Prisma many-to-many query not properly structuring data

[demacericcardo]

I can't get the data from a many to many relation in a proper way. I got the relation: USER-EVENT

Prisma query:

await this.prisma.event.findUnique({ where: { id: eventId }, include: { users: { select: { user: true } } } })

The data appears double nested:

[millsp]

Hey @demacericcardo, could you please share the following with us?

• Your schema
• Node.js version
• Prisma version
• Some code for reproducing this

That would be helpful for us to be able to look into it. Thanks!

[demacericcardo]

My schema:

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

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

model User {
id Int @id @default(autoincrement())
createdAt DateTime @default(now())
updatedAt DateTime @updatedAt

username String @unique
email String
passwordHash String

name String
surname String
birthDate DateTime
profilePic String

roles Role[]
events UsersOnEvents[]
}

model Event {
id Int @id @default(autoincrement())
createdAt DateTime @default(now())
updatedAt DateTime @updatedAt

eventDate DateTime
title String
description String?
image String?

users UsersOnEvents[]
}

model UsersOnEvents {
user User @relation(fields: [userId], references: [id], onDelete: Cascade, onUpdate: Cascade)
userId Int
event Event @relation(fields: [eventId], references: [id], onDelete: Cascade, onUpdate: Cascade)
eventId Int
assignedAt DateTime @default(now())

@@id([userId, eventId])
}

enum Role {
User
Admin
}`

Node version: 16.16.0

Prisma version:
prisma : 4.3.0
@prisma/client : 4.3.1

The code is the same I already posted:

await this.prisma.event.findUnique({ where: { id: eventId }, include: { users: { select: { user: true } } } })

[millsp]

Thanks. The result data/structure seems expected to me, why is it unexpected for you?

[demacericcardo]

I was expecting the query not including the data from the many to many table but just an array of the referenced users, how can i do that? if there's a way

[millsp]

If I understood well, you want the nested result as a top result? That's not possible. You'd need to get it yourself by accessing the nested properties.

[demacericcardo]

Ok, no problem. Thank you

[luminous8]

If I understood well, you want the nested result as a top result? That's not possible. You'd need to get it yourself by accessing the nested properties.

What's the best way to achieve that when quering multiple times the same field with a many-to-many relationship? @millsp
Could a middleware work to achieve what's suggested in this article automatically?

I'm refering to this block of code

const result = posts.map((post) => {
  return { ...post, tags: post.tags.map((tag) => tag.tag) }
})

[demacericcardo]

Yeah i was about to cycle the data and restructure the object before using it, my issue was about if there was a better way with just a single query.
Thank you anyway

[millsp]

What's the best way to achieve that when quering multiple times the same field with a many-to-many relationship? @millsp
Could a middleware work to achieve what's suggested in this article automatically?

Middleware can do that. However, be aware that you'd lose type-safety. That might be ok if that isn't a requirement.

[millsp]

@luminous8 @demacericcardo See https://www.prisma.io/docs/concepts/components/prisma-client/relation-queries#fluent-api