graphviz-erd

Draw Entity Relationship Diagrams (ERD) with python and graphviz.

This code is built on top of the graphviz python package and provides methods to facilitate the declaration of blocks commonly used in ERD such as entities and attributes.

Example

We can draw diagrams like

using the code:

    gr = graphviz.Graph("ER", filename="erd", engine="dot", format="png")
    obj = ERD(gr)

    # node name and node label
    obj.entity("entity1", "entity 1")
    # the label is optional as it is in graphviz
    obj.attribute("attr")
    # new lines using the html notation
    obj.multivalue("multi", "multivalued<BR/>attribute")
    obj.key("key", "key attribute")
    obj.derived("derived")
    obj.weak_key("weak")

    obj.associative_entity("assoc", "associative<BR/>entity")

    obj.weak_entity("entity2", "weak entity 2")

    # draw relation between entities
    obj.relation("relationship", "entity1", "entity2", "(1,2)", "(2, 1)", "yes")

    # connect the attributes
    obj.gr.edges(
        [
            ("entity1", "attr"),
            ("entity1", "multi"),
            ("entity1", "key"),
            ("entity1", "weak"),
            ("entity1", "derived"),
        ]
    )

    obj.gr.view()

Instructions (Development)

Assuming a linux environment (Ubuntu), to develop inside a virtual environment using git hooks:

python3 -m venv .venv
source .venv/bin/activate
pip install wheel
pip install -r requirements.txt
pre-commit install