This is a tool that reads the structure of an existing database and generates the appropriate SQLAlchemy model code, using the declarative style if possible.

This tool was written as a replacement for sqlautocode, which was suffering from several issues (including, but not limited to, incompatibility with Python 3 and the latest SQLAlchemy version).

Features

• Supports SQLAlchemy 0.6.x - 1.0.x
• Produces declarative code that almost looks like it was hand written
• Produces PEP 8 compliant code
• Accurately determines relationships, including many-to-many, one-to-one
• Automatically detects joined table inheritance
• Excellent test coverage

Usage instructions

Installation

To install, do:

pip install sqlacodegen

or, failing that:

easy_install sqlacodegen

Example usage

At the minimum, you have to give sqlacodegen a database URL. The URL is passed directly to SQLAlchemy's create_engine() method so please refer to SQLAlchemy's documentation for instructions on how to construct a proper URL.

Examples:

sqlacodegen postgresql:///some_local_db
sqlacodegen mysql+oursql://user:password@localhost/dbname
sqlacodegen sqlite:///database.db

To see the full list of options:

sqlacodegen --help

Model class naming logic

The table name (which is assumed to be in English) is converted to singular form using the "inflect" library. Then, every underscore is removed while transforming the next letter to upper case. For example, sales_invoices becomes SalesInvoice.

Relationship detection logic

Relationships are detected based on existing foreign key constraints as follows:

• many-to-one: a foreign key constraint exists on the table
• one-to-one: same as many-to-one, but a unique constraint exists on the column(s) involved
• many-to-many: an association table is found to exist between two tables

A table is considered an association table if it satisfies all of the following conditions:

1. has exactly two foreign key constraints
2. all its columns are involved in said constraints

Relationship naming logic

Relationships are typically named based on the opposite class name. For example, if an Employee class has a column named employer which has a foreign key to Company.id, the relationship is named company.

A special case for single column many-to-one and one-to-one relationships, however, is if the column is named like employer_id. Then the relationship is named employer due to that _id suffix.

If more than one relationship would be created with the same name, the latter ones are appended numeric suffixes, starting from 1.

Source code

The source can be browsed at GitHub.

Reporting bugs

An issue tracker is provided by github.com.

Getting help

If you have problems or other questions, you can either:

• Ask on the SQLAlchemy Google group, or
• Ask on the #sqlalchemy channel on Freenode IRC