Allow Relations in Model Extension needs Dependencies

[defrex]

Problem

The new extensions feature is great! My team is already using it for a few things.

However, we'd love to add computed props based on relationships.

Here is a simple example. Given these models

model Account {
  id           Int           @id @default(autoincrement())
  transactions Transaction[]
}

model Transaction {
  id        Int      @id @default(autoincrement())
  amount    Int
  account   Account? @relation(fields: [accountId], references: [id])
  accountId Int?
}

I'd like to add balance as a computed property of Account

prisma.$extends({
  result: {
    account: {
      balance: {
        needs: {
          transactions: true, // <- Type 'boolean' is not assignable to type 'never'.
        },
        compute(account) {
          return sumBy(account.transactions, "amount");
        },
      },
    },
  },
});

Suggested solution

Allow requiring certain relations to be include'd in order to compute a prop.

Alternatives

The alternative I'm currently considering is overwriting query to dynamically add the fields (or maybe a wrapper-class) if the relations are present.

The problem with that approach is that the types won't be correct.

[SevInf]

Hi @defrex!
Thank you for kind words and for opening this request. We plan to eventually implement it (sorry, no ETA yet) and we already have a separate issue for tracking that. I am going to close this as a duplicate. You can follow the progress in #20091