Quickstart

Three minutes from a fresh terminal to a validating PDTF transaction in JavaScript.

1. Install

npm install @pdtf/schemas

The package bundles the base transaction schema, all 18 main overlays, and the 16 NTS2 extension overlays. ~1 MB installed.

2. Get a merged schema

Pick the overlays your use case needs (here: BASPI v5 for an estate-agent product):

const { getTransactionSchema } = require('@pdtf/schemas');

const schema = getTransactionSchema(
  'https://trust.propdata.org.uk/schemas/v3/pdtf-transaction.json',
  ['baspi5']
);

Under the hood, getTransactionSchema deep-merges the base transaction schema with each named overlay. See Schema composition for the merge rules.

3. Validate

const { getValidator } = require('@pdtf/schemas');

const validate = getValidator(
  'https://trust.propdata.org.uk/schemas/v3/pdtf-transaction.json',
  ['baspi5']
);

const transaction = require('./my-transaction.json');
if (validate(transaction)) {
  console.log('Valid');
} else {
  console.error(validate.errors);
}

getValidator returns an Ajv-compiled validator function with all the right keywords (format, discriminator, etc.) configured. validate.errors follows the standard Ajv error format.

4. Multiple overlays

Compose several overlays — they merge cumulatively:

// A conveyancer reviewing a leasehold sale
const schema = getTransactionSchema(baseId, [
  'baspi5', 'ta6', 'ta7', 'ta10', 'lpe1'
]);

5. Extension overlays

The NTS2 extension overlays let you compose specific sub-features piecemeal — for a staged NTS → NTS2 migration, you can add just Japanese knotweed and transfer fees:

const schema = getTransactionSchema(baseId, ['nts2023', 'jk', 'tf']);

The full list of overlay aliases is in the PDTF overlays page.

6. Example transactions

Sample transactions are at source/03-standards/schemas/src/examples/v3/. Worth running through your validator as a first sanity check.

Where next

• Schema composition — for the deep-merge mechanics and gotchas (custom arrayMerge, required handling, oneOf conditionals)
• Validation — for Ajv configuration, error decoding, validating verified claims
• Verified claims — for signing transaction fragments as W3C VCs
• The repo's schemas/README.md and CLAUDE.md for developer-friendly walkthroughs