How to infer output based on select in relational queries?

[jansedlon]

Hello,

I have this helper for prisma in my repo

export async function requireAdmin<A extends Record<string, unknown>>(
  request: Request,
  options?: Prisma.Exact<A, Prisma.Args<typeof prisma.user, "findFirst">>,
): Promise<Exclude<Prisma.Result<typeof prisma.user, A, "findFirst">, null>> {
  return requireUserWithRole(UserRole.ADMIN, request, options);
}

When calling this function i have autocomplete for prisma options that are passed to a query. It's also able to infer the output. So when i pass { select: { id: true }} it returns { id: string } based on the query/model.

Is there anything similar in drizzle? I tried to build it myself but so far unsuccessfully due to the complexity of the RelationalQueryBuilder

What i wanna be able to do is something like

const store =await getStoreByUserId(userId, {
  columns: {
    id: true,
  },
  with: {
    something: {
      columns: { id: true }
    }
  },
})

And the output should match what i would expect.

PS: I asked claude and it.. Actually made it work, do you think it's a viable solution?

// First, let's define a utility type to extract the first type parameter of a function
type ExtractFirstTypeParam<T> = T extends (config?: infer U) => any ? U : never;

// Now, let's create a type to extract the extends clause from a conditional type
type ExtractExtendsClause<T> = T extends infer U extends any ? U : never;

// Putting it all together
type ExtractConfigType<T> = ExtractExtendsClause<ExtractFirstTypeParam<T>>;

type ExtractedType = ExtractConfigType<typeof db.query.users.findFirst>


function a<T extends ExtractedType>(options: T): Promise<ReturnType<typeof db.query.users.findFirst<T>>> {
  return db.query.users.findFirst(options) as any
}

// Has the correct type
const c = await a({
  columns: {
    id: true,
  },
  with: {
    stores: true,
  }
})