extend

Type: object

Signature: object.extend(shape)

What It Is

This method page uses object.extend(shape) to enforce document-level structure checks, explicit section targeting, and typed field extraction over markdown content in extend use cases. In practice, 1 h1 heading and 1 h2 section is validated and emitted as top-level keys title and data using object(), string(), min(), and extend() under extend rules. When constraints are broken, issue codes like invalid_type identify exactly which extend node failed and why.

When to Use

Apply object.extend(shape) when your document flow requires composing reusable object contracts across related markdown schemas for extend and strict schema adherence over permissive parsing. It is less suitable for one-off payloads where object composition adds no reuse value under extend, because teams must accept key-level strictness that improves typing but rejects ad-hoc variations. Use object(), string(), min(), and extend() around object.extend(shape) to keep extend contracts transparent and reduce ambiguity in validation behavior.

object.extend(shape)

Input Markdown

# RUNBOOK: Object Extend

## 0. META

- service: fraud-api
- owner: risk-platform
- region: us-east-1

Schema

import { md } from '@markschema/mdshape'

const base = md.object({
  service: md.string().min(3),
  owner: md.string().min(3),
})

const extended = base.extend({
  region: md.string().min(3),
})

const schema = md.document({
  title: md.heading(1),
  data: md
    .section('0. META')
    .fields({
      service: md.string().min(3),
      owner: md.string().min(3),
      region: md.string().min(3),
    })
    .pipeline(extended),
})

Result

Success

{
  "success": true,
  "data": {
    "title": "RUNBOOK: Object Extend",
    "data": {
      "service": "fraud-api",
      "owner": "risk-platform",
      "region": "us-east-1"
    }
  }
}

Error

Failure trigger: remove region from 0. META; the field added by extend() is required and parsing fails.

{
  "success": false,
  "error": {
    "issues": [
      {
        "code": "missing_heading",
        "message": "Missing heading with depth 1",
        "path": [
          "title"
        ],
        "line": 1,
        "position": {
          "start": {
            "line": 1,
            "column": 1
          }
        }
      }
    ]
  }
}