zanith

Mixins & Reuse

Mixins are reusable field groups that eliminate repetition across your models. Instead of copy-pasting id, timestamps, and audit fields into every model, spread a mixin with one line.

The problem

Every model needs an ID. Most need timestamps. Many need audit trail fields or soft delete. Without mixins, you'd write the same 3-6 lines in every model. With 50+ models, that's hundreds of duplicated lines — and if you change the ID strategy, you change it everywhere.

Built-in mixins

Zanith provides these mixins out of the box. Use them with the spread syntax:

MixinWhat it addsFields created
...m.id()UUID primary keyid: uuid, primary, default(uuid())
...m.intId()Auto-increment integer PKid: int, primary, default(autoincrement())
...m.timestamps()Created + updated timestampscreatedAt: datetime default(now()), updatedAt: datetime autoUpdate
...m.auditable()Who created/updated this recordcreatedById: uuid nullable, updatedById: uuid nullable
...m.orgScoped()Multi-tenant foreign keyorganizationId: uuid with database index
...m.softDelete()Soft delete supportdeletedAt: datetime nullable

Using mixins

Spread mixins at the top of your fields, then add model-specific fields below. You can use any combination:

TSmodels/order.ts
const Order = defineModel((m) => ({
  name: 'Order',
  table: 'orders',
  fields: {
    ...m.id(),           // → id (uuid pk)
    ...m.timestamps(),   // → createdAt, updatedAt
    ...m.auditable(),    // → createdById, updatedById
    ...m.orgScoped(),    // → organizationId (indexed)
    ...m.softDelete(),   // → deletedAt (nullable)
 
    // Model-specific fields:
    total: m.float(),
    status: m.enum(OrderStatus).default('PENDING'),
    customerId: m.uuid().index(),
  },
}));

Custom mixins

Since the builder is plain TypeScript, creating custom mixins is just writing a function that returns an object of field builders. This is where Zanith's TypeScript-first approach shines — no special syntax, just functions.

TSmixins/address.ts
// Custom mixin: reusable address fields
export function addressFields(m) {
  return {
    street: m.string(),
    city: m.string(),
    state: m.string(),
    zip: m.string(),
    country: m.string().default('US'),
  };
}
 
// Use in any model:
const Customer = defineModel((m) => ({
  name: 'Customer', table: 'customers',
  fields: {
    ...m.id(),
    ...m.timestamps(),
    ...addressFields(m),    // ← reused across models
    name: m.string(),
    email: m.string().unique(),
  },
}));
 
const Warehouse = defineModel((m) => ({
  name: 'Warehouse', table: 'warehouses',
  fields: {
    ...m.id(),
    ...addressFields(m),    // ← same fields, different model
    capacity: m.int(),
  },
}));

Conditional mixins

Because mixins are just functions, you can use conditions:

TS
function tenantFields(m, { multiTenant = false }) {
  if (!multiTenant) return {};
  return {
    ...m.orgScoped(),    // only added when multi-tenant is enabled
  };
}
 
const Product = defineModel((m) => ({
  name: 'Product', table: 'products',
  fields: {
    ...m.id(),
    ...tenantFields(m, { multiTenant: true }),
    name: m.string(),
  },
}));