Subscription server notifications using GraphQL

First define a Deal type in schema. graphQL:

We simulate a scenario where we expect to receive notification from the server side whenever a new transaction occurs.

Create a new subscription with a field of deal and type of the deal just defined:

This subscription implementation simply prints a notification every 2 seconds:

const deal = {
      subscribe: (parent, args, { pubsub }) => {
        const channel = Math.random().toString(36).substring(2, 15) // random channel name
        setInterval(
          () => pubsub.publish(channel, { deal: {description: "New deal!"}}),2000);
        return pubsub.asyncIterator(channel)
      },
    }

module.exports = {
  deal,
}
Copy the code

Next, you’ll see a New Deal notification every 2 seconds:

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