mol_data_all

$mol_data

Defines static typed DTO with strict runtime validation and user friendly error messages like:

["friends"][0]["phone"] undefined is not any of variants
undefined is not a string
undefined is not a number

Usage examples

Entities

// Base Type
const PersonDTO = $mol_data_record({
	name : $mol_data_string ,
	age : $mol_data_optional( $mol_data_integer ) ,
	birthday : $mol_data_pipe( $mol_data_string , $mol_time_moment ) ,
})

// Derived Type
const UserDTO = $mol_data_record({
	... PersonDTO.config,
	phone: $mol_data_variant( $mol_data_string , $mol_data_integer ),
	mail: $mol_data_email,
})

// Ensure this is a User
const jin = UserDTO({
	name : 'Jin' ,
	age : 33 ,
	birthday : '1984-08-04T12:00:00Z' ,
	phone : [phone],
	mail : '[e-mail]' ,
})

// typeof jin === {
// 	readonly name: string;
// 	readonly age?: number | undefined;
// 	readonly birthday: $mol_time_moment;
// 	readonly phone: string | number;
// 	readonly mail: string;
// }

// Allow only Users
function printName( user : typeof UserDTO.Value ) {
	console.log( user.name )
}

printName( jin )

// Wrong json from server
const json = {
	name : 'Jin' ,
	age : 33 ,
	birthday : '1984-08-04T12:00:00Z' ,
	phone : [phone],
	mail : '</script>' , // !
} as any

// Runtime error: ["mail"] </script> is not a /.+@.+/
printName( UserDTO( json ) )

Units

const Weight = $mol_data_nominal({ Weight : $mol_data_integer })
const Length = $mol_data_nominal({ Length : $mol_data_integer })

let len = Length(10)
len = Length(20) // Validate
len = 20 as typeof Length.Value // Cast

len = 20 // Compile time error
len = Weight(20) // Compile time error
len = Length( 20.1 ) // Run time error

(De)Serialization

const Duration = $mol_data_pipe(
	$mol_data_variant(
		$mol_data_string ,
		$mol_data_integer ,
	) ,
	$mol_time_duration ,
)

JSON.stringify( Duration( 'P1D' ) ) // "P1DT"
JSON.stringify( Duration( 1000 ) ) // "PT1S"

Usage from NPM

npm install mol_data_all

import {
  $mol_data_nominal as Nominal,
  $mol_data_integer as Integer,
} from "mol_data_all"

const Int = Nominal({ Int: Integer })

const i = Int(1)
const j: typeof Int.Value = Int( i + 1 )

More complex example.

Similar projects

• gcanti/io-ts - Runtime type system for IO decoding/encoding
• pelotom/runtypes - Runtime validation for static types
• vriad/zod - TypeScript-first schema validation with static type inference
• ianstormtaylor/superstruct - A simple and composable way to validate data in JavaScript (and TypeScript).