Invalid inferred type for nested releations #28217

maxkrumpe · 2025-10-04T17:18:18Z

maxkrumpe
Oct 4, 2025

Question

I would like to create a type for the dynamic payload based on my selector to share its type at multiple places.

I have created the helper function:

export const getFestivalDaysSelect = (
   queries?: SelectFestivalDayQueryParams,
) => {
   return {
      id: true,
      date: true,
      festivalDayMeals: !queries?.includeMeals ? false : {
         select: {
            meal: true,
         },
      },
   } satisfies FestivalDaySelect;
};

export type Test = FestivalDayGetPayload<{
   select: ReturnType<typeof getFestivalDaysSelect>,
}>;

The issue is that the type is not inferred correctly because of the condition and will always define the type for "festivalDayMeals" to not contain the "meal".

The created type "Test" will look like:

{
   id: number
   date: Date
   festivalDayMeals: {
      id: number
      festivalDayId: number
      mealId: number
   }[]
}

If the condition is removed, the type will be inferred correctly and will contain "meal" in "festivalDayMeals":

export const getFestivalDaysSelect = (
   queries?: SelectFestivalDayQueryParams,
) => {
   return {
      id: true,
      date: true,
      festivalDayMeals: {
         select: {
            meal: true,
         },
      },
   } satisfies FestivalDaySelect;
};

export type Test = FestivalDayGetPayload<{
   select: ReturnType<typeof getFestivalDaysSelect>,
}>;

Here the created type "Test" will look like:

{
   id: number
   date: Date
   festivalDayMeals: {
      meal: {
         id: number
         name_de: string
         name_en: string
         canBeCombined: boolean
      }
   }[]
}

Is there a way to solve this issue or is it a bug?

How to reproduce (optional)

Expected behavior (optional)

The correct type should be returned for example something like:

{
   id: number
   date: Date
   festivalDayMeals?: {
      meal: {
         id: number
         name_de: string
         name_en: string
         canBeCombined: boolean
      }
   }[]
}

or

{
   id: number
   date: Date
} | {
   id: number
   date: Date
   festivalDayMeals: {
      meal: {
         id: number
         name_de: string
         name_en: string
         canBeCombined: boolean
      }
   }[]
}

Information about Prisma Schema, Client Queries and Environment (optional)

generator client {
  provider = "prisma-client"
  output   = "../src/generated/prisma"
  engineType = "library"
  runtime = "nodejs"
  moduleFormat = "cjs"
}

datasource db {
  provider = "postgresql"
  url      = env("POSTGRES_URL")
}

model FestivalDay {
  id               Int               @id @default(autoincrement())
  date             DateTime          @unique @db.Date
  festivalDayMeals FestivalDayMeal[]

  @@map("festival_days")
}

model Meal {
  id               Int               @id @default(autoincrement())
  name_de          String            @unique
  name_en          String            @unique
  canBeCombined    Boolean           @map("can_be_combined")
  festivalDayMeals FestivalDayMeal[]

  @@map("meals")
}

model FestivalDayMeal {
  id            Int         @id @default(autoincrement())
  festivalDayId Int         @map("festival_day_id")
  mealId        Int         @map("meal_id")
  festivalDay   FestivalDay @relation(fields: [festivalDayId], references: [id])
  meal          Meal        @relation(fields: [mealId], references: [id])

  @@map("festival_day_meals")
}

OS: macOS
Database: PostgreSQL
Node.js version: v22.14.0
Run prisma -v to see your Prisma version and paste it

prisma                  : 6.16.3
@prisma/client          : 6.16.1
Computed binaryTarget   : darwin-arm64
Operating System        : darwin
Architecture            : arm64
Node.js                 : v22.14.0
TypeScript              : 5.9.3
Query Engine (Node-API) : libquery-engine bb420e667c1820a8c05a38023385f6cc7ef8e83a (at node_modules/.pnpm/@[email protected]/node_modules/@prisma/engines/libquery_engine-darwin-arm64.dylib.node)
PSL                     : @prisma/prisma-schema-wasm 6.16.1-1.bb420e667c1820a8c05a38023385f6cc7ef8e83a
Schema Engine           : schema-engine-cli bb420e667c1820a8c05a38023385f6cc7ef8e83a (at node_modules/.pnpm/@[email protected]/node_modules/@prisma/engines/schema-engine-darwin-arm64)
Default Engines Hash    : bb420e667c1820a8c05a38023385f6cc7ef8e83a
Studio                  : 0.511.0

nurul3101 · 2025-10-06T10:14:23Z

nurul3101
Oct 6, 2025
Maintainer

Hi @maxkrumpe!

When you use a condition to optionally include a nested selection, Prisma cannot accurately infer the resulting payload type. Instead, it falls back to a less precise type.

This is discussed in detail in this issue and this issue.

For now, you can manually define a union or optional type that matches the possible payloads. There are a few workarounds mentioned in the linked issues as well.

0 replies

2025-10-14T00:32:24Z

github-actions[bot]
bot Oct 14, 2025

Hi,

As we have not heard back from you, we are closing this discussion to keep our discussions organized.

Feel free to start a new discussion if this remains relevant.

Thank you for being part of the community!

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maxkrumpe Oct 4, 2025

Question

How to reproduce (optional)

Expected behavior (optional)

Information about Prisma Schema, Client Queries and Environment (optional)

Replies: 2 comments

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nurul3101 Oct 6, 2025 Maintainer

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github-actions[bot] bot Oct 14, 2025

maxkrumpe
Oct 4, 2025

nurul3101
Oct 6, 2025
Maintainer

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bot Oct 14, 2025