[feat] Bail / Early Cancel Mode

[MentalGear]

It's not clear whether this library provides a bail / early cancel mode to throw if already one property fails to validate. This would greatly help server running costs. As typebox is really performance minded, this 'strict' mode with 'bail' would make a great addition. Thank you!

[sinclairzx81]

@MentalGear Hi,

Check

TypeBox will terminate on the first error with Check by default. Internally, this is done using chained logical expressions (A && B && C) where if A fails, condition B and C are not checked.

const A = () => { console.log('A'); return false } 
const B = () => { console.log('B'); return true } 
const C = () => { console.log('C'); return true } 

const R = A() && B() && C() // only A is printed

All checks are implemented using logical expressions like the above.

Errors

Unlike Check, TypeBox uses an iterator system for Errors. Because errors may need to be exhaustive, the Check logic is re-implemented for the Errors to "NOT use chained expressions" and to "NOT terminate on error". Instead the Errors function will yield at each failure case and continue....the caller receiving the errors can chose to yield only the first (terminate on error) or all (exhaustive checking)

const T = Type.Object({ ... })

const F = Value.Errors(T, { ... }).First()  // terminate at first error

const A = [...Value.Errors(T, { ... })]     // exhaustive errors

This means that there no need to implement a strict mode, as the caller can chose either first or exhaustive processing by receiving values of the iterator.

Usage

Putting it all together, the following implements a Parse function using both Check and Errors.

import { Type, Static, TSchema } from '@sinclair/typebox'
import { Value } from '@sinclair/typebox/value'

export function Parse<T extends TSchema>(schema: T, value: unknown): Static<T> {
  if(Value.Check(schema, value)) return value        // check and return
  const first = Value.Errors(schema, value).First()! // optionally gather diagnostics
  throw Error(first.message)                         // ... and throw
}

const A = Parse(Type.String(), 'hello')