Hey all. Looking for some help here. I am trying to implement a polymorphic relation in prisma with postgresql. I have the following models • User : a user • App : an App • Dateset: a Datasets • Collaborator: A user with permissions to edit, view etc either an App or a Dataset I have tried to set this up two different ways. First, the simpler looks like

enum ResourceType {
  App
  Dataset
}

model App {
  id            String         @id @default(cuid())
  spec          Json
  createdAt     DateTime       @default(now())
  updatedAt     DateTime       @default(now())
  name          String
  description   String
  public        Boolean
  ownerId       String
  noViews       Int            @default(0)
  noForks       Int            @default(0)
  owner         User           @relation(fields: [ownerId], references: [id])
  collaborators Collaborator[] @relation("AppColaborator")

  @@map("apps")
}

model Dataset {
  id            String         @id @default(cuid())
  createdAt     DateTime       @default(now())
  name          String
  description   String
  public        Boolean
  path          String
  ownerId       String
  owner         User           @relation(fields: [ownerId], references: [id])
  collaborators Collaborator[] @relation("DatasetColaborator")

  @@map("datasets")
}


model User {
  id             String         @id @default(cuid())
  name           String?
  apps           App[]
  collaborations Collaborator[]
  Datasets       Dataset[]
  @@map("users")
}


model Collaborator {
  id           String       @id @default(cuid())
  user         User         @relation(fields: [userId], references: [id])
  userId       String
  appId        String?
  datasetId    String?
  resourceType ResourceType
  view         Boolean
  edit         Boolean
  manage       Boolean
  app          App?         @relation("AppColaborator", fields: [appId], references: [id], map: "app_colaboration_id")
  dataset      Dataset?     @relation("DatasetColaborator", fields: [datasetId], references: [id], map: "dataset_colaboration_id")

  @@unique([userId, appId, datasetId])
  @@map("collaborators")
}

The issue with this is if I try and create or upsert a Collaborator object, I cant because one of the appId or datasetId needs to be undefined which prisma rejects. The other approach I have tried is to have a single resourceId with a resourceType that defines what kind of resource this is and define two relationships like so

model Collaborator {
  id           String       @id @default(cuid())
  user         User         @relation(fields: [userId], references: [id])
  userId       String
  resourceId   String
  resourceType ResourceType
  view         Boolean
  edit         Boolean
  manage       Boolean
  app          App?         @relation("AppColaborator", fields: [resourceId], references: [id], map: "app_colaboration_id")
  dataset      Dataset?     @relation("DatasetColaborator", fields: [resourceId], references: [id], map: "dataset_colaboration_id")
  @@unique([userId, resourceId])
  @@map("collaborators")
}

However that fails when I try to create a new collaborator because both foreign key constraints for datasetId and appId cant both be satisfied. Is there a good model or example for doing this kind of thing? A little stumped here

Hi @stuart Lynn 👋 At the moment Prisma doesn't have support for Polymorphic association. However there is a feature request in that regard. You might want to add your usecase there.

Will do thanks!

You're welcome