncodedDict(JsonEncodedType):
"""Represents dict serialized as json-encoded string in db.
Note that this type does NOT track mutations. If you want to update it, you
have to assign existing value to a temporary variable, update, then assign
back. See this page for more robust work around:
http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
"""
type = dict
class JsonEncodedList(JsonEncodedType):
"""Represents list serialized as json-encoded string in db.
Note that this type does NOT track mutations. If you want to update it, you
have to assign existing value to a temporary variable, update, then assign
back. See this page for more robust work around:
http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
"""
type = list
class SoftDeleteInteger(TypeDecorator):
"""Coerce a bound param to be a proper integer before passing it to DBAPI.
Some backends like PostgreSQL are very strict about types and do not
perform automatic type casts, e.g. when trying to INSERT a boolean value
like ``false`` into an integer column. Coercing of the bound param in DB
layer by the means of a custom SQLAlchemy type decorator makes sure we
always pass a proper integer value to a DBAPI implementation.
"""
impl = Integer
def process_bind_param(self, value, dialect):
return int(value)
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