How to get a list of validated elements

Author: mrblond1nCreated Aug 31, 2022Updated Aug 12, 2024

I have a function that takes codec and data as arguments.

like this

typescript

import * as t from 'io-ts';

export const decode = <C extends t.Any>(codec: C, data: unknown): t.TypeOf<C> => {
    const either = codec.decode(data);

    if (either._tag === 'Right') {
        return either.right;
    } else {
        throw new Error('no matches');
    }
};

And this function work correctly. For example: I get array of some objects and check via some codec

codec like this

typescript

import * as t from 'io-ts';

const ItemDto = t.type({
    value: t.string,
    id: t.string,
});

export const ItemsCodec = t.array(ItemDto)

And if some field to be wrong for example, value is Number type - decode fn throw Error.

However, I want the function to return valid elements from the list.

For example:

typescript

const data = [
  {
    value: 'valid item',
    id: '1'
  },
  {
    value: 'not valid item',
    id: '2'
  }
]


const result = decode(ItemsCodec, data) 

/*
 * result is [
 *   {
 *       value: 'valid item',
 *       id: '1'
 *   }
 * ]
 * */

It is possible?

Source: gcanti/io-ts

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