How to set a custom message with object type?

Hi guys, I'm new to Arktype, I'm switching from Zod to Arktype with this code:

export const TestSchema = z.object({
  companyName: z
    .string()
    .min(2, "Company name must be at least 2 characters")
    .max(50, "Company name must be less than 50 characters"),
  companyId: z
    .string()
    .min(2, "Company ID must be at least 2 characters")
    .max(50, "Company ID must be less than 50 characters"),
  agreement: z.boolean(),
});

export const TestSchema = z.object({
  companyName: z
    .string()
    .min(2, "Company name must be at least 2 characters")
    .max(50, "Company name must be less than 50 characters"),
  companyId: z
    .string()
    .min(2, "Company ID must be at least 2 characters")
    .max(50, "Company ID must be less than 50 characters"),
  agreement: z.boolean(),
});

So far, I switched to this in Arktype:

export const TestSchema = type({
  companyName: "2 <= string <= 50",
  companyId: "2 <= string <= 50",
  agreement: "boolean",
});

export const TestSchema = type({
  companyName: "2 <= string <= 50",
  companyId: "2 <= string <= 50",
  agreement: "boolean",
});

However, I'm not sure how to set a custom message. All of the documents refer to only one variable. https://arktype.io/docs/configuration#errors. Is there any way to set the error message for best practices? ❤️

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27 Replies

TizzySaurus•3w ago

What exactly do you need that the linked docs don't provide? I guess you want custom error messages per key. I think you can do that by just wrapping the values in another type() call. So something like

const t = type({
    companyName: type("2 <= string <= 50").describe("a company name"),
    ...
});

const t = type({
    companyName: type("2 <= string <= 50").describe("a company name"),
    ...
});

teddythinhOP•3w ago

Thanks for your explanation. I have managed to make it work now. Also, can the value message be separated with constraints? For example, if the value = 2, I would have a different message, and if the value >= 50, it would be another message.

TizzySaurus•3w ago

You can look at the .configure examples ctx.value has the value iirc Err actually it might be a separate parameter. I.e. (ctx, value) => .... I honestly can't remember

teddythinhOP•3w ago

Hmmm I have tried to use ctx.actual but it cannot be used with operations like > or <

TizzySaurus•3w ago

Well, I guess because it's a string? So you need to use >/< on ctx.actual.length ctx.actual seems vaguely familiar as the correct thing here

teddythinhOP•3w ago

I have tried this one, it's only check the first condition, not sure if it's best practice:

  companyName: type("2 <= string <= 50").configure({
    message: (ctx) => {
      return ctx.actual.length < 2
        ? "Company name must be at least 2 characters long"
        : ctx.actual.length > 50
          ? "Company name must be at most 50 characters long"
          : "";
    },
  }),
  companyId: type("2 <= string <= 50").configure({
    message: (ctx) => {
      return ctx.actual.length < 2
        ? "Company ID must be at least 2 characters long"
        : ctx.actual.length > 50
          ? "Company ID must be at most 50 characters long"
          : "";
    },
  }),

  companyName: type("2 <= string <= 50").configure({
    message: (ctx) => {
      return ctx.actual.length < 2
        ? "Company name must be at least 2 characters long"
        : ctx.actual.length > 50
          ? "Company name must be at most 50 characters long"
          : "";
    },
  }),
  companyId: type("2 <= string <= 50").configure({
    message: (ctx) => {
      return ctx.actual.length < 2
        ? "Company ID must be at least 2 characters long"
        : ctx.actual.length > 50
          ? "Company ID must be at most 50 characters long"
          : "";
    },
  }),

TizzySaurus•3w ago

Out of interest, what's the default error message without any of this config? I think it should be pretty much the same ArkType has very good default error messages And using expected is better than using message because that's the API used internally (then your full error message will be something like {key} must be {expected} (was {actual}) iirc) It's only if you really don't want that error message format you should use message (but keep in mind the other errors will still use that format) Also I guess you might have to handle when the ctx.actual isn't a string? Since that would also give an error. Not entirely sure though. I guess if ctx.actual is typed as a string then it's probably fine without I'm thinking the : "" shouldn't be necessary because in theory this will only be called when there's an error. So you can do if isTooShort ? tooShortMessage: tooLongMessage (you don't need the extra if statement for checking if it's too long, since that's the only remaining possibility) (If it wasn't clear, I'm just guessing this stuff, because I honestly just can't remember)

teddythinhOP•3w ago

Okay, I understand now, currently the error looks like this. I just want to change the "companyId must be..." to "Company ID must be...". Arktype is taking the variable name that I define and showing it on the UI.

TizzySaurus•3w ago

Ah right yeah, I see I wonder if there's maybe a way to change just the "companyId" bit, but I'm not aware of one What did you end up going with?

teddythinhOP•3w ago

I haven't tried anything yet 😂 I don't know what the solution can be used here haha Hi @TizzySaurus , so is there any solution for this one?

TizzySaurus•3w ago

The narrow thing should work If you want it to check all keys then I think you'd need a top level narrow that returns an array of the ctx.mustBe I'll write something up when I'm at my PC and can test things (will probably be ~10+ hours since I have a busy day)

teddythinhOP•3w ago

Sure, take your time, no need to rush. I appreciate @TizzySaurus ❤️

ssalbdivad•3w ago

Try this:

const companyId = type("2 <= string <= 50").configure({
    problem: ctx => `Company ID must be ${ctx.expected} (was ${ctx.actual})`
})

const companyId = type("2 <= string <= 50").configure({
    problem: ctx => `Company ID must be ${ctx.expected} (was ${ctx.actual})`
})

TizzySaurus•3w ago

const t = type({
    companyId: [
        "2 <= string <= 50",
        "@",
        { problem: ctx => `Company ID must be ${ctx.expected} (was ${ctx.actual})` }
    ],
    companyName: [
        "2 <= string <= 50",
        "@",
        {
            problem: ctx => `Company name must be ${ctx.expected} (was ${ctx.actual})`
        }
    ]
})

console.log(t.assert({ companyId: "t", companyName: "o" }))

const t = type({
    companyId: [
        "2 <= string <= 50",
        "@",
        { problem: ctx => `Company ID must be ${ctx.expected} (was ${ctx.actual})` }
    ],
    companyName: [
        "2 <= string <= 50",
        "@",
        {
            problem: ctx => `Company name must be ${ctx.expected} (was ${ctx.actual})`
        }
    ]
})

console.log(t.assert({ companyId: "t", companyName: "o" }))

thoughts?

TizzySaurus•3w ago

I guess you want it without the key name

TizzySaurus•3w ago

Which, for the record, is what changing problem to message does:

TizzySaurus•3w ago

The [x, "@", y] is just the inline version of type(x).configure(y) btw, if that wasn't clear

TizzySaurus•3w ago

And if you want to see the errors separately so that you can show them on their respective input boxes, here's how you can do that:

const result = t({ companyId: "t", companyName: "valid" })
if (result instanceof type.errors) {
    console.log("foo: ", result.byPath["companyId"]?.message) // our custom error message
    console.log("bar: ", result.byPath["companyName"]?.message) // undefined since there's no error at this key
}

const result = t({ companyId: "t", companyName: "valid" })
if (result instanceof type.errors) {
    console.log("foo: ", result.byPath["companyId"]?.message) // our custom error message
    console.log("bar: ", result.byPath["companyName"]?.message) // undefined since there's no error at this key
}

TizzySaurus•3w ago

Hopefully that helps @teddythinh :)

teddythinhOP•3w ago

Thanks guys. Let me try it and get back to you. ❤️

TizzySaurus•3w ago

Were you able to try it out?

teddythinhOP•3w ago

Hi @ssalbdivad, I tried your solution here:

export const TestSchema = type({
  companyName: type("2 <= string <= 50").configure({
    problem: (ctx) => `Company name must be ${ctx.expected} (was ${ctx.actual})`,
  }),
  companyId: type("2 <= string <= 50").configure({
    problem: (ctx) => `Company ID must be ${ctx.expected} (was ${ctx.actual})`,
  }),
});

export const TestSchema = type({
  companyName: type("2 <= string <= 50").configure({
    problem: (ctx) => `Company name must be ${ctx.expected} (was ${ctx.actual})`,
  }),
  companyId: type("2 <= string <= 50").configure({
    problem: (ctx) => `Company ID must be ${ctx.expected} (was ${ctx.actual})`,
  }),
});

but it's still end up with the same thing.

teddythinhOP•3w ago

Hi @TizzySaurus, I manage to remove the key name by changing problem to message with @ssalbdivad's solution here:

export const TestSchema = type({
  companyName: type("2 <= string <= 50").configure({
    message: (ctx) => `Company name must be ${ctx.expected} (was ${ctx.actual})`,
  }),
  companyId: type("2 <= string <= 50").configure({
    message: (ctx) => `Company ID must be ${ctx.expected} (was ${ctx.actual})`,
  }),
});

export const TestSchema = type({
  companyName: type("2 <= string <= 50").configure({
    message: (ctx) => `Company name must be ${ctx.expected} (was ${ctx.actual})`,
  }),
  companyId: type("2 <= string <= 50").configure({
    message: (ctx) => `Company ID must be ${ctx.expected} (was ${ctx.actual})`,
  }),
});

teddythinhOP•3w ago

Thank you guys @TizzySaurus @ssalbdivad for helping me ❤️

ssalbdivad•3w ago

Good call, my bad there!

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