Abilities API: Normalize input from schema

[gziolo]

Trac ticket: https://core.trac.wordpress.org/ticket/64139

Bug fix extracted from WordPress/abilities-api#108.

The problem

Without this patch REST would require a weird empty ?input field given how the current controller works with input schema that defines specific shape, example:

'input_schema'        => array(
	'type'                 => 'object',
 	'properties'           => array(
		'fields' => array(
			'type'        => 'array',
			'items'       => array(
				'type' => 'string',
				'enum' => $fields,
			),
			'description' => __( 'Optional: Limit response to specific fields. If omitted, all fields are returned.' ),
		),
	),
	'additionalProperties' => false,
	'default'              => array(),
),

Working examples:

GET /run?input # All fields
GET /run?input[fields][]=name # Filtered

We want the REST API controller to infer default value from the input schema, so it's possible to call:

GET /run # All fields

Solution

Normalizes the input for the ability, applying the default value from the input schema when needed.

When no input is provided and the input schema is defined with a top-level default key, this method returns the value of that key. If the input schema does not define a default, or if the input schema is empty, this method returns null. If input is provided, it is returned as-is.

---

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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Props gziolo.

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[github-actions]

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[jorgefilipecosta]

The code change looks and is properly tested 👍

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61047
GitHub commit: 409d03b

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.