How can I validate a `Set` of certain item type?

Hello, I am trying to create a schema that validates that a property is a set of strings:

const schema = type({
  items: "Set<string>"
});

const schema = type({
  items: "Set<string>"
});

But that gives me an error. I checked the docs, and nothing seems to cover Maps or Sets. Am I missing something, or aren't they supported? Thanks.

2 Replies

ssalbdivad•4d ago

For now you would have to use something like this:

const stringSet = type("Set").narrow((set, ctx): set is Set<String> => {
    const nonStrings = [...set.values()].filter(v => typeof v !== "string")
    if (nonStrings.length)
        return ctx.reject({
            expected: "a Set<string>",
            actual: `invalid due to the values: ${nonStrings}`
        })
    return true
})

const stringSet = type("Set").narrow((set, ctx): set is Set<String> => {
    const nonStrings = [...set.values()].filter(v => typeof v !== "string")
    if (nonStrings.length)
        return ctx.reject({
            expected: "a Set<string>",
            actual: `invalid due to the values: ${nonStrings}`
        })
    return true
})

We will be able to support Set<string> once default values for generics are supported: https://github.com/arktypeio/arktype/issues/1054

GitHub

Default values for generic parameters · Issue #1054 · arktypeio/a...

Would allow parsing the equivalent syntax from TS: const array = type("<t = unknown>", "t[]"); // unknown[] const a = array(); // string[] const b = array("string&quo...

winterboltOP•3d ago

Thanks!

Gaming

Programming

How can I validate a `Set` of certain item type?

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