Async/Await with Archetype

archetype-20171117-async-await.js

const Archetype = require('archetype');

const UserType = new Archetype({
  name: { $type: 'string' },
  age: { $type: 'number' }
}).compile('UserType');

// Prints 'age: Could not cast "not a number" to number'
throwError().catch(error => console.error(error.message));

catchError().catch(() => { console.log('unexpected error'); });

async function throwError() {
  // `new UserType()` throws an error if casting fails. In this case,
  // archetype will fail to coerce `age` into a number. This exception
  // will bubble up to the promise this async function returns.
  new UserType({ name: 'test', age: 'not a number' });
  // This means you don't need to do an `if (error != null) {}` check
  // here. Leave that masochism in Golang where it belongs.
}

async function catchError() {
  try {
    new UserType({ name: { hello: 'world' } });
  } catch (error) {
    // Prints 'Caught name: Could not cast "[object Object]" to string'
    console.log('Caught', error.message);
  }
  // Execution continues normally, no error. Archetype throws errors
  // by default in order to better integrate with async/await, because
  // usually malformed input should cause your business logic should fail
  // fast. But if you don't want to bubble up the error, try/catch is
  // the way to go.
}