Entity relation diagrams generator

eralchemy2 generates Entity Relation (ER) diagram (like the one below) from databases or from SQLAlchemy models. Works with SQLAlchemy < 1.4 but also with versions greater than 1.4

Example

Example for NewsMeme

Quick Start

Install

To install eralchemy2, just do:

$ pip install eralchemy2

eralchemy2 requires GraphViz to generate the graphs and Python. Both are available for Windows, Mac and Linux.

Usage from Command Line

From a database

$ eralchemy2 -i sqlite:///relative/path/to/db.db -o erd_from_sqlite.pdf

The database is specified as a SQLAlchemy database url.

From a markdown file.

$ curl 'https://raw.githubusercontent.com/maurerle/eralchemy2/main/example/newsmeme.er' > markdown_file.er
$ eralchemy2 -i 'markdown_file.er' -o erd_from_markdown_file.pdf

From a Postgresql DB to a markdown file excluding tables named `temp` and `audit`

$ eralchemy2 -i 'postgresql+psycopg2://username:password@hostname:5432/databasename' -o filtered.er --exclude-tables temp audit

From a Postgresql DB to a markdown file excluding columns named `created_at` and `updated_at` from all tables

$ eralchemy2 -i 'postgresql+psycopg2://username:password@hostname:5432/databasename' -o filtered.er --exclude-columns created_at updated_at

From a Postgresql DB to a markdown file for the schema `schema`

$ eralchemy2 -i 'postgresql+psycopg2://username:password@hostname:5432/databasename' -s schema

Usage from Python

from eralchemy2 import render_er
## Draw from SQLAlchemy base
render_er(Base, 'erd_from_sqlalchemy.png')

## Draw from database
render_er("sqlite:///relative/path/to/db.db", 'erd_from_sqlite.png')

Architecture

Thanks to it's modular architecture, it can be connected to other ORMs/ODMs/OGMs/O*Ms.

Contribute

Every feedback is welcome on the GitHub issues.

To run the tests, use : $ py.test or $ tox. Some tests require a local postgres database with a schema named test in a database named test all owned by a user named eralchemy with a password of eralchemy. This can be easily set up using docker-compose with: docker-compose up -d.

All tested PR are welcome.

Notes

eralchemy2 is a fork of its predecessor ERAlchemy by @Alexis-benoist, which is not maintained anymore and does not work with SQLAlchemy > 1.4. If it is maintained again, I'd like to push the integrated changes upstream.

ERAlchemy was inspired by erd, though it is able to render the ER diagram directly from the database and not just only from the ER markup language.

Released under an Apache License 2.0

Initial Creator: Alexis Benoist Alexis_Benoist

sVathis/eralchemy2