Nedgeva / ts-io-diffs

ts-io-diffs

Description: TS-IO Diffs generates io-ts codecs and produces various utils for typesafe diff checking. It heavily relies on ts-to-io codebase and uses fast-json-patch for diff building.

How it's works

Given two objects (POJOs) with same type T, generate utils which allow you to check for diffs between them in (almost) typesafe manner.

Installation

git clone
yarn
yarn build
node .\cli.js --follow-imports path/to/your/file.ts

Example

Let's assume that you have some model of following shape:

import { Option } from 'fp-ts/lib/Option';
type Test = {
	a: string;
	b: number;
	c: Option<{
		d: boolean;
		e: {
			f: string;
		};
	}>;
	g: string;
};

and you want to get diff between two objects of abovementioned type:

const prevTest: Test = { a: 'foo', b: 777, c: some({ d: true, e: { f: 'azaza' } }), g: 'lol' };
const currentTest: Test = { a: 'bar', b: 777, c: some({ d: false, e: { f: 'azaz' } }), g: 'lol' };

then you can expect following utils to be generated:

const diffPathsForTest = getPathsOfChangedValues(Test.asEncoder(), prevTest, currentTest);
const lookupForChangedPathsInTest = checkIfValueChangedInRootPath<t.OutputOf<typeof Test>>(diffPathsForTest);
const isaInTestChanged = lookupForChangedPathsInTest(['a']);
const isbInTestChanged = lookupForChangedPathsInTest(['b']);
const iscInTestChanged = lookupForChangedPathsInTest(['c']);
const iscdInTestChanged = lookupForChangedPathsInTest(['c', 'd']);
const isceInTestChanged = lookupForChangedPathsInTest(['c', 'e']);
const iscefInTestChanged = lookupForChangedPathsInTest(['c', 'e', 'f']);
const isgInTestChanged = lookupForChangedPathsInTest(['g']);

or alternatively get utils like this:

const diffPathsForTest = getPatchesOfChangedValues(Test.asEncoder(), prevTest, currentTest);
const lookupForChangedPathsInTest = getChangeTypeOfChangedValueInPath<t.OutputOf<typeof Test>>(diffPathsForTest);
const getChangeTypeOfaInTest = lookupForChangedPathsInTest(['a']);
const getChangeTypeOfbInTest = lookupForChangedPathsInTest(['b']);
const getChangeTypeOfcInTest = lookupForChangedPathsInTest(['c']);
const getChangeTypeOfcdInTest = lookupForChangedPathsInTest(['c', 'd']);
const getChangeTypeOfceInTest = lookupForChangedPathsInTest(['c', 'e']);
const getChangeTypeOfcefInTest = lookupForChangedPathsInTest(['c', 'e', 'f']);
const getChangeTypeOfgInTest = lookupForChangedPathsInTest(['g']);

TODO

Add detailed description of diff checking mechanism.