Subscription syntax in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a GraphQL subscription?

A GraphQL subscription is a way to get real-time updates from the server. It keeps a connection open and sends data when something changes.

beginner

Basic syntax to start a subscription in GraphQL?

Use the subscription keyword followed by the subscription name and the fields you want to receive updates for.

intermediate

How do you specify which events to listen to in a subscription?

Inside the subscription, you specify the event or data field you want updates for, similar to a query but it listens continuously.

beginner

Example of a simple subscription for new messages?

subscription { newMessage { id content sender } } This listens for new messages and returns their id, content, and sender.

intermediate

Why use subscriptions instead of queries for real-time data?

Queries fetch data once. Subscriptions keep the connection open and send updates automatically when data changes, saving time and resources.

Which keyword starts a GraphQL subscription?

A query

B subscription

C mutation

D listen

The subscription keyword is used to start a subscription operation in GraphQL.

What does a subscription do?

A Fetches data once

B Updates data on the server

C Keeps connection open for real-time updates

D Deletes data

Subscriptions keep the connection open and send data updates in real-time.

Which of these is a valid subscription field selection?

A subscription { newMessage { id content } }

B query { newMessage { id content } }

C mutation { newMessage { id content } }

D listen { newMessage { id content } }

Subscriptions use the subscription keyword and specify fields to receive updates.

Subscriptions are best used for:

A One-time data fetch

B Batch processing

C Data deletion

D Real-time data updates

Subscriptions provide real-time updates by keeping the connection open.

Which statement is true about GraphQL subscriptions?

A They listen for events and send data continuously

B They use the same syntax as mutations

C They close the connection after one response

D They cannot specify fields to return

Subscriptions listen for events and send data continuously as changes happen.

Explain how to write a basic GraphQL subscription and what it does.

Think about how subscriptions differ from queries.

Describe why and when you would use a subscription instead of a query in GraphQL.

Consider the difference between one-time fetch and live updates.