How do I set attribute default values in sqlalchemy declarative?

Question

In SQLAlchemy Declarative, how do I set up default values for columns, such that transient or pending object instances will have those default values? A short example:

Answer 1

Add a constructor to your class and set the default value there. The constructor doesn't run when the rows are loaded from the database so it is fine to do this.

class A(Base):
    __tablename__ = "A"
    id = Column(Integer, primary_key=True)
    word = Column(String)

    def __init__(self):
        self.word = "adefault"

a = A()
print a.word

There are examples of using __init__ in similar ways in the SA Docs.