# Custom API Hooks

Custom API Hooks allow running custom logic when a specified event occurs within your project. Types of API hooks are Actions, Filters, Init, and Schedule.

# Types of Hooks

Use filter hooks when you want the hook to fire before the event. Use action hooks when you want the hook to fire after the event.

Hooks can impact performance when not carefully implemented. Filter hooks happen before the event fires, making them much more susceptible to performance issues. Hooks on read actions can also impact performance since a single request can result in many database reads.

# Action

An action event executes after a defined event and receives data related to the event. Use actions hooks when you need to automate responses to CRUD events on items or server actions.

The action register function receives two parameters:

  • The event name
  • A callback function that is executed whenever the event fires.

The callback function itself receives two parameters:

  • An event-specific meta object
  • A context object

The context object has the following properties:

  • database — The current database transaction
  • schema — The current API schema in use
  • accountability — Information about the current user

An example of restricting CRUD events to administrator accounts:

module.exports = function registerHook({ action, { exceptions } }) {
	const { ForbiddenException } = exceptions;

	const adminOnly = async (_, { accountability }) => {
		if (accountability.admin !== true) throw new ForbiddenException();
	};

	action('items.create', adminOnly);
	action('items.read', adminOnly);
	action('items.update', adminOnly);
	action('items.delete', adminOnly);
};

# Filter

Filter hooks act on the event's payload before the event is fired. They allow you to check, modify, or cancel an event.

Below is an example of canceling a create event by throwing a standard Directus exception.

module.exports = function registerHook({ filter }, { exceptions }) {
	const { InvalidPayloadException } = exceptions;

	filter('items.create', async (input) => {
		if (LOGIC_TO_CANCEL_EVENT) {
			throw new InvalidPayloadException(WHAT_IS_WRONG);
		}

		return input;
	});
};

The filter register function receives two parameters:

  • The event name
  • A callback function that is executed whenever the event fires.

The callback function itself receives three parameters:

  • The modifiable payload
  • An event-specific meta object
  • A context object

The context object has the following properties:

  • database — The current database transaction
  • schema — The current API schema in use
  • accountability — Information about the current user

# Init

An init event executes at a defined point within the lifecycle of Directus. Use init event objects to inject logic into internal services.

The init register function receives two parameters:

  • The event name
  • A callback function that is executed whenever the event fires.

The callback function itself receives one parameter:

  • An event-specific meta object

# Schedule

A schedule event executes at certain points in time rather than when Directus performs a specific action. This is supported through node-cron (opens new window). To set up a scheduled event, provide a cron statement as the first parameter to the schedule() function. For example schedule('15 14 1 * *', <...>) (at 14:15 on day-of-month 1) or schedule('5 4 * * sun', <...>) (at 04:05 on Sunday). See example below:

const axios = require('axios');

module.exports = function registerHook({ schedule }) {
	schedule('*/15 * * * *', async () => {
		await axios.post('http://example.com/webhook', { message: 'Another 15 minutes passed...' });
	});
};

# Available Events

# Action Events

Name Meta
server.start server
server.stop server
response request, response, ip, duration, finished
auth.login payload, status, user, provider
files.upload payload, key, collection
(<collection>.)items.read payload, query, collection
(<collection>.)items.create payload, key, collection
(<collection>.)items.update payload, keys, collection
(<collection>.)items.delete payload, collection
<system-collection>.create payload, key, collection
<system-collection>.update payload, keys, collection
<system-collection>.delete payload, collection

System Collections

<system-collection> should be replaced with one of the system collection names activity, collections, fields, folders, permissions, presets, relations, revisions, roles, settings, users or webhooks.

# Filter Events

Name Payload Meta
request.not_found false request, response
request.error The request errors --
database.error The database error client
auth.login The login payload status, user, provider
auth.jwt The auth token status, user, provider, type
(<collection>.)items.create The new item collection
(<collection>.)items.update The updated item keys, collection
(<collection>.)items.delete The keys of the item collection
<system-collection>.create The new item collection
<system-collection>.update The updated item keys, collection
<system-collection>.delete The keys of the item collection

System Collections

<system-collection> should be replaced with one of the system collection names activity, collections, fields, folders, permissions, presets, relations, revisions, roles, settings, users or webhooks.

# Init Events

Name Meta
cli.before program
cli.after program
app.before app
app.after app
routes.before app
routes.after app
routes.custom.before app
routes.custom.after app
middlewares.before app
middlewares.after app

# Creating a Hook

# 1. Create a Hook File

Custom hooks are dynamically loaded from within your extensions folder. By default, this directory is located at /extensions, but it can be configured within your project's env file to be located anywhere. The hook-id is the name of your hook.

# Default Standalone Hook Location

/extensions/hooks/<hook-id>/index.js

# 2. Register your Hook

The registerHook function receives an object containing the type-specific register functions as the first parameter:

  • filter — Listen for a filter event
  • action — Listen for an action event
  • init — Listen for an init event
  • schedule — Execute a function at certain points in time

A second parameter is a context object with the following properties:

  • services — All API internal services
  • exceptions — API exception objects that can be used for throwing "proper" errors
  • database — Knex instance that is connected to the current database
  • getSchema — Async function that reads the full available schema for use in services
  • env — Parsed environment variables
  • loggerPino (opens new window) instance.

Each custom hook is registered to its event scope using a function with the following format:

const axios = require('axios');

module.exports = function registerHook({ action }) {
	action('items.create', () => {
		axios.post('http://example.com/webhook');
	});
};

# 3. Develop your Custom Hook

Trigger your custom hook with any of the platform's many API events.

Event names consist of multiple scopes delimited by a dot:

<scope>.<scope>...
// eg: items.create
// eg: users.update
// eg: auth.login
// eg: routes.custom.before

Using the example from step 2, action() is the hook type and it receives two arguments. items.create is the API event that should trigger the hook. It also receives a callback function that says what the hook should do when the API event occurs.

const axios = require('axios');

module.exports = function registerHook({ action }) {
	action('items.create', () => {
		axios.post('http://example.com/webhook');
	});
};

# 4. Restart the API

To deploy your hook, restart the API by running:

npx directus start

# Full Example

extensions/hooks/sync-with-external/index.js:

const axios = require('axios');

module.exports = function registerHook({ filter, action }, { services, exceptions }) {
	const { MailService } = services;
	const { ServiceUnavailableException, ForbiddenException } = exceptions;

	// Sync with external recipes service, cancel creation on failure
	filter('items.create', async (input, { collection }, { schema }) => {
		if (collection !== 'recipes') return input;

		const mailService = new MailService({ schema });

		try {
			await axios.post('https://example.com/recipes', input);
			await mailService.send({
				to: 'person@example.com',
				template: {
					name: 'item-created',
					data: {
						collection: collection,
					},
				},
			});
		} catch (error) {
			throw new ServiceUnavailableException(error);
		}

		input.syncedWithExample = true;

		return input;
	});

	// Force everything to be admin-only at all times
	const adminOnly = async (_, { accountability }) => {
		if (accountability.admin !== true) throw new ForbiddenException();
	};

	action('items.create', adminOnly);
	action('items.read', adminOnly);
	action('items.update', adminOnly);
	action('items.delete', adminOnly);
};
Last Updated: 11/24/2021, 10:12:29 PM