feat: export type 'Format'

[matthiashermsen]

When adding a custom format via

const customFormat = { ... };
ajvInstance.addFormat('customFormat', customFormat);

the variable customFormat must be of type Format. It would be nice to import this type from validate-value, otherwise one must install ajv in addition.

[goloroden]

Hey @matthiashermsen 👋

Thanks for bringing up this PR 😊

I'm not sure if I got this correctly: If you want to register a custom format, AFAICS you need a custom ajv instance, so you must install and import ajv by yourself anyway. Am I missing something?

[matthiashermsen]

@goloroden Hey :)

It is possible to get a custom ajv instance from validate-value ( getDefaultAjvInstance() )

Given the following sample code

import { getDefaultAjvInstance, Parser } from 'validate-value';

const createParser = function (): Parser<T> {
  const ajvInstance = getDefaultAjvInstance();

  const myCustomFormat = {
    type: 'string',
    validate: (candidate: string) => !!candidate
  };

  ajvInstance.addFormat('myCustomFormat', myCustomFormat);

  return new Parser<T>(schema(), { ajvInstance });
};

This won't work, because TS can't infer myCustomFormat to Format which is required for the addFormat function. You will get the error

Argument of type '{ type: string; validate: (candidate: string) => boolean; }' is not assignable to parameter of type 'Format'.
Property 'async' is missing in type '{ type: string; validate: (candidate: string) => boolean; }' but required in type 'AsyncFormatDefinition'.ts(2345)

It is possible to change the code to

import { getDefaultAjvInstance, Parser } from 'validate-value';

const createParser = function (): Parser<T> {
  const ajvInstance = getDefaultAjvInstance();

  ajvInstance.addFormat('myCustomFormat', {
    type: 'string',
    validate: (candidate: string) => !!candidate
  });

  return new Parser<T>(schema(), { ajvInstance });
};

but in my case, it should import the Format from another file and unfortunately I can't import this type from validate-value.

import { Format } from 'validate-value'; // Module '"validate-value"' has no exported member 'Format'

const myCustomFormat = { // It doesn't know that this should be of type `Format`
  type: 'string',
  validate: (candidate: string) => !!candidate
};

For now I solved this by installing ajv but I think it is better to depend only on validate-value ( the packages might be out of sync
or validate-value might use different technologies in the future )

[goloroden]

Makes sense 👍