Build a custom REST endpoint which greets a name

Description: Create the endpoint GET /wp-json/tc/v1/greet?name=Riya, which returns {"greeting":"Hello, Riya!"}. If the name has more than 20 characters, the endpoint must return an error with the status 400.

Hint:

• Use register_rest_route() with a validate_callback for the name argument.
• A route needs a permission_callback.

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Solution

<?php
add_action( 'rest_api_init', function () {
	register_rest_route( 'tc/v1', '/greet', array(
		'methods'             => 'GET',
		'permission_callback' => '__return_true',
		'args'                => array(
			'name' => array(
				'required'          => true,
				'validate_callback' => function ( $value ) {
					return is_string( $value ) && strlen( $value ) <= 20;
				},
				'sanitize_callback' => 'sanitize_text_field',
			),
		),
		'callback'            => function ( WP_REST_Request $request ) {
			return array( 'greeting' => 'Hello, ' . $request['name'] . '!' );
		},
	) );
} );

How it works

• The route is on the rest_api_init hook. WordPress checks the arguments before the callback runs.
• A failed validate_callback gives rest_invalid_param with the status 400, and a missing required argument gives an error too.

Read Custom REST Endpoint.

• Previous Exercise

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