Allow field default to reference other fields

Problem

I have a model where there is the concept of a unique name and a displayName. Think GitHub organizations. I would like to encode in the model that the default for the displayName field is name field.

Suggested solution

An expression that references another non-nullable field whose type is the same.

model Workspace {
  kind        WorkspaceKind @default(workspace)
  id          String        @id @default(uuid())
  name        String        @unique
  displayName String        @default(field(name))        // <-- example
  members     User[]
}

Alternatives

It is easy to encode this at the application layer.

Additional context

This is a NTH (nice to have). The theme is encoding as much as possible at the database layer so that the application layer is easier to reason about.

[do4gr]

I had a quick look whether the new arbitrary sql in @default(dbgenerated()) would allow that. It seems that Postgres and Mysql do not directly support that in the default definition. So we’d indeed need a completely new feature for this.

[leafyshark]

Hi guys, is this something you decided to progress? I have two fields:

endTime: DateTime (which would be some day in the future) 24HoursAheadOfEndTime: DateTime @default(dbgenerated("NOW() + INTERVAL '1 DAY'"))

And I would like to replace NOW() with endTime field, is this possible at all or not?