Enumerated values

The enum keyword is used to restrict a value to a fixed set of values. It must be an array with at least one element, where each element is unique.

The following is an example for validating street light colors:

schema

{ "enum": ["red", "amber", "green"]}

data

"red"

compliant to schema

data

"blue"

not compliant to schema

You can use enum even without a type, to accept values of different types. Let's extend the example to use null to indicate "off", and also add 42, just for fun.

schema

{ "enum": ["red", "amber", "green", null, 42]}

data

"red"

compliant to schema

data

null

compliant to schema

data

42

compliant to schema

data

0

not compliant to schema