Live Queries

Live Queries are the foundation of reactive applications built with Ramify JS. Instead of performing one-off data fetches, Live Queries allow your application to observe specific collections and automatically react to changes.

The Mechanism

At its core, Ramify JS uses an observer pattern on every collection. When a write operation (add, put, update, delete, or clear) occurs, the collection emits an event containing the affected primary keys.

Live Query implementations (like React hooks or custom observers) listen to these events to determine when a result set might have changed, triggering a re-execution of the query.

// Users subscription
const unsubscribeUsers = db.users.subscribe((type, keys) => {
	/* handle users update */
});

// Posts subscription
const unsubscribePosts = db.posts.subscribe((type, keys) => {
	/* handle posts update */
});

// Later, to unsubscribe
unsubscribeUsers();
unsubscribePosts();

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Platform Integration

While the core mechanism is platform-agnostic, most users will interact with Live Queries through framework-specific integrations.

React Integration

For React applications, Ramify JS provides a dedicated package @ramifyjs/react-hooks which includes the useLiveQuery hook. This hook handles subscription lifecycle, dependency tracking, and component re-renders automatically. Visit the React Hooks API documentation for more details.

Custom Observers

If you are using Ramify JS without a specialist framework integration, you can use the low-level Collection Subscription API to build your own reactive logic.

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Best Practices

• Stability: Ensure your query functions are stable (defined outside components or memoized) to prevent unnecessary re-subscriptions.
• Granular Dependencies: Only subscribe to the collections that are actually being queried to minimize overhead.
• Batching: Use bulk operations to group multiple changes into a single notification, reducing the number of reactive updates.