Attachment credits

README.md

@@ -76,8 +76,9 @@ To set up a configuration file, add a `ups-editorial.php` file to your theme's r
  */
 
 return array(
-  'bylines'        => true,
-  'article_topper' => true,
+  'bylines'           => true,
+  'article_topper'    => true,
+  'attachment_credit' => true,
 );
 ```
 
@@ -99,6 +100,14 @@ Enable or disable the plugin's `Author` taxonomy, as well as the control mechani
 
 Enable or disable the registration of fields for article toppers and the Gutenberg panel that controls those fields.
 
+#### `attachment_credit`
+
+**Allowed types:** `boolean`
+
+**Default value:** `true`
+
+Enable or disable the registration of a `credit` field for attachments.
+
 ## Theme API
 
 There are a few globally-available functions that can be used by your theme to retrieve data defined by this plugin's functionality. These functions are defined in the `Template.php` file at the root of the plugin directory, and exist under the `Upstatement\Editorial` namespace.

UpsEditorial.php

@@ -29,8 +29,6 @@ class UpsEditorial {
 	 * @return void
 	 */
 	public static function register() {
-		$plugin = new self();
-
 		Config::read();
 		Assets::register();
 
@@ -41,6 +39,10 @@ public static function register() {
 		if ( Config::get( 'article_topper' ) ) {
 			Meta\ArticleTopper::register();
 		}
+
+		if ( Config::get( 'attachment_credit' ) ) {
+			Meta\AttachmentCredit::register();
+		}
 	}
 }
 

includes/Config.php

@@ -14,11 +14,14 @@ class Config {
 	 * @var array
 	 */
 	private static array $defaults = array(
-		// Enables the bylines functionality, including the `Authors` taxonomy.
-		'bylines'        => true,
+		// Enable the bylines functionality, including the `Authors` taxonomy.
+		'bylines'          => true,
 
 		// Enable the article topper fields.
-		'article_topper' => true,
+		'article_topper'   => true,
+
+		// Enable the credit field for attachments.
+		'attachment_credit' => true,
 	);
 
 	/**

includes/Meta/AttachmentCredit.php

@@ -0,0 +1,110 @@
+<?php
+/**
+ * Registers a meta field for attachment credits.
+ *
+ * @package Upstatement\Editorial
+ */
+
+namespace Upstatement\Editorial\Meta;
+
+use WP_Post;
+
+class AttachmentCredit {
+
+	/**
+	 * Fields to add to the attachment post type.
+	 *
+	 * @var array
+	 */
+	private $attachment_fields = array(
+		array(
+			'id' => 'credit',
+			'label' => 'Credit',
+			'input' => 'text',
+			'helps' => 'Provide credit to the creator',
+			'single' => true,
+		)
+	);
+
+	/**
+	 * Register the credit feature.
+	 *
+	 * @return void
+	 */
+	public static function register() {
+		$attachment_credit = new self();
+
+		add_filter( 'attachment_fields_to_edit', array( $attachment_credit, 'register_edit_fields' ), 10, 2 );
+		add_filter( 'attachment_fields_to_save', array( $attachment_credit, 'handle_save_fields'), 10, 2 );
+
+		add_action( 'rest_api_init', array( $attachment_credit, 'register_rest_fields' ) );
+	}
+
+	/**
+	 * Register the attachment fields for editing.
+	 *
+	 * @see https://developer.wordpress.org/reference/hooks/attachment_fields_to_edit/
+	 *
+	 * @param array   $fields Array of attachment form fields.
+	 * @param WP_Post $post   Attachment object.
+	 *
+	 * @return array
+	 */
+	public function register_edit_fields( $fields, $post ) {
+		foreach ( $this->attachment_fields as $field ) {
+			$fid            = $field['id'];
+			$value          = get_post_meta( $post->ID, $fid, true );
+			$fields[ $fid ] = array(
+				'show_in_rest' => true,
+				'label'        => $field['label'],
+				'input'        => $field['input'],
+				'value'        => $value,
+				'helps'        => $field['helps'],
+			);
+		}
+
+		return $fields;
+	}
+
+	/**
+	 * Handles saved attachment data.
+	 *
+	 * @param array $post       Array of post data.
+	 * @param array $attachment Attachment metadata.
+	 *
+	 * @return void
+	 */
+	public function handle_save_fields( $post, $attachment ) {
+		foreach ( $this->attachment_fields as $field ) {
+			$fid = $field['id'];
+			if ( isset( $attachment[ $fid ] ) ) {
+				update_post_meta( $post['ID'], $fid, sanitize_text_field( $attachment[ $fid ] ) );
+			} else {
+				delete_post_meta( $post['ID'], $fid );
+			}
+		}
+
+		return $post;
+	}
+
+	/**
+	 * Add the attachment fields for the Rest API.
+	 *
+	 * @return void
+	 */
+	public function register_rest_fields() {
+		foreach ($this->attachment_fields as $field) {
+			register_rest_field(
+				'attachment',
+				$field['id'],
+				array(
+					'get_callback'    => function($object) use ($field) {
+						return get_post_meta( $object['id'], $field['id'], $field['single'] );
+					},
+					'update_callback' => null,
+					'schema'          => null,
+				)
+			);
+		}
+	}
+}