Conditional uniqueness constraints

Problem

I would like to be able to define a uniqueness constraint that has conditional elements to it so that it can map to and align with a conditional unique index/constraint within the database.

Suggested solution

Modify the @@unique modifier to include a where: { } argument that could define the condition that allows this to be unique.

[ArthurThornton]

One example of how this might be used would be a model of phone numbers for a user, where we have a field to determine which one is the primary number:

model PhoneNumber {
  (standard id/created/updated fields)

  userId    String  @map("user_id")
  user      User    @relation(fields: [userId], references: [id])
  number    String
  isPrimary Boolean @map("is_primary")

  @@unique([userId, isPrimary], name: "uniquePrimaryForUser", where: { isPrimary: true })
  @@unique([userId, number], name: "uniqueNumberForUser")
}

In postgres, they support unique indexes with conditions. For this example, you’d create the index with:

CREATE UNIQUE INDEX phone_number_unique_primary_for_user ON "PhoneNumber"(user_id, is_primary) WHERE (is_primary = true);

This is possible within Rails’ ActiveRecord validations, which I’ve used in the past, and something I would derive great value from also getting within Prisma.

[vthang95]

Any update on this issue? Very surprised that this is common but unimplemented yet.

This proposal is okay:

@@unique([slug, isPublished], name: "uniquePublishedPostSlug", where: { isPublished: true })

or

@@unique([slug, isPublished], name: "uniquePublishedPostSlug", where: "isPublished = true")