Tcomb-validation-middleware NPM

Tcomb Validation Middleware

Express Middleware that performs runtime type checking of objects. It is primerily meant for type checking in development.

Build

Tests

Installation

npm i tcomb-validation-middleware

Usage

Use the library tcomb to define the model of the data structure

const t = require('tcomb');

const test = t.struct({
  test: t.String,
  bool: t.Boolean,
});

module.exports = {
  test,
};

Then add as middleware to the route of the endpoint

const t = require('tcomb-validation-middleware');

... //Express setup stuff

app.post('/test', t(test), (req, res) => {
  res.send({ message: 'schema was obviously valid' });
});

The module also accepts an options object like so

t(test,{ active: true, verboseErrors: false })

Tests

To run the tests do

npm test

Performance

Applying strict type validation to your server will decrease it's performance slightly under heavy loads but the tradeoff of very usefull error messages can make it worth it. If in production in an environment where you control the client it's very easy to reuse your tcomb schemas. This allows you to move the validation client side without much development overhead.

The results in the table below are generated using artillery.

First Header	Scenarios launched	Scenarios completed	Requests completed	RPS sent	Request latency	min	max	median	p95	p99	Scenario duration	min	max	median	p95	p99
Enabled	1000	1000	20000	970.87	->	0.3	41.4	0.4	2.8	11.7	->	14.5	447.2	18.7	98	384.6
Disabled	1000	1000	20000	970.4	->	0.2	24.2	0.4	1.6	3.5	->	11	124.8	16.6	48.6	108.1

If you would like to verify them clone the module from git then run the following commands.

cd express-tcomb-validation-middleware
npm install
node ./test/lib/index.js

Then in another window run

npm install -g artillery
artillery quick --count 1000 -n 20 http://localhost:4444/test/on/test/hi
artillery quick --count 1000 -n 20 http://localhost:4444/test/off/test/hi