eralchemy 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 for NewsMeme

To install eralchemy, just do:

$ pip install eralchemy

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

For Debian based systems, run:

$ apt install graphviz libgraphviz-dev

before installing eralchemy.

There is also a packaged version in conda-forge, which directly installs the dependencies:

$ conda install -c conda-forge eralchemy

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

The database is specified as a SQLAlchemy database url.

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

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

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

$ eralchemy -i 'postgresql+psycopg2://username:password@hostname:5432/databasename' -s "schema1, schema2"

$ eralchemy -i 'markdown_file.er' -o erd_from_markdown_file.md -m mermaid_er

from eralchemy 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')

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

Every feedback is welcome on the GitHub issues.

Install the development dependencies using

$ pip install -e .[ci,dev]

Make sure to run the pre-commit to fix formatting

$ pre-commit run --all

All tested PR are welcome.

This project uses the pytest test suite. To run the tests, use : $ pytest or $ tox.

Some tests require having a local PostgreSQL database with a schema named test in a database named test all owned by a user named eralchemy with a password of eralchemy. If docker compose is available, one can use docker compose up -d for this purpose. You can deselect the tests which require a PostgreSQL database using:

$ pytest -m "not external_db"

$ rm -r dist && python -m build && python3 -m twine upload --repository pypi dist/*

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