jsonalchemy: add de_coerce to reverse serialization of list and dict elements from Mutation objects back to original state.

rhodecode/lib/jsonalchemy.py

@@ -1,265 +1,274 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2010-2017 RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 import collections
 
 import sqlalchemy
 from sqlalchemy import UnicodeText
 from sqlalchemy.ext.mutable import Mutable
 
 from rhodecode.lib.ext_json import json
 
 
 class JsonRaw(unicode):
     """
     Allows interacting with a JSON types field using a raw string.
 
     For example::
         db_instance = JsonTable()
         db_instance.enabled = True
         db_instance.json_data = JsonRaw('{"a": 4}')
 
     This will bypass serialization/checks, and allow storing
     raw values
     """
     pass
 
 
 # Set this to the standard dict if Order is not required
 DictClass = collections.OrderedDict
 
 
 class JSONEncodedObj(sqlalchemy.types.TypeDecorator):
     """
     Represents an immutable structure as a json-encoded string.
 
     If default is, for example, a dict, then a NULL value in the
     database will be exposed as an empty dict.
     """
 
     impl = UnicodeText
     safe = True
 
     def __init__(self, *args, **kwargs):
         self.default = kwargs.pop('default', None)
         self.safe = kwargs.pop('safe_json', self.safe)
         self.dialect_map = kwargs.pop('dialect_map', {})
         super(JSONEncodedObj, self).__init__(*args, **kwargs)
 
     def load_dialect_impl(self, dialect):
         if dialect.name in self.dialect_map:
             return dialect.type_descriptor(self.dialect_map[dialect.name])
         return dialect.type_descriptor(self.impl)
 
     def process_bind_param(self, value, dialect):
         if isinstance(value, JsonRaw):
             value = value
         elif value is not None:
             value = json.dumps(value)
         return value
 
     def process_result_value(self, value, dialect):
         if self.default is not None and (not value or value == '""'):
             return self.default()
 
         if value is not None:
             try:
                 value = json.loads(value, object_pairs_hook=DictClass)
             except Exception as e:
                 if self.safe and self.default is not None:
                     return self.default()
                 else:
                     raise
         return value
 
 
 class MutationObj(Mutable):
     @classmethod
     def coerce(cls, key, value):
         if isinstance(value, dict) and not isinstance(value, MutationDict):
             return MutationDict.coerce(key, value)
         if isinstance(value, list) and not isinstance(value, MutationList):
             return MutationList.coerce(key, value)
         return value
 
+    def de_coerce(self):
+        return self
+
     @classmethod
     def _listen_on_attribute(cls, attribute, coerce, parent_cls):
         key = attribute.key
         if parent_cls is not attribute.class_:
             return
 
         # rely on "propagate" here
         parent_cls = attribute.class_
 
         def load(state, *args):
             val = state.dict.get(key, None)
             if coerce:
                 val = cls.coerce(key, val)
                 state.dict[key] = val
             if isinstance(val, cls):
                 val._parents[state.obj()] = key
 
         def set(target, value, oldvalue, initiator):
             if not isinstance(value, cls):
                 value = cls.coerce(key, value)
             if isinstance(value, cls):
                 value._parents[target.obj()] = key
             if isinstance(oldvalue, cls):
                 oldvalue._parents.pop(target.obj(), None)
             return value
 
         def pickle(state, state_dict):
             val = state.dict.get(key, None)
             if isinstance(val, cls):
                 if 'ext.mutable.values' not in state_dict:
                     state_dict['ext.mutable.values'] = []
                 state_dict['ext.mutable.values'].append(val)
 
         def unpickle(state, state_dict):
             if 'ext.mutable.values' in state_dict:
                 for val in state_dict['ext.mutable.values']:
                     val._parents[state.obj()] = key
 
         sqlalchemy.event.listen(parent_cls, 'load', load, raw=True,
                                 propagate=True)
         sqlalchemy.event.listen(parent_cls, 'refresh', load, raw=True,
                                 propagate=True)
         sqlalchemy.event.listen(parent_cls, 'pickle', pickle, raw=True,
                                 propagate=True)
         sqlalchemy.event.listen(attribute, 'set', set, raw=True, retval=True,
                                 propagate=True)
         sqlalchemy.event.listen(parent_cls, 'unpickle', unpickle, raw=True,
                                 propagate=True)
 
 
 class MutationDict(MutationObj, DictClass):
     @classmethod
     def coerce(cls, key, value):
         """Convert plain dictionary to MutationDict"""
         self = MutationDict(
             (k, MutationObj.coerce(key, v)) for (k, v) in value.items())
         self._key = key
         return self
 
+    def de_coerce(self):
+        return dict(self)
+
     def __setitem__(self, key, value):
         # Due to the way OrderedDict works, this is called during __init__.
         # At this time we don't have a key set, but what is more, the value
         # being set has already been coerced. So special case this and skip.
         if hasattr(self, '_key'):
             value = MutationObj.coerce(self._key, value)
         DictClass.__setitem__(self, key, value)
         self.changed()
 
     def __delitem__(self, key):
         DictClass.__delitem__(self, key)
         self.changed()
 
     def __setstate__(self, state):
         self.__dict__ = state
 
     def __reduce_ex__(self, proto):
         # support pickling of MutationDicts
         d = dict(self)
         return (self.__class__, (d, ))
 
 
 class MutationList(MutationObj, list):
     @classmethod
     def coerce(cls, key, value):
         """Convert plain list to MutationList"""
         self = MutationList((MutationObj.coerce(key, v) for v in value))
         self._key = key
         return self
 
+    def de_coerce(self):
+        return list(self)
+
     def __setitem__(self, idx, value):
         list.__setitem__(self, idx, MutationObj.coerce(self._key, value))
         self.changed()
 
     def __setslice__(self, start, stop, values):
         list.__setslice__(self, start, stop,
                           (MutationObj.coerce(self._key, v) for v in values))
         self.changed()
 
     def __delitem__(self, idx):
         list.__delitem__(self, idx)
         self.changed()
 
     def __delslice__(self, start, stop):
         list.__delslice__(self, start, stop)
         self.changed()
 
     def append(self, value):
         list.append(self, MutationObj.coerce(self._key, value))
         self.changed()
 
     def insert(self, idx, value):
         list.insert(self, idx, MutationObj.coerce(self._key, value))
         self.changed()
 
     def extend(self, values):
         list.extend(self, (MutationObj.coerce(self._key, v) for v in values))
         self.changed()
 
     def pop(self, *args, **kw):
         value = list.pop(self, *args, **kw)
         self.changed()
         return value
 
     def remove(self, value):
         list.remove(self, value)
         self.changed()
 
 
 def JsonType(impl=None, **kwargs):
     """
     Helper for using a mutation obj, it allows to use .with_variant easily.
     example::
 
         settings = Column('settings_json',
             MutationObj.as_mutable(
             JsonType(dialect_map=dict(mysql=UnicodeText(16384))))
     """
 
     if impl == 'list':
         return JSONEncodedObj(default=list, **kwargs)
     elif impl == 'dict':
         return JSONEncodedObj(default=DictClass, **kwargs)
     else:
         return JSONEncodedObj(**kwargs)
 
 
 JSON = MutationObj.as_mutable(JsonType())
 """
 A type to encode/decode JSON on the fly
 
 sqltype is the string type for the underlying DB column::
 
     Column(JSON) (defaults to UnicodeText)
 """
 
 JSONDict = MutationObj.as_mutable(JsonType('dict'))
 """
 A type to encode/decode JSON dictionaries on the fly
 """
 
 JSONList = MutationObj.as_mutable(JsonType('list'))
 """
 A type to encode/decode JSON lists` on the fly
 """