Loopback UML Generator

I work in a company where we use Loopback for most of our Javascript projects. I realise that there was a gap between production code and architecture documents.

Because keeping diagrams up-to-date can be a time consuming task, I started working on a Node.js module that will generate the UML class diagram using the famous PlantUML Java library.

Installation

The library is available on this NPM repository

npm i -g loopback-uml-generator

The module will be installed globally.

You also need to download the PlantUML jar executable on your machine.

Then, just set the environment variables PLANTUML_JAR as the path of the executable.

Example: (MacOS / Linux)

export PLANTUML_JAR="~/Documents/plantuml.jar"

Usage

Once installed, just navigate into your Loopback project, and type:

lbUML <the-name-of-output-files>

The name argument is optional, if you don't set it, the module will use the app name and its version to generate the files (based on your package.json file).

Two files will be created at the root of your project:

• *.txt, the PlantUML description file
• *.png, the generated UML class diagram image file

Example

Here is a quick example that shows a basic UML class diagram:

Execution

Loopback-UML-Generator started...

 - PlantUML description file will be saved as UML-Generator-lb-car-1.0.0.txt
 - PlantUML image file will be saved as UML-Generator-lb-car-1.0.0.png
 - PlantUML jar used: ~/Documents/plantuml.jar
 ✓ Discovered 4 JSON model(s) in this project
 ♥ PlantUML started, please wait a few seconds...
 ✓ Done! Bye ♥

Result

You might want to customise the diagram's style (colors, and so on). Just edit the generated text diagram file, with some properties, such as skinparam monochrome, then execute the PlantUML jar file and you're good to go.

How it works

Based on files such as package.json and server/model-config.json, the module will scan for any JSON file present in the directories listed in _meta/sources property. Required fields and objects are extracted after and a formatter will create the UML description file. That's not rocket science :)

Limitations

Currently, the module supports the following Loopback's objects:

• classes
• properties
• remote-methods
• relations

Please note that for the relations object, only hasOne, hasMany, and belongsTo types are supported.

This module is still a demo, so feel free to contribuate or report any issue! Cheers ♥