Pydantic Mermaid

To convert Pydantic models to Mermaid charts, you can use the pydantic-mermaid library. This library allows you to generate Mermaid charts from your Pydantic models. Here are the steps to install and use pydantic-mermaid:

If you are using pydantic 2, please visit https://github.com/EricWebsmith/pydantic-2-mermaid

Use in terminal

Install the pydantic-mermaid library using pip:

pip install pydantic-mermaid

Use command line

pydantic-mermaid --module models.py --output models.md

You can run the following comamand get help for the command.

pydantic-mermaid --help

Use in code

1. Import your Pydantic models into your Python script.
2. Create an instance of the MermaidGenerator class from the pydantic-mermaid module and pass in your Pydantic models as arguments.

from pydantic_mermaid import MermaidGenerator

import my_module

generator = MermaidGenerator(my_module)

3. Call the generate_chart() method of the MermaidGenerator instance to generate the Mermaid chart.

chart = generator.generate_chart()

4. Use the chart variable to display or save the Mermaid chart.

print(chart)

This will print the Mermaid chart as a string. You can also save the chart to a file by writing the chart string to a file:

with open("chart.mmd", "w") as f:
    f.write(chart)

This will save the Mermaid chart to a file called chart.mmd. You can then use a tool like the Mermaid Live Editor to visualize and edit the chart.

examples

Inheritance:

classDiagram
    class Animal {
    }

    class Fish {
        gill: str
    }

    class Beast {
        lags: int
    }

    class Bird {
        winds: int
    }

    class Dog {
    }

    class Cat {
    }

    class Salmon {
    }

    class Eagle {
    }


    Animal <|-- Fish
    Animal <|-- Bird
    Animal <|-- Beast
    Beast <|-- Cat
    Beast <|-- Dog
    Fish <|-- Salmon
    Bird <|-- Eagle

dependencies:

Administrative Divisions of the United States of America

classDiagram
    class Municipality {
        name: str
        population: int
    }

    class MinorCivilDivision {
        name: str
        population: int
    }

    class County {
        name: str
        population: int
        municipalities: list[Municipality]
        minor_civil_divisions: list[MinorCivilDivision]
    }

    class CountyEquivalant {
        name: str
        population: int
    }

    class State {
        name: str
        population: int
        counties: list[County]
        county_equivalants: list[CountyEquivalant]
    }

    class FederalDistrict {
        name: str
        population: int
    }

    class InhabitedTerritory {
        name: str
        population: int
    }

    class HabitedTerritory {
        name: str
        population: int
    }

    class Federal {
        name: str
        population: int
        federal_distric: FederalDistrict
        states: list[State]
        Inhabited_territories: list[InhabitedTerritory]
        Habited_territories: list[HabitedTerritory]
    }


    County ..> MinorCivilDivision
    County ..> Municipality
    State ..> CountyEquivalant
    State ..> County
    Federal ..> InhabitedTerritory
    Federal ..> HabitedTerritory
    Federal ..> State
    Federal ..> FederalDistrict

For details, check examples/ folder.