mixin.md

sidebar_position	8
description	Reusing common fields with mixins

import ZModelVsPSL from '../_components/ZModelVsPSL';

Mixin

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

:::info Mixin was previously known as "abstract inheritance" in ZenStack v2. It's renamed and changed to use the with keyword to distinguish from polymorphic model inheritance. :::

Very often you'll find many of your models share quite a few common fields. It's tedious and error-prone to repeat them. As a rescue, you can put those fields into custom types and "mix-in" them into your models.

Before:

model User {
    id        String   @id
    createdAt DateTime @default(now())
    updatedAt DateTime @updatedAt
    email     String   @unique
}

model Post {
    id        String   @id
    createdAt DateTime @default(now())
    updatedAt DateTime @updatedAt
    title     String
}

After:

type BaseFieldsMixin {
    id        String   @id
    createdAt DateTime @default(now())
    updatedAt DateTime @updatedAt
}

model User with BaseFieldsMixin {
    email String @unique
}

model Post with BaseFieldsMixin {
    title String
}

A model can use multiple mixins as long as their field names don't conflict.

Mixins don't exist at the database level. The fields defined in the mixin types are conceptually inlined into the models that use them.