Zod: Establishing minimum and maximum values after converting a string to a numerical value

Question

Zod: Establishing minimum and maximum values after converting a string to a numerical value

When dealing with a number or numeric string, I aim to convert it to a number and then validate it using the .min() and .max() methods. However, the results are not matching my expectations.

const numberValid = z.number().or(z.string().regex(/^\d+$/).transform(Number));

const positiveNumber = numberValid.min(0); // Unfortunately, the method does not seem to exist

typescript zod

Answer 1

Answer №1

Starting from version 3.20, you have the ability to utilize z.coerce.number() in this manner:

const validatedNumber = z.coerce.number().min(0)

validatedNumber.parse(123) // Valid
validatedNumber.parse(-123) // Invalid
validatedNumber.parse("123") // Valid
validatedNumber.parse("-123") // Invalid

Answer 2

Starting from version 3.20, you have the ability to utilize z.coerce.number() in this manner:

const validatedNumber = z.coerce.number().min(0)

validatedNumber.parse(123) // Valid
validatedNumber.parse(-123) // Invalid
validatedNumber.parse("123") // Valid
validatedNumber.parse("-123") // Invalid

Answer 3

Answer №2

The issue here is that the transform method is returning a z.ZodEffect, which provides further transformation methods, but loses the original type information of z.string. As a result, the min method from z.number is not accessible because the outer type is z.ZodUnion, which does not recognize the min refinement.

To achieve the desired behavior, you could consider the following approach:

const thing = z
  .number()
  .or(z.string().regex(/\d+/).transform(Number))
  .refine((n) => n >= 0);

Although this solution may seem somewhat lacking, as it does not allow for using min with its simplified syntax and clearer error messages, you could address this by providing a custom message like

{ message: 'value was less than 0' }

as the second argument to the refine method.

Edit

Upon further consideration, another approach is possible. You can utilize the preprocess function to preprocess strings before passing them to z.number. By implementing it this way, you can still make use of .min with its detailed error messages and other functionalities.

const numberValid2 = z.preprocess(
  (input) => {
    const processed = z.string().regex(/^\d+$/).transform(Number).safeParse(input);
    return processed.success ? processed.data : input;
  },
  z.number().min(0),
)

Answer 4

The issue here is that the transform method is returning a z.ZodEffect, which provides further transformation methods, but loses the original type information of z.string. As a result, the min method from z.number is not accessible because the outer type is z.ZodUnion, which does not recognize the min refinement.

To achieve the desired behavior, you could consider the following approach:

const thing = z
  .number()
  .or(z.string().regex(/\d+/).transform(Number))
  .refine((n) => n >= 0);

Although this solution may seem somewhat lacking, as it does not allow for using min with its simplified syntax and clearer error messages, you could address this by providing a custom message like

{ message: 'value was less than 0' }

as the second argument to the refine method.

Edit

Upon further consideration, another approach is possible. You can utilize the preprocess function to preprocess strings before passing them to z.number. By implementing it this way, you can still make use of .min with its detailed error messages and other functionalities.

const numberValid2 = z.preprocess(
  (input) => {
    const processed = z.string().regex(/^\d+$/).transform(Number).safeParse(input);
    return processed.success ? processed.data : input;
  },
  z.number().min(0),
)

Answer 5

Answer №3

 z.word() 
.modify((year) => parseInt(year)) 
.pipe(z.integer().minimum(1900)) 
.modify((year) => year.toString())

Answer 6

 z.word() 
.modify((year) => parseInt(year)) 
.pipe(z.integer().minimum(1900)) 
.modify((year) => year.toString())

Zod: Establishing minimum and maximum values after converting a string to a numerical value

Answer №1

Answer №2

Edit

Answer №3

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