Can the output of `.json` be used to construct an arktype schema?

For example:

const booleanJson = type.boolean.json
console.log(booleanJson)
// => [ { unit: false }, { unit: true } ]

// what I'm after is an API that let's me do this:

type([ { unit: false }, { unit: true }])

// or more directly:
type(type.boolean.json)

const booleanJson = type.boolean.json
console.log(booleanJson)
// => [ { unit: false }, { unit: true } ]

// what I'm after is an API that let's me do this:

type([ { unit: false }, { unit: true }])

// or more directly:
type(type.boolean.json)

22 Replies

ssalbdivad•2d ago

type.schema(type.boolean.json) although it will fail for non-serializable constraints You also probably have to cast the input for now type.schema(type.boolean.json as never) or something since it's not officially supported because of the serializability issue

ssalbdivad•2d ago

Relevant: https://github.com/arktypeio/arktype/discussions/1377

GitHub

How to construct a new Type from an exiting Type's internal JSON re...

Related to #1225 & #818 Type.toJSON()/.json return an internal representation of that type, parsed and reorganized from what is passed to `type(): const device = type({ platform: "'and...

ahrjarrettOP•2d ago

awesome -- thank you!

ahrjarrettOP•2d ago

i've got a possible bug -- going to open an issue for it, but wanted to double check here to make sure it isn't just user error on my part https://stackblitz.com/edit/vitest-dev-vitest-ddhwwn9j?file=test%2Frepro.test.ts

andrew jarrett

StackBlitz

arktype union possible bug repro - StackBlitz

Run official live example code for Vitest Basic, created by Vitest Dev on StackBlitz

ahrjarrettOP•2d ago

tl;dr

const schema1 = type.Record(
  "string", 
  type("3 <= null[] <= 10").or('false').or([type.undefined])
)

const schema2 = type.Record(
  "string",
  type('null[]').or('false').or([type.undefined]) 
)

schema1({ a: false }) // => { a: false }
schema2({ a: false }) // => ArkErrors[]

const schema1 = type.Record(
  "string", 
  type("3 <= null[] <= 10").or('false').or([type.undefined])
)

const schema2 = type.Record(
  "string",
  type('null[]').or('false').or([type.undefined]) 
)

schema1({ a: false }) // => { a: false }
schema2({ a: false }) // => ArkErrors[]

not sure why the range constraint would change the behavior there. also not sure why, but the [type.undefined] is necessary too this doesn't come from an actual use case, this was a generated schema

ssalbdivad•2d ago

Yeah that does look like a bug

ahrjarrettOP•2d ago

cool. i'll raise the issue. unless you'd prefer i put it on reddit?? hah 😭 that shit

ssalbdivad•2d ago

It probably has something to do with discrimination

ahrjarrettOP•2d ago

cool. thanks for everything you do!

ssalbdivad•2d ago

I will probably see if I can fix this now, hopefully relatively simple 🙏

ahrjarrettOP•2d ago

oh wow, i haven't seen the playground until now. nice!

ssalbdivad•2d ago

Ahh interesting, I see the issue

{
  kind: 'unit',
  path: [ '0' ],
  cases: {
    undefined: [
      {
        sequence: {...},
          proto: 'Array',
          exactLength: 1
        },
      {
        sequence: {...},
          proto: 'Array'
        }
      ],
      null: { sequence: { unit: null }, proto: 'Array' },
      default: { unit: false }
    }
  }

{
  kind: 'unit',
  path: [ '0' ],
  cases: {
    undefined: [
      {
        sequence: {...},
          proto: 'Array',
          exactLength: 1
        },
      {
        sequence: {...},
          proto: 'Array'
        }
      ],
      null: { sequence: { unit: null }, proto: 'Array' },
      default: { unit: false }
    }
  }

This is the discriminant The problem is that in this case, default is equivalent to undefined, so the default case is never hit

ahrjarrettOP•2d ago

https://github.com/arktypeio/arktype/issues/1440 default means default discriminant? not like, default value?

ssalbdivad•2d ago

This whole thing represents the way the discrimination works i.e. check the value at path [0], then depending on which case it ===, apply the remaining checks But the combination of the array + tuple leads to a bad result here

ahrjarrettOP•2d ago

gotcha. yeah it'd be a pretty strange schema to write by hand

ssalbdivad•2d ago

Definitely a good case to fix though! Glad you caught it Oh the ...s make the example a bit more confusing

ssalbdivad•2d ago

This is the full case. I'm glad it gets the possibility of null[] having the value undefined

ssalbdivad•2d ago

So the only problem is that default also needs to be grouped with undefined here

ahrjarrettOP•2d ago

tbh, i'm not sure i understand hah. specifically i think the { undefined: [{ sequence: { prefix: [{ unit: 'undefined' }] } }] } bit is confusing me

ssalbdivad•2d ago

It's saying if the value at 0 is undefined, , check that the root value is either [undefined] or a null[] (int his case it would have to be []) But actually this discriminant is degenerate because once you include false you haven't discriminated anything

ssalbdivad•2d ago

In the other case, it falls back to a better discriminant at the root of the type

ahrjarrettOP•2d ago

oh okay, that makes more sense. cool i've got a workaround here locally, but i'll follow that issue so i know when i can rip it out

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Can the output of `.json` be used to construct an arktype schema?

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