Basics

This page covers the fundamental concepts of YAML Schema, including empty schemas, boolean schemas, and basic type validation.

Empty Schema

An empty schema accepts any valid YAML value:

# Schema

Valid examples:

42

"I'm a string"

an:
  - arbitrarily
  - nested
data: structure

Boolean Schemas

true Schema

A schema with the value true accepts any value:

# Schema
true

Valid examples:

42

"I'm a string"

an:
  - arbitrarily
  - nested
data: structure

false Schema

A schema with the value false rejects all values:

# Schema
false

Invalid examples:

42

"I'm a string"

an:
  - arbitrarily
  - nested
data: structure

Type Validation

Supported Types

YAML Schema supports the following types:

• string
• number
• integer
• boolean
• null
• object
• array

Invalid Type Error

If you specify an unsupported type, validation will fail:

# Schema
type: foo

Error: Unsupported type: Expected type: string, number, integer, boolean, null, object, or array, but got: foo

String Type

# Schema
type: string

Valid examples:

""

"I'm a string"

Invalid examples:

42

an:
  - arbitrarily
  - nested
data: structure

Number Type

# Schema
type: number

Valid examples:

42

3.14

Invalid examples:

"I'm a string"

an:
  - arbitrarily
  - nested
data: structure

Object Type with Properties

# Schema
type: object
properties:
  foo:
    type: string
  bar:
    type: number

Valid examples:

foo: "I'm a string"
bar: 42

foo: "I'm a string"

Invalid examples:

foo: 42
bar: "I'm a string"

Error: [1:6] .foo: Expected a string, but got: Value(Integer(42))

Note: Missing properties are allowed by default unless required properties are specified.