Alembic autogenerate does not generate upgrade script - postgresql

Question

I am using sqlalchemy and postgressql in Flask application. The migration tool that I am using is alembic=0.6.3.
if I type alembic current it shows me:
Current revision for postgres://localhost/myDb: None
which is correct database connection. But when I run alembic revision --autogenerate -m 'Add user table' it generates the default alembic template without any sql commands in it. Like:
"""Add user table
Revision ID: 59b6d3503442
Revises: None
Create Date: 2015-04-06 13:42:24.540005
"""
# revision identifiers, used by Alembic.
revision = '59b6d3503442'
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 ###
I couldn't find any proper solution in SO.
Here is my env.py:
from __future__ import with_statement
from logging.config import fileConfig
import os
import sys
import warnings
from alembic import context
from sqlalchemy import create_engine, pool
from sqlalchemy.exc import SAWarning
ROOT = os.path.abspath(
os.path.join(os.path.dirname(__file__), os.pardir, os.pardir)
)
sys.path.append(ROOT)
from myApp import Application
from myApp.extensions import db
# Don't raise exception on `SAWarning`s. For example, if Alembic does
# not recognize some column types when autogenerating migrations,
# Alembic would otherwise crash with SAWarning.
warnings.simplefilter('ignore', SAWarning)
app = Application()
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)
target_metadata = db.metadata
def run_migrations_offline():
"""Run migrations in 'offline' mode.
This configures the context with just a URL
and not an Engine, though an Engine is acceptable
here as well. By skipping the Engine creation
we don't even need a DBAPI to be available.
Calls to context.execute() here emit the given string to the
script output.
"""
url = app.config['SQLALCHEMY_DATABASE_URI']
context.configure(url=url)
with context.begin_transaction():
context.run_migrations()
def run_migrations_online():
"""Run migrations in 'online' mode.
In this scenario we need to create an Engine
and associate a connection with the context.
"""
url = app.config['SQLALCHEMY_DATABASE_URI']
engine = create_engine(url, poolclass=pool.NullPool)
connection = engine.connect()
context.configure(
connection=connection,
target_metadata=target_metadata
)
try:
with context.begin_transaction():
context.run_migrations()
finally:
connection.close()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
and this is my alembic.ini:
# A generic, single database configuration.
[alembic]
# path to migration scripts
script_location = myApp/migrations
# template used to generate migration files
# file_template = %%(rev)s_%%(slug)s
# Logging configuration
[loggers]
keys = root,sqlalchemy,alembic
[handlers]
keys = console
[formatters]
keys = generic
[logger_root]
level = WARN
handlers = console
qualname =
[logger_sqlalchemy]
level = WARN
handlers =
qualname = sqlalchemy.engine
[logger_alembic]
level = INFO
handlers =
qualname = alembic
[handler_console]
class = StreamHandler
args = (sys.stderr,)
level = NOTSET
formatter = generic
[formatter_generic]
format = %(levelname)-5.5s [%(name)s] %(message)s
datefmt = %H:%M:%S
Addition files for more information
This is the extensions.py file from where I import db for metadata:
from flask.ext.sqlalchemy import SQLAlchemy
from raven.contrib.flask import Sentry
from sqlalchemy_utils import force_instant_defaults
db = SQLAlchemy()
sentry = Sentry()
force_instant_defaults()
and this the model user.py file:
#
-*- coding: utf-8 -*-
from datetime import datetime
from flask.ext.login import UserMixin
from sqlalchemy_utils.types.password import PasswordType
from ..extensions import db
class User(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(
db.Unicode(255),
nullable=False
)
surname = db.Column(
db.Unicode(255),
nullable=False
)
email = db.Column(
db.Unicode(255),
nullable=False,
unique=True
)
password = db.Column(
PasswordType(128, schemes=['sha512_crypt']),
nullable=False
)
created_at = db.Column(
db.DateTime,
nullable=False,
default=datetime.utcnow
)
def is_active(self):
return True
def __repr__(self):
return '<{cls} email={email!r}>'.format(
cls=self.__class__.__name__,
email=self.email,
)
def __str__(self):
return unicode(self).encode('utf8')
def __unicode__(self):
return self.email