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Simple entity relation (ER) diagrams generation

Project description

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ERAlchemy generates Entity Relation (ER) diagram (like the one below) from databases or from SQLAlchemy models.


Example for NewsMeme

Example for a graph

Example for NewsMeme

Quick Start

Install on a mac

The simplest way to install eralchemy on OSX is by using Homebrew

$ brew install eralchemy


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.

Usage from Command Line

From a database

$ eralchemy -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 '' >
$ eralchemy -i '' -o erd_from_markdown_file.pdf

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

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

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

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

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

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

Usage from Python

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')


Architecture schema

Architecture schema

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.

To run the tests, use : $ py.test. Some tests require a local postgres database with a schema named test in a database named test all owned by a user named postgres with a password of postgres.

All tested PR are welcome.


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

Creator: Alexis Benoist Alexis_Benoist

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