Strongly Typed JSON

🔋 ZModel vs Prisma Schema

Strongly typed JSON is a ZModel feature and doesn't exist in PSL.

With relational databases providing better and better JSON support, their usage has become more common. However, in many cases your JSON fields still follow a specific structure, and when so, you can make the fields strongly typed so that:

• When mutating the field, its structure is validated.
• When querying the field, its result is strongly typed.

To type a JSON field, define a custom type in ZModel, use it as the field's type, and additionally mark the field with the @json attribute.

Before:

model User {
    id      Int @id
    address Json
}

After:

type Address {
    street  String
    city    String
    country String
    zip     Int
}

model User {
    id      Int     @id
    address Address @json
}

info

The @json attribute doesn't do anything except to clearly mark the field is a JSON field but not a relation to another model.

The migration engine still sees the field as a plain Json field. However, the ORM client enforces its structure and takes care of properly typing the query results. We'll revisit the topic in the ORM part.