the-flow-guard

Flow Guard

Flow Guard is a babel macro that adds a runtime guard for your flow types. This macro generates decoders based on your flow types and throws a runtime error if the unsafe data does not match. It is useful to type-check the boundaries of your application for incoming unsafe data (See decoders).

Example guard macro

// @flow
import guard from 'flow-guard/macro';
 
type Point = { x: number, y: number };
 
function handlePost(someUnsafeData: any): Point {
  return guard<Point>(someUnsafeData);
}

Example decoder macro

// @flow
import createDecoder from 'flow-guard/decoder.macro';
import { guard } from 'decoders';
 
type Point = { x: number, y: number };
 
const pointDecoder = createDecoder<Point>();
 
function handlePost(someUnsafeData: any): Point {
  return guard(pointDecoder)(someUnsafeData);
}

Installation

Requires babel 7.x

npm install --save-dev babel-plugin-macros
npm install --save-dev flow-guard

Edit .babelrc to include the macros plugin: 'macros'