vercel__next.js/examples/cms-payload/payload/payloadClient.ts

import { getPayload } from "payload/dist/payload";
import config from "./payload.config";

if (!process.env.MONGODB_URI) {
  throw new Error("MONGODB_URI environment variable is missing");
}

if (!process.env.PAYLOAD_SECRET) {
  throw new Error("PAYLOAD_SECRET environment variable is missing");
}

/**
 * Global is used here to maintain a cached connection across hot reloads
 * in development. This prevents connections growing exponentially
 * during API Route usage.
 *
 * Source: https://github.com/vercel/next.js/blob/canary/examples/with-mongodb-mongoose/lib/dbConnect.ts
 */
let cached = (global as any).payload;

if (!cached) {
  cached = (global as any).payload = { client: null, promise: null };
}

export const getPayloadClient = async () => {
  if (cached.client) {
    return cached.client;
  }

  if (!cached.promise) {
    cached.promise = await getPayload({
      // Make sure that your environment variables are filled out accordingly
      mongoURL: process.env.MONGODB_URI as string,
      secret: process.env.PAYLOAD_SECRET as string,
      config: config,
    });
  }

  try {
    cached.client = await cached.promise;
  } catch (e) {
    cached.promise = null;
    throw e;
  }

  return cached.client;
};

export default getPayloadClient;