sqlalchemy_alembic_test.py

from sqlalchemy import create_engine, Column, types
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, scoped_session

Base = declarative_base()

class User(Base):
    __tablename__ = "user"
    id = Column(types.Integer, primary_key=True)
    name = Column(types.String(255), nullable=True, default=None, server_default='NULL')
    email = Column(types.String(255), unique=True, nullable=False)
    login = Column(types.String(255), unique=True)

# do not create any table
engine = create_engine('sqlite:///:memory:', echo=True)
session = scoped_session(sessionmaker(bind=engine))
Base.metadata.create_all(engine)

# check if column is (any) a primary_key or has unique constraint
# you can use User.__table__.c too, it is a alias to columns
result = dict([(c.name, any([c.primary_key, c.unique])) for c in User.__table__.columns])

print(result)

# also if you want to check only some columns:
for column_name in ['name', 'id', 'email', 'login']:
    c = User.__table__.columns.get(column_name)
    print("Column %r has an unique constraint: %s" %(column_name, any([c.primary_key, c.unique])))
    
engine = create_engine('mysql:///test?unix_socket=/tmp/mysql/socket', echo=True)
#######################################################

from sqlalchemy import create_engine, Column, types
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, scoped_session

Base = declarative_base()

class User(Base):
    __tablename__ = "user"
    id = Column(types.Integer, primary_key=True)
    
engine = create_engine('mysql:///test?unix_socket=/tmp/mysql/socket', echo=True)
session = scoped_session(sessionmaker(bind=engine))
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)


from alembic.migration import MigrationContext
from alembic.operations import Operations

ctx = MigrationContext.configure(engine)
op = Operations(ctx)

with op.batch_alter_table("user") as batch_op:
    batch_op.add_column(Column('foo', types.Integer))
    batch_op.add_column(Column('bar', types.Integer))