Problem

Unions data types are handy in features like feeds. Right now it's difficult to model unions in Prisma and it would be great if we could make this feature higher-level.

You'll also find community use cases in this thread.

Possible solution

Facebook's feed is a good example. The feed has Videos, Photos and Posts.

Modeled in Typescript

type Activity = Video | Photo | Message

type Video = {
  type: 'video'
  url: string
  media: 'webm' | 'mp4'
}

type Photo = {
  type: 'photo'
  width: number
  height: number
}

type Post = {
  type: 'post'
  message: string
}

Modeled in Postgres

create sequence bigserial activity_id;

create table videos (
  id activity_id primary key,
  url text not null,
  media text not null
)

create table photos (
  id activity_id primary key,
  width int,
  height int
)

create table posts (
  id activity_id primary key,
  message text
)

Alternatives

There are lots of alternative table inheritance schemes. We'd need to weigh the pros and cons of each.