A minimal package for nested mutable datatypes in SQLAlchemy. Main feature is a JSON field that is RFC-7159 compliant.
Developed for SQLAlchemy v1.3.24. Your mileage may very with other versions.
$ pip install sqlalchemy-mutables
from sqlalchemy_mutables import NestedMutableListColumn
class MyTable(Base):
mutable_list = Column(NestedMutableListColumn)
from sqlalchemy_mutables import NestedMutableDictColumn
class MyTable(Base):
mutable_dict = Column(NestedMutableDictColumn)
To be compliant with RFC-7159, 'primitives' need to be supported as top level
values. These are values of type str|int|float|bool or None. Unfortunately,
these types break SQLAlchemy Mutable functionality
(specifically bool as this cannot be subclassed). To allow for these
while maintaining mutable functionality for list and dict, a wrapper class
has to be used via a hybrid_property.
from sqlalchemy_mutables import NestedMutableJSONColumn, NestedMutableJSONProperty
class MyTable(Base):
_mutable_json = Column("mutable_json", NestedMutableJSONColumn)
mutable_json = NestedMutableJSONProperty("_mutable_json")
It is possible to pass a custom functionality to the getter and/or setter:
def json_getter(value):
if isinstance(value, (int, float)):
value = value * 2
return value
def json_setter(value):
if isinstance(value, (int, float)):
value = value / 2
return value
class MyTable(Base):
...
mutable_json = NestedMutableJSONProperty(
"_mutable_json",
fget=json_getter,
fset=json_setter,
)
Passed functions are executed in the existing getter and setter in the form of
value = fc(value).