How to create multiple relationships to the same filed in prisma

Question

Here Is the related portion of my datamodel.prisma file.

type Driver {
  id: ID! @unique
  zones: [Zone!] @relation(name: "DriverZones")
  shifts: [Shift!] @relation(name: "DriverShifts")
  preferredZone: Zone
  preferredShift: Shift
}


type Shift {
  id: ID! @unique 
  drivers: [Driver! ] @relation(name: "DriverShifts") 
}


type Zone {
  id: ID! @unique 
  drivers: [Driver! ] @relation(name: "DriverZones") 
}

Here I want to create the relationship for preferredZone and preferredShift to be type Zone and Shift according to the datamodel I have created. this is a one way relationship.

The relation field preferredShift must specify a @relation directive: @relation(name: "MyRelation") , The relation field preferredZone must specify a @relation directive: @relation(name: "MyRelation")

I'm using PostgreSQL for my prisma database. How to build the relationship between preferredZone to Zone. and preferredShift to Shift.

Answer 1

This section from prisma docs is relevant here:

When you define two relations between the same two models, you need to add the name argument in the @relation attribute to disambiguate them. As an example for why that's needed, consider the following models:

// NOTE: This schema is intentionally incorrect. See below for a working solution.

model User {
  id           Int     @id @default(autoincrement())
  name         String?
  writtenPosts Post[]
  pinnedPost   Post?
}

model Post {
  id         Int     @id @default(autoincrement())
  title      String?
  author     User    @relation(fields: [authorId], references: [id])
  authorId   Int
  pinnedBy   User?   @relation(fields: [pinnedById], references: [id])
  pinnedById Int?
}

In that case, the relations are ambiguous, there are four different ways to interpret them:

• User.writtenPosts ↔ Post.author + Post.authorId
• User.writtenPosts ↔ Post.pinnedBy + Post.pinnedById
• User.pinnedPost ↔ Post.author + Post.authorId
• User.pinnedPost ↔ Post.pinnedBy + Post.pinnedById

To disambiguate these relations, you need to annotate the relation fields with the @relation attribute and provide the name argument. You can set any name (except for the empty string ""), but it must be the same on both sides of the relation:

model User {
  id           Int     @id @default(autoincrement())
  name         String?
  writtenPosts Post[]  @relation("WrittenPosts")
  pinnedPost   Post?   @relation("PinnedPost")
}

model Post {
  id         Int     @id @default(autoincrement())
  title      String?
  author     User    @relation("WrittenPosts", fields: [authorId], references: [id])
  authorId   Int
  pinnedBy   User?   @relation("PinnedPost", fields: [pinnedById], references: [id])
  pinnedById Int?    @unique
}

Answer 2

I would like you to try this way:

model User {
  id            String    @id @default(cuid())
  name          String?
  email         String?   @unique
  emailVerified DateTime?
  image         String?
  accountId     String    @unique

  account Account @relation(fields: [accountId], references: [id])

  sessions       Session[]
  TeamHasMembers TeamHasMembers[]
  TeamHasLeaders TeamHasLeaders[]
}

model Team {
  id   String @id @default(cuid())
  name String
  slug String @unique

  TeamHasMembers TeamHasMembers[]
  TeamHasLeaders TeamHasLeaders[]
}

model TeamHasMembers {
  id     String @id @default(cuid())
  userId String
  teamId String
  role   String

  user User @relation(fields: [userId], references: [id])
  team Team @relation(fields: [teamId], references: [id])
}

model TeamHasLeaders {
  id     String @id @default(cuid())
  userId String
  teamId String

  user User @relation(fields: [userId], references: [id])
  team Team @relation(fields: [teamId], references: [id])
}

Answer 3

You need to name the relations since you have two relations between same types (Driver <-> Shift and Driver <-> Zone both are connected by two relations each).

In cases like this Prisma asks you to name the relations which is what the error message you posted is about. I think this data model should work:

type Driver {
  id: ID! @unique
  zones: [Zone!] @relation(name: "DriverZones")
  shifts: [Shift!] @relation(name: "DriverShifts")
  preferredZone: Zone @relation(name: "PreferredZone")
  preferredShift: Shift @relation(name: "PreferredShift")
}


type Shift {
  id: ID! @unique 
  drivers: [Driver! ] @relation(name: "DriverShifts") 
}


type Zone {
  id: ID! @unique 
  drivers: [Driver! ] @relation(name: "DriverZones") 
}