Support for Yarn 2+ with PnP

When trying to run prisma2 init via yarn dlx it fails in the following way:

Getting the same behavior when having installed prisma2 as a local dev dependency:

I’m using yarn 2.0.0-rc.27

[dgattey]

Thank you @Globolobo + @darioblanco for putting me on the right path! I compiled this year-of-2022 note since no one suggestion above worked perfectly for me with Next + Vercel + Yarn 3 + Yarn PnP + Yarn Zero Install. Here’s my setup.

---

In package.json I use pnpify with a script to wrap generation. I also run generation as part of my yarn build. Nothing fancy with module resolution needed.

"scripts": {
    "build": "yarn db:generate && next build",
    "db:generate": "yarn pnpify prisma generate",
},
"dependencies": {
    "@prisma/client": "3.8.1",
},
"devDependencies": {
    "@yarnpkg/pnpify": "^3.1.1-rc.12",
    "prisma": "3.8.1",
  },

In my prisma/schema.prisma, I set a relative output path (this can be anything, I’m just putting it into my server api folder). It just needs to be within src.

generator client {
  provider = "prisma-client-js"
  output   = "../src/api/server/generated"
}

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

I make sure to ignore that path for version control (and prettier/eslint/anything else) in .gitignore/etc

# Generated files from Prisma
src/api/server/generated

And finally, in my .ts files, I just import from my custom path instead of from the main package. Works great!

import { PrismaClient } from 'api/server/generated/';
const dbClient = new PrismaClient();

or

import type { Prisma } from 'api/server/generated/'';

---

Notes

1. If your package resolution requires a relative path like ../../api/... or a prefix like @app/api/..., that should work fine instead, I just use api/... directly since I set that up as a top level path.

2. You could avoid putting the generate command in your build command if you check the generated folder into version control, but I didn’t think that was worth it. If you don’t check it in, then Vercel/whatever will fail the build since it’ll be missing until you run generation again. As my DB should always be up and accessible, I see no problem with generating from Vercel before I build. Catches breaking changes anyway.

[matthewmueller]

Quick update

We’d like to add support for Yarn 2, but not right now. Yarn 2 is a significant departure from other Node package managers (no node_modules!). By default, Prisma Client relies on the presence of node_modules, so we need to figure out how to first detect Yarn 2 and then apply a Yarn 2-specific solution.

This is all totally doable, but it will just take time. Right now we’re focused on adding more powerful query features to the Prisma Client.

PRs to fix this are very welcome of course!

Workaround

In the meantime, you can workaround this issue by providing a custom output path.

prisma/schema.prisma

generator client {
  provider = "prisma-client-js"
  // Output to a custom location
  output   = "../generated/client"
}

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

model User {
  id      Int      @default(autoincrement()) @id
  email   String   @unique
  name    String?
  posts   Post[]
  profile Profile?
}

main.ts

// Include the client from a custom location
import { PrismaClient } from './generated/client'

async function main() {
  const client = new PrismaClient()
  const data = await client.user.findMany()
  console.log(data)
  client.disconnect()
}

main().catch(console.error)

You can read more about this feature here: https://www.prisma.io/docs/reference/tools-and-interfaces/prisma-client/generating-prisma-client#specifying-a-custom-output-path