Django ERD Generator is a command-line tool designed to generate Entity-Relationship Diagrams (ERDs) from Django models. It supports multiple output formats, making it easy to visualise database relationships in different diagramming tools. The generator extracts model definitions, fields, and relationships, converting them into structured representations suitable for use with Mermaid.js, PlantUML, and dbdiagram.io. This tool is useful for understanding database structures, documenting data models, and sharing visual representations with team members.

Supported dialects:

• Mermaid.js
• PlantUML
• dbdiagram.io

Quickstart

To generate an Entity-Relationship Diagram (ERD) in the desired syntax, use the generate_erd command:

python manage.py generate_erd [-h] [-a APPS] [-d DIALECT] [-o OUTPUT]

Options

Option	Description
-h, --help	Show the help message and exit.
-a APPS, --apps APPS	Specify the apps to include in the ERD, separated by commas (e.g., "shopping,polls"). If omitted, all apps will be included.
-d DIALECT, --dialect DIALECT	Set the output format. Supported dialects: mermaid, plantuml, dbdiagram.
-o OUTPUT, --output OUTPUT	Define the output file path. If omitted, the output is printed to the console.

Examples

Generate an ERD for all apps in Mermaid format and print to console:

python manage.py generate_erd -d mermaid

Generate an ERD for shopping and polls apps in PlantUML format and save to erd.puml:

python manage.py generate_erd -a shopping,polls -d plantuml -o erd.puml

Example Output

from django.db import models


class Customer(models.Model):
    first_name = models.TextField()
    last_name = models.TextField()
    date_of_birth = models.DateField()


class Product(models.Model):
    sku = models.TextField()
    product_name = models.TextField()
    product_code = models.TextField()
    quantity = models.IntegerField()
    price = models.DecimalField(max_digits=16, decimal_places=2)
    regions = models.ManyToManyField("Region")


class Order(models.Model):
    customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    quantity = models.IntegerField()
    order_total = models.DecimalField(max_digits=16, decimal_places=2)


class Region(models.Model):
    name = models.TextField()
    label = models.TextField()

Mermaid.js

Code Output

erDiagram
Customer {
  integer id pk
  text first_name
  text last_name
}
Product {
  integer id pk
  text sku
  text product_name
  text product_code
  integer quantity
  decimal price
}
Order {
  integer id pk
  integer customer_id
  integer product_id
  integer quantity
  decimal order_total
}
Region {
  integer id pk
  text name
  text label
}
Product }|--|{ Region: ""
Order }|--|| Customer: ""
Order }|--|| Product: ""

Rendered Example

PlantUML

Code Output

@startuml

entity Customer {
  *id: integer
  first_name: text
  last_name: text
}
entity Product {
  *id: integer
  sku: text
  product_name: text
  product_code: text
  quantity: integer
  price: decimal
}
entity Order {
  *id: integer
  customer_id: integer
  product_id: integer
  quantity: integer
  order_total: decimal
}
entity Region {
  *id: integer
  name: text
  label: text
}
Product }|--|{ Region
Order }|--|| Customer
Order }|--|| Product

@enduml

Rendered Example

dbdiagram.io

Code Output

Table Customer {
  id "integer" [primary key]
  first_name "text"
  last_name "text"
}
Table Product {
  id "integer" [primary key]
  sku "text"
  product_name "text"
  product_code "text"
  quantity "integer"
  price "decimal"
}
Table Order {
  id "integer" [primary key]
  customer_id "integer"
  product_id "integer"
  quantity "integer"
  order_total "decimal"
}
Table Region {
  id "integer" [primary key]
  name "text"
  label "text"
}
Ref: Product.regions <> Region.id
Ref: Order.customer_id > Customer.id
Ref: Order.product_id > Product.id

Rendered Example

Supported Versions

This project is tested against the following versions:

• Python: 3.8, 3.9, 3.10, 3.11, 3.12
• Django: Latest compatible version based on tox dependencies

Ensure you have one of the supported Python versions installed before running tests. You can check your Python version with:

python --version

For testing, tox will automatically create isolated environments for each supported Python version.