sqlalchemy-dataflex 0.1.2

A SQLAlchemy dialect for DataFlex flat-file databases.

SQLAlchemy-DataFlex

A SQLAlchemy dialect for the FlexODBC driver

Objectives

This dialect is mainly intended to offer an easy way to access the DataFlex flat-file databases of older or EOL'd application-specific softwares. It is designed for use with the ODBC driver available from FlexQuarters

Pre-requisites

• The FlexODBC driver from FlexQuarters. The library was written and tested against v3, but it should work with v4 as well. The library has been re-written from the ground up and tested to work against the latest available version of FlexODBC (4.0.27.2).

• 32-bit Python. Neither of the available FlexODBC driver versions support or come in a 64-bit version.

Co-requisites

This dialect requires SQLAlchemy and pyodbc. They are both specified as requirements so pip will install them if they are not already in place. To install separately, just:

pip install -U SQLAlchemy pyodbc

Installation

PyPI-published version:

pip install -U sqlalchemy-dataflex

Absolute bleeding-edge (probably buggy):

pip install -U git+https://github.com/the-wondersmith/sqlalchemy-dataflex

Getting Started

Create an ODBC DSN (Data Source Name) that points to the directory containing your DataFlex FILELIST.cfg and .DAT table.

Tip: For best results, be sure to select the 4-digit date option and the . option for decimals

Then, in your Python app, you can connect to the database via:

from sqlalchemy_dataflex import *
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker


db = create_engine("dataflex+pyodbc://@your_dsn", echo=False)
super_session = sessionmaker(bind=db)
super_session.configure(autoflush=True, autocommit=True, expire_on_commit=True)
session = super_session()

NOTE: It is highly recommended that you use the datatype classes from the package itself in place of the ones that are usually imported from SQLAlchemy. The testing suite doesn't use the SQLAlchemy type classes, so any issues that might arise from their use with the dialect won't be caught by the tests.

The SQLAlchemy Project

SQLAlchemy-DataFlex is based on SQLAlchemy-access, which is part of the [SQLAlchemy Project] (https://www.sqlalchemy.org) and tries to adhere to the same standards and conventions as the core project.

At the time of this writing, it's unlikely that SQLAlchemy-DataFlex actually does comply with the aforementioned standards and conventions. That will be rectified (if and when) in a future release.

Development / Bug reporting / Pull requests

SQLAlchemy maintains a Community Guide detailing guidelines on coding and participating in that project.

While I'm aware that this project could desperately use the participation of anyone else who actually knows what they're doing, DataFlex and the FlexODBC driver are so esoteric and obscure (at the time of this writing) that I don't reasonably expect anyone to actually want to. If I am mistaken in that belief, please God submit a pull request.

This library technically works, but it isn't feature-complete so to speak. The FlexODBC driver only supports a very limited subset of SQL commands and queries, and doesn't always respond to pyodbc's get_info() inquiries the way that pyodbc is expecting. You can see the complete list of the way it responds to all of the available pyodbc get_info() inquiries here. If you are interested in which features are currently lacking or absent in the dialect, see the notes and comments littered throughout the testing suite here.

License

This library is derived almost in its entirety from the SQLAlchemy-Access library written by Gord Thompson. As such, and given that SQLAlchemy-access is distributed under the MIT license, this library is subject to the same licensure and grant of rights as its parent works SQLAlchemy and SQLAlchemy-Access.