Prisma extension that will automatically disconnect the Prisma client after a period of inactivity.

prisma-extension-idle-disconnect.ts

import { Prisma, PrismaClient } from '@prisma/client';

type PrismaClientWithQueryLogEvents = PrismaClient<{
  log: {
    level: 'query';
    emit: 'event';
  }[];
}>;

type PrismaClientIdleDisconnectEx = {
  $$idleDisconnectTimeoutId?: NodeJS.Timeout;
};

/**
 * Prisma extension that will automatically disconnect the Prisma client after a period of inactivity.
 *
 * **NOTE:** This extension requires you configure your PrismaClient to emit query log events.
 *
 * ```ts
 * // Example setup:
 * export const prisma = new PrismaClient({
 *   log: [{ level: 'query', emit: 'event' }],
 * }).$extends(prismaUtils.idleDisconnect);
 *
 * prisma.$configureIdleDisconnect(5 * 60000);
 * ```
 *
 * Also confirm you've opted into extensions in your `schema.prisma` file:
 * ```
 * generator client {
 *   provider        = "prisma-client-js"
 *   previewFeatures = ["clientExtensions"]
 *   // ...
 * }
 * ```
 *
 */
export const idleDisconnect = Prisma.defineExtension({
  client: {
    $configureIdleDisconnect(idleDisconnectTimeoutMs: number, debug = false) {
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
      const log = (...vals: any) => {
        debug && console.log('[idleDisconnect][DEBUG]', ...vals);
      };

      // Get current prisma instance and extend with typing specific to this extension
      const prisma = Prisma.getExtensionContext(this);
      const prismaEx = prisma as unknown as typeof prisma & {
        $on: PrismaClientWithQueryLogEvents['$on'];
      } & PrismaClientIdleDisconnectEx;

      prismaEx.$on('query', (e) => {
        log(`Prisma 'query' log triggered:`, e);

        // For each call to the Prisma client numerous 'query' events are emitted. The last one is the COMMIT query.
        if (e.query === 'COMMIT') {
          log('COMMIT query detected');

          if (prismaEx.$$idleDisconnectTimeoutId) {
            log('Clearing existing idle disconnect timeout');
            clearTimeout(prismaEx.$$idleDisconnectTimeoutId);
          }

          log(
            `Creating an idle disconnect timeout for ${idleDisconnectTimeoutMs}ms from now`,
          );
          prismaEx.$$idleDisconnectTimeoutId = setTimeout(() => {
            log('Disconnecting Prisma client');
            prismaEx.$disconnect(); // No await here, but fire-and-forget should be fine
          }, idleDisconnectTimeoutMs);
        }
      });
    },
  },
});