Server-Side Development with Hapi.js — Throw 400-Series Errors

Hapi.js is a small Node framework for developing back end web apps.

In this article, we’ll look at how to create back end apps with Hapi.js.

Method Not Allowed Error

We can throw a method not allowed error with @hapi/boom ‘s methodNotAllowed method.

For instance, we can write:

const Hapi = require('@hapi/hapi');
const Boom = require('@hapi/boom');

const init = async () => {
  const server = new Hapi.Server({
    port: 3000,
    host: '0.0.0.0'
  });

  server.route({
    method: 'GET',
    path: '/',
    handler(request, h) {
      throw Boom.methodNotAllowed('that method is not allowed');
    }
  });

  await server.start();
  console.log('Server running at:', server.info.uri);
};
process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});
init();

Then we get:

{"statusCode":405,"error":"Method Not Allowed","message":"that method is not allowed"}

as the response.

We can set the Allow header with the 3rd argument.

To do this, we write:

const Hapi = require('@hapi/hapi');
const Boom = require('@hapi/boom');

const init = async () => {
  const server = new Hapi.Server({
    port: 3000,
    host: '0.0.0.0'
  });

  server.route({
    method: 'GET',
    path: '/',
    handler(request, h) {
      throw Boom.methodNotAllowed('that method is not allowed', 'data', ['foo', 'bar']);
    }
  });

  await server.start();
  console.log('Server running at:', server.info.uri);
};
process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});
init();

Now we should see that Allow response header has foo, bar as its value.

Not Acceptable Error

We can call the Boom.notAcceptable method to return a 406 error.

For instance, we can write:

const Hapi = require('@hapi/hapi');
const Boom = require('@hapi/boom');

const init = async () => {
  const server = new Hapi.Server({
    port: 3000,
    host: '0.0.0.0'
  });

  server.route({
    method: 'GET',
    path: '/',
    handler(request, h) {
      throw Boom.notAcceptable('unacceptable');
    }
  });

  await server.start();
  console.log('Server running at:', server.info.uri);
};
process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});
init();

Then we get:

{
    "statusCode": 406,
    "error": "Not Acceptable",
    "message": "unacceptable"
}

as the response.

We can also pass in extra data into the 2nd argument.

Proxy Required Error

We call the Boom.proxyAuthRequired method to return a 407 response.

For instance, we can write:

const Hapi = require('@hapi/hapi');
const Boom = require('@hapi/boom');

const init = async () => {
  const server = new Hapi.Server({
    port: 3000,
    host: '0.0.0.0'
  });

  server.route({
    method: 'GET',
    path: '/',
    handler(request, h) {
      throw Boom.proxyAuthRequired('auth missing');
    }
  });

  await server.start();
  console.log('Server running at:', server.info.uri);
};
process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});
init();

Then we get:

{
    "statusCode": 407,
    "error": "Proxy Authentication Required",
    "message": "auth missing"
}

as the response.

We can also pass in more data as the 2nd argument.

Request Timeout

We can throw a request timeout error with the Boom.clientTimeout method:

const Hapi = require('@hapi/hapi');
const Boom = require('@hapi/boom');

const init = async () => {
  const server = new Hapi.Server({
    port: 3000,
    host: '0.0.0.0'
  });

  server.route({
    method: 'GET',
    path: '/',
    handler(request, h) {
      throw Boom.clientTimeout('timed out');
    }
  });

  await server.start();
  console.log('Server running at:', server.info.uri);
};
process.on('unhandledRejection', (err) => {
  console.log(err);
  process.exit(1);
});
init();

Then we get:

{"statusCode":408,"error":"Request Time-out","message":"timed out"}

as the response.

We can also pass in more data as the 2nd argument.

Conclusion

We can throw many types of errors easily with the @hapi/boom module.