Node-RED flow drawer

A library and CLI for drawning Node-RED flows from JSON files.

Table of contents

• Prerequisites
• JavaScript API
  • Installation
  • Usage
  • Settings
• CLI
  • Installation
  • Usage
  • Batch processing
  • Export data formats
• How to install external nodes
• Known issues
• Troubleshooting
• Credits
• License

Prerequisites

• Node.js 6+

JavaScript API

Installation

npm install node-red-flow-drawer --save

Usage

Source

// index.js
const fs = require("fs");
const FlowDrawer = require("node-red-flow-drawer");
 
const flows = [{"id":"bfc121b1.6847","type":"tab","label":"Flow 2","disabled":false,"info":""},{"id":"c1f897dd.90a048","type":"http in","z":"bfc121b1.6847","name":"","url":"/in","method":"get","upload":false,"swaggerDoc":"","x":200,"y":540,"wires":[["9b1c0d8f.216f2"]]},{"id":"9b1c0d8f.216f2","type":"http response","z":"bfc121b1.6847","name":"","statusCode":"200","headers":{},"x":500,"y":540,"wires":[]}];

// Optional settings (here are defaults)
const settings = {
    httpNodeRoot: "/",      // Root for http nodes
    userDir: process.cwd()  // A directory with extenal node installations
};

new FlowDrawer(flows, settings)
    .draw("svg")
    .then((images) => {
        for (let image of images) {
            let [, data] = image.split("base64,");
            fs.writeFileSync("output.svg", new Buffer(data, "base64"));
        }
});

Running

node index.js

Output

Settings

• httpNodeRoot - root for http nodes
• userDir - a directory with external node installations

CLI

Installation

npm install -g node-red-flow-drawer

Usage

flow-drawer -h

Usage: flow-drawer [options] <inputFileOrDir> [outputDir]

Options:
  -v, --version          output the version number
  -f, --format <format>  export data format (html, json or img) (default: "html")
  -n, --nodes <dir>      path to a directory with installed as npm packages external nodes (CWD by default)
  -s, --stdout           print results to the stdout (only for file input and html/json output)
  -h, --help             output usage information

Batch processing

There are two options for input data:

• file
• directory

In the second case CLI searches for all files with .json extension in the directory tree starting from the input folder, tries to draw flows from that files and saves drawnings to the CWD or to the outputDir (if provided).

Export data formats

CLI supports three kinds of export data format:

• html - all flows save to a single HTML file (useful for previewing)
• json - all flows save to a single JSON file (with JSON array inside)
• img - each flow saves to a separate SVG file

Ouputs save to the outputDir (if provided) or to the CWD and name after the input file.

You can use --stdout option (only for html and json formats) to print results to the stdout instead of saving to files.

How to install external nodes

In order to install an external node, you need to install its npm package to a directory and provide the path to the directory as userDir setting in JavaScript API or as --nodes option for CLI.

Known issues:

• It's not possible to use SVG icons for nodes and to save flows as PNG on Windows (Automattic/node-canvas#1211)
• Exported images use another font

Troubleshooting

The library depends on node-canvas library. That's why you can face some issues during installation of the library in case if there are no prebuilt binaries for your system. In this case look at Compiling section of node-canvas documentation https://github.com/Automattic/node-canvas#compiling.

Nodejs 8.9.4

We found this error

node: symbol lookup error: /xxxxx/node-red-flow-drawer/node_modules/canvas/build/Release/canvas.node: undefined symbol: _ZN2v87Isolate19CheckMemoryPressureEv

Solution update to 8.12.0

Credits

Based on Node-RED 0.19.4.

License

MIT