Handle Webhooks with GraphQL Subscriptions

GraphQL Mesh can consume Webhooks as GraphQL Subscriptions in the unified schema by using built-in PubSub implementation

Add new Subscription field#

You can use additionalTypeDefs and additionalResolvers to add subscription root fields to your unified schema.

additionalTypeDefs: |
  # If you don't have Subscription type defined anywhere
  # You have to extend subscription definition
  extend schema {
    subscription: Subscription
  }
  type Subscription {
    todoAdded: Todo
  }
additionalResolvers:
  - type: Subscription
    field: todoAdded
    pubsubTopic: todoAdded

We're able to use existing types from our unified schema, and this root field is subscribed to our specific topic in our PubSub service.

Use JSON Schema Handler instead#

You can also use JSON Schema handler if you don't want to write an extra GraphQL type definitions. You can generate GraphQL type definitions from sample JSON response;

Just add the following to your existing JSON schema handler configuration in .meshrc.yml file;

          - type: Subscription
            field: todoAdded
            pubsubTopic: todoAdded
            responseSample: ./todo.json

Handle Webhook HTTP Requests#

Add custom express handler to listen specific path for your HTTP Webhook on Mesh CLI Server. You can do it either in a programmatic or declarative way.

Using Declarative API#

Let's say you have running GraphQL Mesh server listening 4000 port, and you need to listen a specific route for upcoming HTTP requests as HTTP Webhook.

serve:
  port: 4000
  handlers:
    - path: /webhooks/todo_added
      pubsubTopic: todoAdded

path defines the path in our server that will receive HTTP requests as "Webhook" from our API then send it to pubsubTopic.

Custom Handler in Code#

handler can get any kind of Express request handler. So you can extend Mesh Server however you want.

serve:
  port: 4000
  handlers:
    - path: /webhooks/todo_added
      handler: ./todo_added.handler.js

and in todo_added_handler.js we have something like following;

module.exports = (req, res) => {
    // Mesh PubSub instance is available under `req`
    req.pubsub.publish('todoAdded', req.body);
    res.end(); // Don't forget to finish the HTTP connection
};

You can check out our example