Flask SQLAlchemy db.create_all() not creating database

问题

I can't seem to figure out why my call to db.create_all() is not working.

I have an app package with following init:

from flask import Flask
from config import config
from flask.ext.sqlalchemy import SQLAlchemy

# create the database object
db = SQLAlchemy()

# this function is the application factory
def create_app(environment):
    app = Flask(__name__)
    app.config.from_object(config[environment])

    db.init_app(app)

    from bp_root import bp_root
    from bp_aws import bp_aws

    app.register_blueprint(bp_root, url_prefix='/')
    app.register_blueprint(bp_aws, url_prefix='/aws')

    return app

Then I have models.py inside the app package:

from datetime import datetime
from . import db

class MyTestClass(db.Model):
    __tablename__ = 'mytesttable'
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(64), nullable=False, unique=True, index=True)
    username = db.Column(db.String(64), nullable=False, unique=True, index=True)
    is_admin = db.Column(db.Boolean)
    password_hash = db.Column(db.String(128))
    location = db.Column(db.String(64))
    member_since = db.Column(db.DateTime, default=datetime.utcnow)
    bio = db.Column(db.Text())

    def __init__(self, email, username):
        self.email = email
        self.username = username

    def __repr__(self):
        return '<User %r>' % self.username

app.config contains, among other things, the following:

'SQLALCHEMY_DATABASE_URL': 'sqlite:////Users/xxxxx/projects/yyyyy/data-dev.sqlite'

Then if I fire up my interactive shell, you can see objects exist appropriately and call to db.create_all() appears to work, but results in no database creation:

$ ./manage.py shell
>>> from app import db
>>> from app import models
>>> app
<Flask 'app'>
>>> db
<SQLAlchemy engine='sqlite://'>
>>> models
<module 'app.models' from '/Users/xxxxx/projects/yyyyy/app/models.py'>
>>> dir(models)
['MyTestClass', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'datetime', 'db']
>>> db.create_all()
>>>

Any thoughts on why the database isn't getting created?