Package: serialchemy
SQLAlchemy model serialization.MotivationSerialchemywas developed as a module ofFlask-RESTAlchemy, a lib to create Restful APIs
using Flask and SQLAlchemy. We first triedmarshmallow-sqlalchemy, probably the most
well-known lib for SQLAlchemy model serialization, but we facedissues related to nested
models. We also think
that is possible to build a simpler and more maintainable solution by havingSQLAlchemyin
mind from the ground up, as opposed tomarshmallow-sqlalchemythat had to be
designed and built on top ofmarshmallow.How to Use itSerializing Generic TypesSuppose we have anEmployeeSQLAlchemymodel declared:classEmployee(Base):__tablename__="Employee"id=Column(Integer,primary_key=True)fullname=Column(String)admission=Column(DateTime,default=datetime(2000,1,1))company_id=Column(ForeignKey("Company.id"))company=relationship(Company)company_name=column_property(select([Company.name]).where(Company.id==company_id))password=Column(String)Generic Typesare automatically serialized byModelSerializer:fromserialchemyimportModelSerializeremp=Employee(fullname="Roberto Silva",admission=datetime(2019,4,2))serializer=ModelSerializer(Employee)serializer.dump(emp)# >>{"id":None,"fullname":"Roberto Silva","admission":"2019-04-02T00:00:00","company_id":None,"company_name":None,"password":None,}New items can be deserialized by the same serializer:new_employee={"fullname":"Jobson Gomes","admission":"2018-02-03"}serializer.load(new_employee)# >> <Employee object at 0x000001C119DE3940>Serializers do not commit into the database. You must do this by yourself:emp=serializer.load(new_employee)session.add(emp)session.commit()Custom SerializersFor anything beyondGeneric Typeswe must extend theModelSerializerclass:classEmployeeSerializer(ModelSerializer):password=Field(load_only=True)# passwords should be only deserializedcompany=NestedModelField(Company)# dump company as nested objectserializer=EmployeeSerializer(Employee)serializer.dump(emp)# >>{"id":1,"fullname":"Roberto Silva","admission":"2019-04-02T00:00:00","company":{"id":3,"name":"Acme Co"},}Extend Polymorphic SerializerOne of the possibilities is to serialize SQLalchemy joined table inheritance and
it child tables as well. To do such it’s necessary to set a variable with
the desired model class name. Take thisEmployeeclass with for instance and let us
assume it have a joined table inheritance:classEmployee(Base):...type=Column(String(50))__mapper_args__={"polymorphic_identity":"employee","polymorphic_on":type}classEngineer(Employee):__tablename__="Engineer"id=Column(Integer,ForeignKey("employee.id"),primary_key=True)association=relationship(Association)__mapper_args__={"polymorphic_identity":"engineer",}To use a extendedModelSerializerclass on theEngineerclass, you should create
the serializer as it follows:classEmployeeSerializer(PolymorphicModelSerializer):# Since this class will be polymorphicpassword=Field(load_only=True)company=NestedModelField(Company)classEngineerSerializer(EmployeeSerializer):__model_class__=Engineer# This is the table Serialchemy will refer toassociation=NestedModelField(Association)ContributingFor guidance on setting up a development environment and how to make a
contribution to serialchemy, see thecontributing guidelines.ReleaseA reminder for the maintainers on how to make a new release.Note that the VERSION should folow the semantic versioning as X.Y.Z
Ex.: v1.0.5Create arelease-VERSIONbranch fromupstream/master.UpdateCHANGELOG.rst.Push a branch with the changes.Once all builds pass, push aVERSIONtag toupstream.Merge the PR.History1.0.1 (2023-17-11)Fix license placement on setup.py1.0.0 (2023-14-11)Add support for SQLAlchemy imperative (classical) mappingDrop support for Python versions bellow 3.8Drop support for SQLAlchemy 1.30.4.0 (2023-12-11)Fix to get model attribute name instead of table column name on polymorphic serializerExtends the PolymorphicModelSerializer to accept also column descriptors when searching
for the polymorphic column key.Add support for serialization of Python EnumsChange PolymorphicModelSerializer to support inherited models of inherited modelsChange Field to use a default serializer for not None valuesAdded support for sqlalchemy 1.4Add EnumKeySerializer0.3.0 (2019-17-07)Add the composite fields to list of properties of model, to serialize that fields if it type is in EXTRA_SERIALIZERS.Fix error for SQLAlchemy composite attributesAdded free functions dump and load so users can quickly dump a SQLAlchemy model without having to instancialize
ModelSerializer.0.2.0 (2019-03-22)Fix: Error when deserializing of nested models when SQLAlchemy model primary
key attribute name differs from the column nameAllow EXTRA_SERIALIZERS to be defined in runtimeCheck if a session was given when serializing/deserializing nested fields0.1.0 (2019-02-12)First release on PyPI.