Wrong typing when trying to connect models with a unique constraint on an optional field

[vdhpieter]

Bug description

We have a model that has an optional field that has to be unique. When trying to use the connect keyword we get a TS error that the optional field does not have the right type.

A full reproduction repo can be found here: https://github.com/vdhpieter/prisma-partial-uniqueness-bug

How to reproduce

These reproductions start from a reproduction repo after following: https://www.prisma.io/docs/getting-started/quickstart

1. Make the optional name field unique in your schema for the User model:

https://github.com/vdhpieter/prisma-partial-uniqueness-bug/blob/c23577bc4a6050d6132f032a45b2ccb63ebd7f45/prisma/schema.prisma#L16

2. Create an user

https://github.com/vdhpieter/prisma-partial-uniqueness-bug/blob/c23577bc4a6050d6132f032a45b2ccb63ebd7f45/script.ts#L6-L8

3. Create a Post and connect it to the previously created user

https://github.com/vdhpieter/prisma-partial-uniqueness-bug/blob/c23577bc4a6050d6132f032a45b2ccb63ebd7f45/script.ts#L10-L13

4. See the following TS error (also visible when running npm run start)

https://github.com/vdhpieter/prisma-partial-uniqueness-bug/blob/c23577bc4a6050d6132f032a45b2ccb63ebd7f45/script.ts#L14-L21

Expected behavior

I can use connect with models that have optional unique fields.

Prisma information

generator client {
  provider = "prisma-client-js"
}

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

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

model Post {
  id        Int     @id @default(autoincrement())
  title     String
  content   String?
  published Boolean @default(false)
  author    User    @relation(fields: [authorId], references: [id])
  authorId  Int
}

  const user = await prisma.user.create({
    data: { email: "new-user@prisma.io" },
  });

  prisma.post.create({
    data: {
      title: "A Very good post",
      author: { connect: user },
    },
  });

Environment & setup

• OS: macOS
• Database: SQLite
• Node.js version: 20.7.0

Prisma Version

prisma                  : 5.13.0
@prisma/client          : 5.13.0
Computed binaryTarget   : darwin-arm64
Operating System        : darwin
Architecture            : arm64
Node.js                 : v20.7.0
Query Engine (Node-API) : libquery-engine b9a39a7ee606c28e3455d0fd60e78c3ba82b1a2b (at node_modules/@prisma/engines/libquery_engine-darwin-arm64.dylib.node)
Schema Engine           : schema-engine-cli b9a39a7ee606c28e3455d0fd60e78c3ba82b1a2b (at node_modules/@prisma/engines/schema-engine-darwin-arm64)
Schema Wasm             : @prisma/prisma-schema-wasm 5.13.0-23.b9a39a7ee606c28e3455d0fd60e78c3ba82b1a2b
Default Engines Hash    : b9a39a7ee606c28e3455d0fd60e78c3ba82b1a2b
Studio                  : 0.500.0

[vdhpieter]

@SevInf thanks for the correct labels, is there something I can do to help move this issue forward? I don't think I have the understanding of the prisma repo to solve it myself but happy to help where I can!

[SevInf]

@vdhpieter I haven't actually tried running your code but from your snippet, i can make a guess:

connect field accepts only id field, not complete user object. TS probably complains exactly about that: there are extra properties in connect which it does not recognize. Try changing your code to:

prisma.post.create({
    data: {
      title: "A Very good post",
      author: { connect: { id: user.id }} },
    },
  });

[vdhpieter]

@SevInf thanks for the clarification. I think I was confused because of the fact that it does work most of the time! Thanks for the explenation!