[ClientExtensions, TypeScript] Fields of custom type aren't available when using the ClientExtensions preview-feature, unless select'd explicitly.

[ItzSiL3Nce]

Bug description

Only when the clientExtensions preview-feature is enabled (just by enabling it, no need to define custom extensions), fields of a user-defined custom type aren't available after querying the model, unless select'd explicitly.
Note: They are available at runtime, only TypeScript doesn't have them, I'm using the MongoDB as the db provider. Also, might be related to #17349, but not sure.

How to reproduce

Simply create a Prisma model that has one or more fields of an user-defined type. That field won't be available (TypeScript's types only, it is available at runtime) unless it was explicitly selectd. Full example shown below.

Expected behavior

Every field (TypeScript) should be available after executing a query, including the ones of custom types. Just like it is when not using the clientExtensions preview-feature.

Prisma information

schema.prisma

type CustomType {
  data         String
  otherThings  String
  // ...
}

model ExampleUser {
  id        String @id @default(auto()) @map("_id") @db.ObjectId
  username  String
  password  String
  // ...
  otherData CustomType?
}

Using the prisma client

import { PrismaClient } from '@prisma/client'

const client = new PrismaClient()

async function main() {
  await client.$connect()
  
  const userNotWorking = await client.exampleUser.findFirst({ 
    where: {
      username: 'test-user'
    } 
  })

 // @ts-expect-error : Here the `otherData` field is not present inside the `userNotWorking` object.
 const dataNotWorking = userNotWorking.otherData

 // To make it work, the query needs `select` to be added with all the fields wanted.
  const user = await client.exampleUser.findFirst({ 
    where: {
      username: 'test-user'
    },
   select: {
      otherData: true
   }
  })


 // Here the `otherData` field is present inside the `user` object.
 const data = user.otherData
}

main()
  .catch(console.error)
  .finally(() => {
    client.$disconnect()
  })

Environment & setup

• OS: Ubuntu
• Database: MongoDB
• Node.js version: Both 14.20.0 and 18.13.0 (LTS)
• Preview Features: clientExtensions
• Typescript: 4.9.4

Prisma Version

prisma                  : 4.9.0
@prisma/client          : 4.9.0
Current platform        : debian-openssl-3.0.x
Query Engine (Node-API) : libquery-engine ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../../node_modules/@prisma/engines/libquery_engine-debian-openssl-3.0.x.so.node)
Migration Engine        : migration-engine-cli ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../../node_modules/@prisma/engines/migration-engine-debian-openssl-3.0.x)
Introspection Engine    : introspection-core ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../../node_modules/@prisma/engines/introspection-engine-debian-openssl-3.0.x)
Format Binary           : prisma-fmt ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5 (at ../../node_modules/@prisma/engines/prisma-fmt-debian-openssl-3.0.x)
Format Wasm             : @prisma/prisma-fmt-wasm 4.9.0-42.ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5
Default Engines Hash    : ceb5c99003b99c9ee2c1d2e618e359c14aef2ea5
Studio                  : 0.479.0
Preview Features        : clientExtensions

[millsp]

Thanks for the report! I can confirm this as we were conscious that in this first iteration we wouldn't yet support MongoDB's composite types.

[pheuter]

This issue is currently preventing me from trying out my early access to Prisma Accelerate (since it requires enabling client extensions), looking forward to client extensions supporting composite types 👀