prisma: `ENOENT` with custom output and ESM module in NPM monorepo (including Nextjs): `no such file or directory, open /.../schema.prisma...`

Bug description

I’ve been seeing a slew of issues involving using Prisma-based local packages in an NPM monorepo with Nextjs, and I’ve encountered a case I could not solve using the existing solutions.

As a recap of the other issues, it seems when using a Prisma-based package (i.e. a package that ships with its own prisma.schema) in Nextjs, the resulting webpack bundles will look for schema.prisma relative to the directory of the bundle rather than the directory of the package dist. This results in errors like this:

Error: ENOENT: no such file or directory, open '/.../.next/cache/webpack/client-development/schema.prisma'

Now there have been some proposed solutions thus far, but the big difference is my package is an ESM package whereas the ones in the previous issues have been CJS packages. For example, one of the workarounds proposed here says to modify the Next config to use webpack externals and outputFileTracingRoot like so:

module.exports = {
  output: 'standalone',
  experimental: {
    outputFileTracingRoot: path.join(__dirname, '../../'),
  },
  webpack: (config, { buildId, dev, isServer, defaultLoaders, webpack }) => {
    config.externals = [...config.externals, '<PACKAGE>']

    return config
  },
}

However, if <PACKAGE> is an ESM module, this means webpack never transpiles it to CJS, resulting in a Error: require() of ES Module error when you try using the package in a Nextjs app. Hence, this fix does not work for ESM-based packages.

How to reproduce

I have created a repro repo here: https://github.com/slimshreydy/prisma-monorepo-esm-output-bug. See the README for instructions on local setup.

Expected behavior

Importing a package that uses prisma in Nextjs should look for the schema.prisma file in the package’s dist directory rather than the .next/ folder.

Prisma information

generator client {
  provider = "prisma-client-js"
  output = "./client"
}

datasource db {
  provider = "mysql"
  url      = env("DATABASE_URL")
}

model User {
  id        Int      @id @default(autoincrement())
  email     String   @unique
  createdAt DateTime @default(now())
}

import { NextApiRequest, NextApiResponse } from "next";
import { prisma } from "@prisma-monorepo-esm-output-bug/package/dist";

export default async (req: NextApiRequest, res: NextApiResponse) =>
  res.json(await prisma.user.findMany());

Environment & setup

• OS: macOS 10.15
• Database: PlanetScale
• Node.js version: v18.12.1

Prisma Version

prisma                  : 4.9.0
@prisma/client          : 4.9.0
Current platform        : darwin
Query Engine (Node-API) : libquery-engine ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../node_modules/@prisma/engines/libquery_engine-darwin.dylib.node)
Migration Engine        : migration-engine-cli ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../node_modules/@prisma/engines/migration-engine-darwin)
Introspection Engine    : introspection-core ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../node_modules/@prisma/engines/introspection-engine-darwin)
Format Binary           : prisma-fmt ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../node_modules/@prisma/engines/prisma-fmt-darwin)
Format Wasm             : @prisma/prisma-fmt-wasm 4.9.0-42.ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5
Default Engines Hash    : ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5
Studio                  : 0.479.0