Custom Type

🔋 ZModel vs Prisma Schema

Custom type is a ZModel concept and doesn't exist in PSL.

Besides models, you can also define custom types to encapsulate complex data structures. The main difference between a model and a custom type is that the latter is not backed by a database table.

Here's a simple example:

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

Custom types are defined exactly like models. They can contain fields that are other custom types:

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

type UserProfile {
    gender  String
    address Address?
}

Relation Fields

Available since v3.6.0

Custom types can also contain relation fields to models. This is particularly useful when used as mixins to share relation field definitions across multiple models. For example, you can define an audit mixin that tracks who created and last updated a record:

type AuditMixin {
    id          String @id @default(cuid())
    createdBy   User    @relation("CreatedBy", fields: [createdById], references: [id])
    createdById String
    updatedBy   User    @relation("UpdatedBy", fields: [updatedById], references: [id])
    updatedById String
}

model Post with AuditMixin {
    title String
}

model Comment with AuditMixin {
    body String
}

warning

Custom types with relation fields can only be used as mixins. They cannot be used to type JSON fields, since JSON fields cannot hold relational data.

There are two ways to use custom types:

• Mixin
• Strongly typed JSON fields