arktype•2w ago

ToJsonSchema fails with narrow

Hi short question, i might be missing something obvious. If I try to convert a type to jsonschema with a narrow function it fails every time, even if I use the .in property.

const url = type("string")
        .narrow((s, ctx) => {
            if (isValidHttpUrl(s)) {
                return true;
            }

            return ctx.mustBe("a valid URL");
        });

// FAILS:
url.in.toJsonSchema()

// EXPECTED:
{ type: 'string' }

const url = type("string")
        .narrow((s, ctx) => {
            if (isValidHttpUrl(s)) {
                return true;
            }

            return ctx.mustBe("a valid URL");
        });

// FAILS:
url.in.toJsonSchema()

// EXPECTED:
{ type: 'string' }

21 Replies

ssalbdivad•2w ago

What does the error message say?

Möhre•2w ago

Uncaught ParseError: Predicate $ark.fn19 is not convertible to JSON Schema

ssalbdivad•2w ago

Well it makes sense right? It's saying you have a condition on your type that can't be represented in JSON schema so it fails

Möhre•2w ago

I guess but i thought the in property takes the input types which would be string

ssalbdivad•2w ago

Maybe at some point there will be a "loose" toJsonSchema where if there are custom predicates (you narrow your type) it will strip them out, but that doesn't exist yet. Anything you can use a regex for can be converted directly It takes the input type of your transformation, but narrowing is not a transformation it's just an assertion

Möhre•2w ago

I know atleast for the url there is a type, was just an example. Would pipe work for that?

ssalbdivad•2w ago

Yeah if you pipe it to itself but do the extra check there, then you can extract .in, it would work

Möhre•2w ago

I see, thanks for the clarification. A kinda loose or lax mode for that would be very helpful!

ssalbdivad•2w ago

Feel free to create an issue! Would definitely be interested in adding that at some point or accepting contributions

Möhre•2w ago

Allright!

Randall•6d ago

So narrow can make a type break jsonschema. Morph OK? Sometimes names help clarity. Restrict, narrow, transform, morph, validate,... thesaurus. X like y& lax semantic Any AT constructs that can feed jsonschema native constraints? OK to rtfm me, night here rn

ssalbdivad•6d ago

I don't know if this was intentionally ironic but this is so hard to understand 😅

Randall•6d ago

Phone kb sry

ssalbdivad•6d ago

You don't just have to rely on naming just think "can this thing be represented in JSON schema"? If it's a custom function or symbol or something it can't, there are clear errors

Randall•3d ago

'Course Will rety later What I was trying to say was that a) I understand using narrow() screws up the chance to represent a type as JSON-Schema. b) I'm assuming morph works fine, not affecting the JSON-Schema output. c) I wonder if some variant fitting between those two somehow could express a type that produces a valid JSON-Schema, while still capturing the functionality restricting actual data in ways that would raise (post-schema) validation failures. Just as morph could explode if it sees something it doesn't like, and recognizing that not every possible constraint/restriction/transform/validate may be expressible within JSON-Schema's capabilities, yet still be fundamentally part of the data's domain model. d) those ...names could be ideas for how to name an API call expressing such facts about the domain model. and finally e) I'm assuming that basic min/max constraints "< 4" would be representable in JSON-Schema (are they?) ... and others?

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ToJsonSchema fails with narrow