Custom Matchers

Since @withease/contracts is built on top of Contract, you can embed your own matcher into the schema naturally.

Let us write a custom matcher that checks if an age of a user is within a certain range:

import { type Contract, and, num } from '@withease/contracts';

function age({ min, max }: { min: number; max: number }) {
  return and(num, {
    isData: (data) => data >= min && data <= max,
    getErrorMessages: (data) => [
      `Expected a number between ${min} and ${max}, but got ${data}`,
    ],
  });
}

Now you can use this matcher in your schema:

import { obj, str } from '@withease/contracts';

const User = obj({
  name: str,
  age: age(18, 100),
});