Triggers

This is a component built for build-on-components-day.

What can you trigger

Run code whenever a table changes.

Example usages:

• Attach a custom index to a table, like a geospatial index or a BTree with aggregates.
• Log whenever the table changes.
• Detect unauthorized access with Row Level Security and throw an error.

How to use

Copy installation pattern from convex/triggers.ts.

Copy usage pattern from convex/messages.ts.

Each triggered function runs within the same mutation, immediately after the document write. If you want async triggers, you can use ctx.scheduler.runAfter(0, ...);

All of your functions that modify the table must be wrapped in mutationWithTriggers instead of mutation, in order to trigger the triggers. Triggers do not run when the table changes through a plain mutation or through the Convex Dashboard.

Triggers are called with arguments matching triggerArgsValidator, so you know whether it was an insert, patch, replace, or delete. You are also given the document ID and the full document contents before and after the write.

The usage of components allows the oldDoc and newDoc to be computed atomically, unlike the DatabaseWriter wrapper from the Row Level Security helpers.