132 lines
4.8 KiB
Python
132 lines
4.8 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import json
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from sqlalchemy.dialects import mysql
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from sqlalchemy.types import Integer, Text, TypeDecorator, String as _String
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class JsonEncodedType(TypeDecorator):
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"""Base column type for data serialized as JSON-encoded string in db."""
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type = None
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impl = Text
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cache_ok = True
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"""This type is safe to cache."""
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def __init__(self, mysql_as_long=False, mysql_as_medium=False):
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"""Initialize JSON-encoding type."""
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super(JsonEncodedType, self).__init__()
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if mysql_as_long and mysql_as_medium:
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raise TypeError("mysql_as_long and mysql_as_medium are mutually "
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"exclusive")
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if mysql_as_long:
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self.impl = Text().with_variant(mysql.LONGTEXT(), 'mysql')
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elif mysql_as_medium:
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self.impl = Text().with_variant(mysql.MEDIUMTEXT(), 'mysql')
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def process_bind_param(self, value, dialect):
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"""Bind parameters to the process."""
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if value is None:
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if self.type is not None:
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# Save default value according to current type to keep the
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# interface consistent.
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value = self.type()
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elif self.type is not None and not isinstance(value, self.type):
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raise TypeError("%s supposes to store %s objects, but %s given"
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% (self.__class__.__name__,
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self.type.__name__,
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type(value).__name__))
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serialized_value = json.dumps(value)
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return serialized_value
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def process_result_value(self, value, dialect):
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"""Process result value."""
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if value is not None:
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value = json.loads(value)
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return value
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class JsonEncodedDict(JsonEncodedType):
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"""Represents dict serialized as json-encoded string in db.
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Note that this type does NOT track mutations. If you want to update it, you
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have to assign existing value to a temporary variable, update, then assign
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back. See this page for more robust work around:
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http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
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"""
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type = dict
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class JsonEncodedList(JsonEncodedType):
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"""Represents list serialized as json-encoded string in db.
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Note that this type does NOT track mutations. If you want to update it, you
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have to assign existing value to a temporary variable, update, then assign
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back. See this page for more robust work around:
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http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
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"""
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type = list
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class SoftDeleteInteger(TypeDecorator):
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"""Coerce a bound param to be a proper integer before passing it to DBAPI.
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Some backends like PostgreSQL are very strict about types and do not
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perform automatic type casts, e.g. when trying to INSERT a boolean value
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like ``false`` into an integer column. Coercing of the bound param in DB
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layer by the means of a custom SQLAlchemy type decorator makes sure we
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always pass a proper integer value to a DBAPI implementation.
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This is not a general purpose boolean integer type as it specifically
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allows for arbitrary positive integers outside of the boolean int range
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(0, 1, False, True), so that it's possible to have compound unique
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constraints over multiple columns including ``deleted`` (e.g. to
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soft-delete flavors with the same name in Nova without triggering
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a constraint violation): ``deleted`` is set to be equal to a PK
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int value on deletion, 0 denotes a non-deleted row.
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"""
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impl = Integer
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cache_ok = True
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"""This type is safe to cache."""
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def process_bind_param(self, value, dialect):
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"""Return the binding parameter."""
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if value is None:
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return None
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return int(value)
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class String(_String):
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"""String subclass that implements oslo_db specific options.
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Initial goal is to support ndb-specific flags.
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mysql_ndb_type is used to override the String with another data type.
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mysql_ndb_size is used to adjust the length of the String.
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"""
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def __init__(
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self, length, mysql_ndb_length=None, mysql_ndb_type=None, **kw):
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"""Initialize options."""
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super(String, self).__init__(length, **kw)
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self.mysql_ndb_type = mysql_ndb_type
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self.mysql_ndb_length = mysql_ndb_length
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