Serializers

Serializers convert processed values back to a format suitable for output. This is optional and primarily used when you want to output values in a readable format, or if normalization produces a value that cannot be serialized.

For example, here is a timestamp schema that normalizes to milliseconds, but serializes to ISO strings:

import { Schema, SchemaResolver } from '@versionzero/schema';
const resolver = new SchemaResolver();

const timestampNormalizer = (value) => {
  if (typeof value === 'number') {
    if (value < 0) {
      throw new Error(`Invalid negative timestamp value: ${value}`);
    }
    return value;
  }
  else if (!value || value === 'now') {
    return Date.now();
  }
  else if (typeof value === 'string') {
    let t = new Date(value).getTime()
    if (isNaN(t)) {
      throw new Error(`Invalid timestamp value: ${value}`);
    }
    return t;
  }
  throw new Error(`Invalid timestamp value: ${value}`);
};

const timestampSerializer = (value) => {
  return new Date(value).toISOString();
};

const schema = await resolver.compile(
  new Schema('object')
    .property('createdAt', new Schema()
      .normalizer(timestampNormalizer)
      .validator(['$is-number', '$positive'])      
      .serializer(timestampSerializer)
    )
);

const ts = await schema.process({createdAt: 'now'});

console.log(ts);                            // -> { createdAt: <number> }
console.log(await schema.serialize(ts));    // -> { createdAt: '<iso date>' }