Sql – How to add new objects to FormAlchethe’s Grid

SQLAlchemy-Utils provides custom data types and various utility functions for SQLAlchemy. You can install the most recent official version using pip:

pip install sqlalchemy-utils

The database helpers include a create_database function:

from sqlalchemy import create_engine
from sqlalchemy_utils import database_exists, create_database

engine = create_engine("postgres://localhost/mydb")
if not database_exists(engine.url):
    create_database(engine.url)

print(database_exists(engine.url))

As per the requests to my initial question, I've taken my third edit and made it my answer. As I'm not sure of the proper protocols, I've left the third edit in place above. If you've already read EDIT3, then you've read what I have as an answer.

I've managed to spend a little more time on this. I've set up the project in the following way:

Databases
    __init__.py
    databases.py
    settings.py
    DB1
        __init__.py
        models.py
    ...
    DB3
        __init__.py
        models.py

At present, I have a tuple of databases that are 'installed' in the settings.py file. Each DB entry is specified in INSTALLED_DATABASES = ('DB1', ..., 'DB3'). As I complete more models, they get added to the list of tuples. This allows me to add or remove content as I go.

I have the engine and sessions setup inside the models.py file, and have the __init.py__ file for each database set to from models import *.

In the databases.py file I have the following

class Databases(object):
    def __init__(self):
        for database in INSTALLED_DATABASES:
            setattr(self, database, __import__(database))

I can now use these via:

from databases import Databases

db = Databases()

for qr in db.DB1.query(db.DB1.User):
    print qr.userid, qr.username

SQLAlchemy is allowing me to manually specify column names when defining the models, which is a huge bonus to the standardization I wanted.

I've got a lot of work ahead of me still. I would like to create objects that force model validation (ie, is a field present? does a non-present field have a default value? etc.) and better incorporate how this works with my IDE (it kind of doesn't at present). But I'm off to the right track. I figured I'd update this for anyone who might by chance be wondering how to do the same thing I was.

Sorry this has become so long!

Cheers!