@radixdlt/data-formats

Usage

JSON Decoding

Examples

Without dependencies, using provided taggedStringDecoder:

import { JSONDecoding, taggedStringDecoder } from '@radixdlt/data-formats'

const strTagDecoder = taggedStringDecoder(':str:')((value) => ok(value))

const { fromJSON } = JSONDecoding.withDecoders(strTagDecoder).create()

fromJSON(':str:xyz') // Ok('xyz')

An object with dependencies:

import { JSONDecoding, taggedStringDecoder } from '@radixdlt/data-formats'
import { ok } from 'neverthrow'

const strTagDecoder = taggedStringDecoder(':str:')((value) => ok(value))

const Object1 = {
    ...JSONDecoding.withDecoders(strTagDecoder).create()
}

const tstTagDecoder = taggedStringDecoder(':tst:')((value) => ok(value))

const { fromJSON } = JSONDecoding
	.withDependencies(Object1)
	.withDecoders(testTagDecoder)
	.create()

fromJSON({
    a: ':str:foo',
    b: ':tst:bar'
}) // ok({ a: 'foo', b: 'bar' })

JSON decoding takes an object and applies decoders to each key-value pair. taggedObjectDecoder and taggedStringDecoder are provided, but you can easily define a new decoder. Here is how taggedStringDecoder is defined:

import { decoder } from '@radixdlt/data-formats'

export const taggedStringDecoder = (tag: string) => <T>(
	algorithm: (value: string) => Result<T, Error>,
): Decoder =>
	decoder<T>((value) =>
		isString(value) && `:${value.split(':')[1]}:` === tag
			? algorithm(value.slice(tag.length))
			: undefined,
	)

A decoder should supply a function that defines how the decoding should be applied. First it should do some validation logic (does this decoder apply to this value?), in this case checking if the value is a string and if has a matching tag. Then, apply some algorithm function, which is the actual decoding (create an instance of some object). If the validation fails, the decoder has to return undefined.