property

$property

Extracts a named property value from an object. This operator is useful for accessing nested properties or extracting specific fields during processing pipelines.

Returns undefined if the current value is not an object or if the property doesn't exist. Throws a SchemaError if the specified property name is not defined in the schema.

Parameters

• name (string, required): The name of the schema-defined property to extract from the input object. The property must be declared in the current schema; use $get for arbitrary path access without schema awareness.

Example

// Conditionally require 'apiKey' only when 'useApiKey' is true
new Schema('object', {
  useApiKey: new Schema('boolean'),
  apiKey: new Schema('string').validator({
    $if: [{$property: 'useApiKey'}, '$non-empty']
  }),
})

// Discriminate a union using a schema property value
new Schema('object', {
  type: new Schema('string'),
  config: new Schema('any'),
}).discriminator({$property: 'type'})