Object types

An object type defines the properties and relationships shared by one kind of thing in your domain. Each object of that type has its own identity and values.

Define a type

Export a defineObjectType() definition from ontology/. This example uses the Customer type from the overview, placed in ontology/customer.ts:

// ontology/invoice.ts
import { defineObjectType, link, prop, stringEnum } from "@sixb/core/ontology"
import { Customer } from "./customer"

export const Invoice = defineObjectType({
  id: "Invoice",
  name: "Invoice",
  properties: [
    prop("id", "string", { required: true, primary: true }),
    prop("number", "string", { required: true }),
    prop("status", stringEnum(["draft", "sent", "paid"])),
  ],
  links: [link("customer", Customer, { cardinality: "one" })],
})

Use domain names such as Invoice or Satellite. Keep type and property IDs stable; display names can change independently.

Give objects an identity

Every type must have exactly one primary property. It must use the "string" schema with both required: true and primary: true:

prop("id", "string", { required: true, primary: true })

The property does not have to be named id. Its value identifies one object within the type: Invoice and Customer can each have an object with ID 001.

Reference properties and links

Definitions expose typed references for use in queries, telemetry, and relationship operations:

Invoice.p.status
Invoice.l.customer

TypeScript checks these names against the definition. See Objects for reading and writing instances, and Querying for filtering and following links.

Extend a type

Use extends when one type is a specialization of another. Pass the imported parent definition to inherit its properties, links, and TypeScript types:

// ontology/credit-note.ts
import { defineObjectType, prop } from "@sixb/core/ontology"
import { Invoice } from "./invoice"

export const CreditNote = defineObjectType({
  id: "CreditNote",
  name: "Credit note",
  extends: Invoice,
  properties: [prop("reason", "string", { required: true })],
})

CreditNote inherits the primary ID, invoice properties, and customer link, and adds reason. A child property or link with the same ID replaces the parent's definition. The parent must also be exported from ontology/ so Sixb can discover it.

To reuse a value such as an address across otherwise unrelated types, use a value type.