Using getters and setters with SQLAlchemy

getter_and_setter.py

class Table(Base):
    id = Column(Integer, primary_key=True)
    _name = Column('name', String(24))

    @property
    def name(self):
        return self._name;

    @name.setter
    def name(self, value):
        self._name = value.title()

#A query you might perform on the table.
#It won't work anymore :'(
query = db_session.query(Table)\
        .filter(Table.name == 'Theron')

#You could do this, but it doesn't look as nice, is inconsistent with the "id"
#column, and you'd have to update all your existing code.
query = db_session.query(Table)\
        .filter(Table._name == 'Theron')

synonym.py

from sqlalchemy.orm import synonym

class Table(Base):
    id = Column(Integer, primary_key=True)
    _name = Column('name', String(24))

    @property
    def name(self):
        return self._name;

    @name.setter
    def name(self, value):
        self._name = value.title()

    name = synonym('_name', descriptor=name)

#A query you might perform on the table.
#Now it works again! :)
query = db_session.query(Table)\
        .filter(Table.name == 'Theron')

table.py

class Table(Base):
    id = Column(Integer, primary_key=True)
    name = Column(String(24))

#A query you might perform on the table.
query = db_session.query(Table)\
        .filter(Table.name == 'Theron')

Confirming that the synonym method works great!

Let me add my thanks for doing this.

I wanted to define a computed attribute that is not in db, with a setter to override the value. I introduced an instance variable _paid as shown below. (Did not need to use synonym, not clear on that)

# coding: utf-8

from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.hybrid import hybrid_property

Base = declarative_base()
metadata = Base.metadata


class Customer(Base):
    __tablename__ = 'Customer'

    Id = Column(String(8000), primary_key=True)
    OrderCount = Column(Integer)
    UnpaidOrderCount = Column(Integer)

    @hybrid_property
    def paid(self):
        if not hasattr(self, "_paid"):
            self._paid = self.OrderCount - self.UnpaidOrderCount
        return self._paid

    @paid.setter
    def paid(self, value):
        self._paid = value