Alembic --autogenerate producing empty migration

Question

I am trying to use Alembic for the first time and want to use --autogenerate feature described here

My project structure looks like

project/        configuration/                     __init__.py                     dev.py                     test.py        core/            app/               models/                     __init__.py                     user.py        db/           alembic/                   versions/                   env.py           alembic.ini 

I am using Flask and SQLAlchemy and their Flask-SQLAlchemy extension. my model User looks like

class User(UserMixin, db.Model):     __tablename__ = 'users'     # noinspection PyShadowingBuiltins     uuid = Column('uuid', GUID(), default=uuid.uuid4, primary_key=True,                   unique=True)     email = Column('email', String, nullable=False, unique=True)     _password = Column('password', String, nullable=False)     created_on = Column('created_on', sa.types.DateTime(timezone=True),                         default=datetime.utcnow())     last_login = Column('last_login', sa.types.DateTime(timezone=True),                         onupdate=datetime.utcnow()) 

As described here, I modified env.py to look like

from configuration import app  alembic_config = config.get_section(config.config_ini_section) alembic_config['sqlalchemy.url'] = app.config['SQLALCHEMY_DATABASE_URI'] engine = engine_from_config(     alembic_config,             prefix='sqlalchemy.',             poolclass=pool.NullPool) 

and

from configuration import db   target_metadata = db.metadata 

where configuration.__init__py looks like

from flask import Flask from flask.ext.sqlalchemy import SQLAlchemy import dev   app = Flask(__name__) app.config.from_envvar('SETTINGS_PT') db = SQLAlchemy(app) 

Now when I run migration

$alembic revision --autogenerate -m "Added user table" INFO  [alembic.migration] Context impl PostgresqlImpl. INFO  [alembic.migration] Will assume transactional DDL.   Generating /Users/me/IdeaProjects/project/db/alembic/versions/55a9d5   35d8ae_added_user_table.py...done 

but file alembic/versions/55a9d5 has empty upgrade() and downgrade() methods

"""Added user table  Revision ID: 1b62a62eef0d Revises: None Create Date: 2013-03-27 06:37:08.314177  """  # revision identifiers, used by Alembic. revision = '1b62a62eef0d' down_revision = None  from alembic import op import sqlalchemy as sa   def upgrade():     ### commands auto generated by Alembic - please adjust! ###     pass     ### end Alembic commands ###   def downgrade():     ### commands auto generated by Alembic - please adjust! ###     pass     ### end Alembic commands ### 

How come it is not able to understand that there is a new User model? Please help

Answer 1

As per @zzzeek, after I included the following in my env.py, I was able to work with --autogenerate option

in env.py under run_migrations_online()

from configuration import app from core.expense.models import user # added my model here  alembic_config = config.get_section(config.config_ini_section) alembic_config['sqlalchemy.url'] = app.config['SQLALCHEMY_DATABASE_URI'] engine = engine_from_config(     alembic_config,     prefix='sqlalchemy.',     poolclass=pool.NullPool) 

then I ran alembic revision --autogenerate -m "Added initial table" and got

def upgrade():     ### commands auto generated by Alembic - please adjust! ###     op.create_table('users',     sa.Column('uuid', sa.GUID(), nullable=False),     sa.Column('email', sa.String(), nullable=False),     sa.Column('password', sa.String(), nullable=False),     sa.Column('created_on', sa.DateTime(timezone=True), nullable=True),     sa.Column('last_login', sa.DateTime(timezone=True), nullable=True),     sa.PrimaryKeyConstraint('uuid'),     sa.UniqueConstraint('email'),     sa.UniqueConstraint('uuid')     )     ### end Alembic commands ### 

Thank you Michael for all your help!