Best way to do enum in Sqlalchemy?

Best way to do enum in Sqlalchemy?

In SQLAlchemy, you can create an enum-like behavior for database columns using Python's Enum from the enum module or by using custom SQLAlchemy types. Here, I'll show you two approaches:

1. Using Python Enum:

You can use Python's built-in Enum from the enum module to create an enumeration-like behavior for SQLAlchemy columns. Here's an example:

from enum import Enum as PyEnum from sqlalchemy import create_engine, Column, Integer, String from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class MyEnum(PyEnum): ENUM_VALUE1 = "Value 1" ENUM_VALUE2 = "Value 2" ENUM_VALUE3 = "Value 3" class MyModel(Base): __tablename__ = 'my_table' id = Column(Integer, primary_key=True) enum_column = Column(String(50), nullable=False) # Create a SQLite in-memory database engine = create_engine('sqlite:///:memory:') # Create the table Base.metadata.create_all(engine) # Insert data Session = sessionmaker(bind=engine) session = Session() session.add(MyModel(enum_column=MyEnum.ENUM_VALUE1)) session.add(MyModel(enum_column=MyEnum.ENUM_VALUE2)) session.add(MyModel(enum_column=MyEnum.ENUM_VALUE3)) session.commit() # Query data results = session.query(MyModel).filter_by(enum_column=MyEnum.ENUM_VALUE2).all() for result in results: print(result.id, result.enum_column)

2. Using Custom SQLAlchemy Types:

Another way is to use custom SQLAlchemy types. This approach allows you to create custom column types that represent enum-like behavior. Here's an example:

from sqlalchemy import create_engine, Column from sqlalchemy.types import TypeDecorator, String from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class MyEnum(TypeDecorator): impl = String(50) def process_bind_param(self, value, dialect): if value is not None: return value.value def process_result_value(self, value, dialect): if value is not None: return MyEnumEnum(value) class MyEnumEnum: ENUM_VALUE1 = "Value 1" ENUM_VALUE2 = "Value 2" ENUM_VALUE3 = "Value 3" class MyModel(Base): __tablename__ = 'my_table' id = Column(Integer, primary_key=True) enum_column = Column(MyEnum, nullable=False) # Create a SQLite in-memory database engine = create_engine('sqlite:///:memory:') # Create the table Base.metadata.create_all(engine) # Insert data Session = sessionmaker(bind=engine) session = Session() session.add(MyModel(enum_column=MyEnumEnum.ENUM_VALUE1)) session.add(MyModel(enum_column=MyEnumEnum.ENUM_VALUE2)) session.add(MyModel(enum_column=MyEnumEnum.ENUM_VALUE3)) session.commit() # Query data results = session.query(MyModel).filter_by(enum_column=MyEnumEnum.ENUM_VALUE2).all() for result in results: print(result.id, result.enum_column)

Both of these approaches allow you to use enum-like values in your SQLAlchemy models. Choose the one that best fits your needs and coding style.

Examples

  1. How to define enums in SQLAlchemy with Python:

    • Description: Users are searching for the best approach to define enums in SQLAlchemy using Python.
    • Code Implementation:
      from sqlalchemy import Enum, create_engine, Column, Integer from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(Enum('active', 'inactive', name='status_enum')) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  2. SQLAlchemy enum best practices:

    • Description: This query seeks best practices for defining enums in SQLAlchemy.
    • Code Implementation:
      from enum import Enum from sqlalchemy import Column, Integer, Enum as SQLAlchemyEnum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Status(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(SQLAlchemyEnum(Status), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  3. How to create enum types in SQLAlchemy:

    • Description: Users are looking for information on creating enum types within SQLAlchemy.
    • Code Implementation:
      from sqlalchemy import create_engine, MetaData, Table, Column, Enum engine = create_engine('sqlite:///:memory:') metadata = MetaData() my_table = Table('my_table', metadata, Column('id', Integer, primary_key=True), Column('status', Enum('active', 'inactive')) ) metadata.create_all(engine)

  4. Defining custom enum types in SQLAlchemy:

    • Description: This query aims to understand how to define custom enum types in SQLAlchemy.
    • Code Implementation:
      from enum import Enum from sqlalchemy import Column, Integer, Enum as SQLAlchemyEnum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Status(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(SQLAlchemyEnum(Status), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  5. Using enums in SQLAlchemy models:

    • Description: Users are interested in using enums effectively within SQLAlchemy models.
    • Code Implementation:
      from enum import Enum from sqlalchemy import Column, Integer, Enum as SQLAlchemyEnum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Status(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(SQLAlchemyEnum(Status), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  6. SQLAlchemy enum vs. ChoiceType:

    • Description: This query compares SQLAlchemy enum with ChoiceType and seeks the best option.
    • Code Implementation:
      from sqlalchemy import Column, Integer, create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy_utils import ChoiceType Base = declarative_base() class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(ChoiceType({'active': 'active', 'inactive': 'inactive'}), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  7. How to use Enum in SQLAlchemy for database schema:

    • Description: Users want to know how to incorporate enums into their SQLAlchemy database schemas effectively.
    • Code Implementation:
      from sqlalchemy import Column, Integer, Enum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class StatusEnum(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(Enum(StatusEnum), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  8. Defining enum types with SQLAlchemy:

    • Description: This query focuses on how to define enum types using SQLAlchemy for database schemas.
    • Code Implementation:
      from enum import Enum from sqlalchemy import Column, Integer, Enum as SQLAlchemyEnum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Status(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(SQLAlchemyEnum(Status), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  9. SQLAlchemy enum constraints:

    • Description: Users are searching for information on how to impose constraints on enums in SQLAlchemy.
    • Code Implementation:
      from sqlalchemy import Column, Integer, Enum, create_engine from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class StatusEnum(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(Enum(StatusEnum), nullable=False) engine = create_engine('sqlite:///:memory:') Base.metadata.create_all(engine)

  10. SQLAlchemy enum data manipulation:

    • Description: This query aims to understand how to manipulate data with enums in SQLAlchemy.
    • Code Implementation:
      from sqlalchemy import create_engine, Column, Integer, Enum from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class StatusEnum(Enum): ACTIVE = 'active' INACTIVE = 'inactive' class MyModel(Base): __tablename__ = 'mymodel' id = Column(Integer, primary_key=True) status = Column(Enum(StatusEnum), nullable=False) engine = create_engine('sqlite:///:memory:') Session = sessionmaker(bind=engine) Base.metadata.create_all(engine)

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