multiple-types.md

layout	default
title	Multiple Types
parent	Features
nav_order	6

Multiple Types

YAML Schema supports specifying multiple types for a value using an array. This allows a value to be validated against any of the specified types.

Basic Multiple Types

You can specify multiple types by providing an array of type names:

# Schema
type:
  - string
  - number

Valid examples:

"I'm a string"

42

Invalid examples:

null

true

an:
  - arbitrarily
  - nested
data: structure

The value must be either a string OR a number.

Multiple Types with Constraints

When using multiple types, constraints are applied to each type where applicable:

# Schema
type:
  - string
  - number
minimum: 1
minLength: 1

Valid examples:

1

"one"

Invalid examples:

0

""

In this example:

• For numbers, the minimum: 1 constraint applies, so 0 is invalid
• For strings, the minLength: 1 constraint applies, so "" is invalid

Use Cases

Multiple types are useful when:

1. Accepting different representations: A value might be provided as either a string or a number
2. Backward compatibility: Supporting both old and new formats
3. Flexible schemas: Allowing users to choose the most convenient format

Comparison with anyOf

Multiple types (type: [string, number]) is similar to using anyOf:

# Using multiple types
type:
  - string
  - number

# Using anyOf
anyOf:
  - type: string
  - type: number

However, multiple types is more concise when you only need to specify types without additional constraints. Use anyOf when you need different constraints for each type or more complex composition.