I'm using Flask with Flask-SQLAlchemy and Flask-Migrate to create an application, however when I try to create a migration nothing happens.
I've created two tables in app/models.py:
from flask import current_app
from . import db
class Student(db.Model):
__tablename__ = 'students'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(64), unique=True, nullable=False)
password_hash = db.Column(db.String(128))
def __init__(self, **kwargs):
super(Student, self).__init__(**kwargs)
def __repr__(self):
return '<Tutor {}>' % self.id
class Tutor(db.Model):
__tablename__ = 'tutors'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(64), unique=True, index=True)
password_hash = db.Column(db.String(128))
def __init__(self, **kwargs):
super(Tutor, self).__init__(**kwargs)
def __repr__(self):
return '<Student %r>' % self.id
Then I also have app/__init__.py with the following code:
from flask import Flask
from flask_bootstrap import Bootstrap
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
#from .models import User, Task, Project, UserProject
from config import config
bootstrap = Bootstrap()
db = SQLAlchemy()
migrate = Migrate()
def create_app(config_name='default'):
#print config_name.name
app = Flask(__name__)
app.config.from_object(config[config_name])
config[config_name].init_app(app)
bootstrap.init_app(app)
db.init_app(app)
migrate.init_app(app, db)
## Register the main blueprint for main app functionality
from .main import main as main_blueprint
app.register_blueprint(main_blueprint)
return app
and app.py:
import os
from app import create_app, db
from app.models import Tutor, Student
app = create_app('default')
@app.shell_context_processor
def make_shell_context():
return dict(db=db, Tutor=Tutor, Student=Student)
I can run flask db init with no problem and it creates the migrations directory and all necessary files with the following output:
Creating directory /Users/Jasmine/projects/flask/flask-tutoring/migrations ... done
Creating directory /Users/Jasmine/projects/flask/flask-tutoring/migrations/versions ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/script.py.mako ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/env.py ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/README ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/alembic.ini ... done
Please edit configuration/connection/logging settings in '/Users/Jasmine/projects/flask/flask-tutoring/migrations/alembic.ini' before proceeding.
but when I try and run flask db migrate alembic can't detect that I've got tables in app/models.py. I get the following output:
INFO [alembic.runtime.migration] Context impl SQLiteImpl.
INFO [alembic.runtime.migration] Will assume non-transactional DDL.
INFO [alembic.env] No changes in schema detected.
There is no migration script created, its as though models.py doesn't exist.
Apologies if this is a repeated question, but I can't find another example where its the first migration that fails and no migration script at all is created.
I've tried checking if there is already a table created somewhere by running db.drop_all() in the shell but that doesn't seem to be the problem.
UPDATE
I figured out a way to solve this on my own but would like a better understanding of why this worked.
I re-named app.py to flasktutor.py and re-ran export FLASK_APP='flasktutor.py'. Subsequently the migration worked perfectly.
Please could someone explain why when the file was called app.py and I used export FLASK_APP='app.py' the migration did not register changes to the schema.
