flask sqlalchemy example around existing database

Question

Problem: there needs to be full working example of auto-mapping sqlalchemy to an existing database in an app with multiple binds.

I want to bind to two databases and have one auto-map the tables. I need to do this because i don't have control over one DB, thus would have to constantly re-write my models and might delete new tables every time i migrate.

I love the answers given here, but i can't seem to make it work in Flask (I am able to use the sqlalchemy only to query as per the example).

The model.py I set up from the example above results in

EDIT I pulled the line

 db.Model.metadata.reflect[db.engine]

from another post, and it should be db.Model.metadata.reflect(db.engine) very simple solution

here is my model.py

from app import db
from sqlalchemy.orm import relationship

db.Model.metadata.reflect[db.engine]#change to (db.engine)

class Buildings(db.Model):
    __table__ = db.Model.metadata.tables['test']
    __bind_key__ = 'chet'
    def __repr__(self):
        return self.test1

.... other models from sqlalchemy uri here...

i get this

>>> from app import db, models
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "app/__init__.py", line 69, in <module>
    from app import views, models
  File "app/views.py", line 1, in <module>
    from app import app,models, db
  File "app/models.py", line 163, in <module>
    db.Model.metadata.reflect[db.engine]
TypeError: 'instancemethod' object has no attribute '__getitem__'

Here's my config.py

SQLALCHEMY_DATABASE_URI = 'postgresql://chet@localhost/ubuntuweb'

SQLALCHEMY_BINDS = {
    'chet':        'postgresql://chet@localhost/warehouse',
 }

here's my init.py file

from flask import Flask
from flask_bootstrap import Bootstrap
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.admin import Admin, BaseView, expose
from flask.ext.script import Manager
from flask.ext.migrate import Migrate, MigrateCommand
from flask.ext.login import LoginManager, UserMixin, login_required

app = Flask(__name__)

app.config['UPLOAD_FOLDER'] = 'app/static'
app.config.from_object('config')
db = SQLAlchemy(app)
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)

Bootstrap(app)

from app import views, models
admin = Admin(app)

Adam Smith · Accepted Answer · 2015-10-20 23:55:42Z

7

Your code has

db.Model.metadata.reflect[db.engine]

When it should be

db.Model.metadata.reflect(db.engine)  # parens not brackets

This should have been pretty obvious from the stack trace....

answered Oct 20, 2015 at 23:55

Adam Smith

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5 Comments

Chet Meinzer Over a year ago

Thanks for your help. I pulled the hard brackets out of the link in my post and part of my question is why the answer has brackets. It was from stackoverflow.com/questions/17652937/… "bind the declarative base to an engine: db.Model.metadata.reflect[db.engine]"

Adam Smith Over a year ago

@ChetMeinzer because the answer is wrong. I'll edit to correct it now.

Adam Smith Over a year ago

@ChetMeinzer (you'll notice that the top-voted and accepted answer has the correct syntax! :D)

Chet Meinzer Over a year ago

Ever look for something and it's right under your nose. spent hours confused-ready to get back to work. thanks again.

Adam Smith Over a year ago

@ChetMeinzer glad I could help! :)

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