public function get_item_schema() {
		if ( $this->schema ) {
			return $this->add_additional_fields_schema( $this->schema );
		}

		$schema = array(
			'$schema'    => 'http://json-schema.org/draft-04/schema#',
			'title'      => $this->post_type,
			'type'       => 'object',
			// Base properties for every Post.
			'properties' => array(
				'date'         => array(
					'description' => __( "The date the object was published, in the site's timezone." ),
					'type'        => array( 'string', 'null' ),
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit', 'embed' ),
				),
				'date_gmt'     => array(
					'description' => __( 'The date the object was published, as GMT.' ),
					'type'        => array( 'string', 'null' ),
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
				),
				'guid'         => array(
					'description' => __( 'The globally unique identifier for the object.' ),
					'type'        => 'object',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
					'properties'  => array(
						'raw'      => array(
							'description' => __( 'GUID for the object, as it exists in the database.' ),
							'type'        => 'string',
							'context'     => array( 'edit' ),
							'readonly'    => true,
						),
						'rendered' => array(
							'description' => __( 'GUID for the object, transformed for display.' ),
							'type'        => 'string',
							'context'     => array( 'view', 'edit' ),
							'readonly'    => true,
						),
					),
				),
				'id'           => array(
					'description' => __( 'Unique identifier for the object.' ),
					'type'        => 'integer',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'link'         => array(
					'description' => __( 'URL to the object.' ),
					'type'        => 'string',
					'format'      => 'uri',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'modified'     => array(
					'description' => __( "The date the object was last modified, in the site's timezone." ),
					'type'        => 'string',
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'modified_gmt' => array(
					'description' => __( 'The date the object was last modified, as GMT.' ),
					'type'        => 'string',
					'format'      => 'date-time',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'slug'         => array(
					'description' => __( 'An alphanumeric identifier for the object unique to its type.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'edit', 'embed' ),
					'arg_options' => array(
						'sanitize_callback' => array( $this, 'sanitize_slug' ),
					),
				),
				'status'       => array(
					'description' => __( 'A named status for the object.' ),
					'type'        => 'string',
					'enum'        => array_keys( get_post_stati( array( 'internal' => false ) ) ),
					'context'     => array( 'view', 'edit' ),
				),
				'type'         => array(
					'description' => __( 'Type of Post for the object.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'edit', 'embed' ),
					'readonly'    => true,
				),
				'password'     => array(
					'description' => __( 'A password to protect access to the content and excerpt.' ),
					'type'        => 'string',
					'context'     => array( 'edit' ),
				),
			),
		);

		$post_type_obj = get_post_type_object( $this->post_type );
		if ( is_post_type_viewable( $post_type_obj ) && $post_type_obj->public ) {
			$schema['properties']['permalink_template'] = array(
				'description' => __( 'Permalink template for the object.' ),
				'type'        => 'string',
				'context'     => array( 'edit' ),
				'readonly'    => true,
			);

			$schema['properties']['generated_slug'] = array(
				'description' => __( 'Slug automatically generated from the object title.' ),
				'type'        => 'string',
				'context'     => array( 'edit' ),
				'readonly'    => true,
			);
		}

		if ( $post_type_obj->hierarchical ) {
			$schema['properties']['parent'] = array(
				'description' => __( 'The ID for the parent of the object.' ),
				'type'        => 'integer',
				'context'     => array( 'view', 'edit' ),
			);
		}

		$post_type_attributes = array(
			'title',
			'editor',
			'author',
			'excerpt',
			'thumbnail',
			'comments',
			'revisions',
			'page-attributes',
			'post-formats',
			'custom-fields',
		);
		$fixed_schemas        = array(
			'post'       => array(
				'title',
				'editor',
				'author',
				'excerpt',
				'thumbnail',
				'comments',
				'revisions',
				'post-formats',
				'custom-fields',
			),
			'page'       => array(
				'title',
				'editor',
				'author',
				'excerpt',
				'thumbnail',
				'comments',
				'revisions',
				'page-attributes',
				'custom-fields',
			),
			'attachment' => array(
				'title',
				'author',
				'comments',
				'revisions',
				'custom-fields',
			),
		);
		foreach ( $post_type_attributes as $attribute ) {
			if ( isset( $fixed_schemas[ $this->post_type ] ) && ! in_array( $attribute, $fixed_schemas[ $this->post_type ], true ) ) {
				continue;
			} elseif ( ! isset( $fixed_schemas[ $this->post_type ] ) && ! post_type_supports( $this->post_type, $attribute ) ) {
				continue;
			}

			switch ( $attribute ) {

				case 'title':
					$schema['properties']['title'] = array(
						'description' => __( 'The title for the object.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit', 'embed' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database()
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database()
						),
						'properties'  => array(
							'raw'      => array(
								'description' => __( 'Title for the object, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered' => array(
								'description' => __( 'HTML title for the object, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'editor':
					$schema['properties']['content'] = array(
						'description' => __( 'The content for the object.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database()
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database()
						),
						'properties'  => array(
							'raw'           => array(
								'description' => __( 'Content for the object, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered'      => array(
								'description' => __( 'HTML content for the object, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit' ),
								'readonly'    => true,
							),
							'block_version' => array(
								'description' => __( 'Version of the content block format used by the object.' ),
								'type'        => 'integer',
								'context'     => array( 'edit' ),
								'readonly'    => true,
							),
							'protected'     => array(
								'description' => __( 'Whether the content is protected with a password.' ),
								'type'        => 'boolean',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'author':
					$schema['properties']['author'] = array(
						'description' => __( 'The ID for the author of the object.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit', 'embed' ),
					);
					break;

				case 'excerpt':
					$schema['properties']['excerpt'] = array(
						'description' => __( 'The excerpt for the object.' ),
						'type'        => 'object',
						'context'     => array( 'view', 'edit', 'embed' ),
						'arg_options' => array(
							'sanitize_callback' => null, // Note: sanitization implemented in self::prepare_item_for_database()
							'validate_callback' => null, // Note: validation implemented in self::prepare_item_for_database()
						),
						'properties'  => array(
							'raw'       => array(
								'description' => __( 'Excerpt for the object, as it exists in the database.' ),
								'type'        => 'string',
								'context'     => array( 'edit' ),
							),
							'rendered'  => array(
								'description' => __( 'HTML excerpt for the object, transformed for display.' ),
								'type'        => 'string',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
							'protected' => array(
								'description' => __( 'Whether the excerpt is protected with a password.' ),
								'type'        => 'boolean',
								'context'     => array( 'view', 'edit', 'embed' ),
								'readonly'    => true,
							),
						),
					);
					break;

				case 'thumbnail':
					$schema['properties']['featured_media'] = array(
						'description' => __( 'The ID of the featured media for the object.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit', 'embed' ),
					);
					break;

				case 'comments':
					$schema['properties']['comment_status'] = array(
						'description' => __( 'Whether or not comments are open on the object.' ),
						'type'        => 'string',
						'enum'        => array( 'open', 'closed' ),
						'context'     => array( 'view', 'edit' ),
					);
					$schema['properties']['ping_status']    = array(
						'description' => __( 'Whether or not the object can be pinged.' ),
						'type'        => 'string',
						'enum'        => array( 'open', 'closed' ),
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'page-attributes':
					$schema['properties']['menu_order'] = array(
						'description' => __( 'The order of the object in relation to other object of its type.' ),
						'type'        => 'integer',
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'post-formats':
					// Get the native post formats and remove the array keys.
					$formats = array_values( get_post_format_slugs() );

					$schema['properties']['format'] = array(
						'description' => __( 'The format for the object.' ),
						'type'        => 'string',
						'enum'        => $formats,
						'context'     => array( 'view', 'edit' ),
					);
					break;

				case 'custom-fields':
					$schema['properties']['meta'] = $this->meta->get_field_schema();
					break;

			}
		}

		if ( 'post' === $this->post_type ) {
			$schema['properties']['sticky'] = array(
				'description' => __( 'Whether or not the object should be treated as sticky.' ),
				'type'        => 'boolean',
				'context'     => array( 'view', 'edit' ),
			);
		}

		$schema['properties']['template'] = array(
			'description' => __( 'The theme file to use to display the object.' ),
			'type'        => 'string',
			'context'     => array( 'view', 'edit' ),
			'arg_options' => array(
				'validate_callback' => array( $this, 'check_template' ),
			),
		);

		$taxonomies = wp_list_filter( get_object_taxonomies( $this->post_type, 'objects' ), array( 'show_in_rest' => true ) );
		foreach ( $taxonomies as $taxonomy ) {
			$base                          = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
			$schema['properties'][ $base ] = array(
				/* translators: %s: Taxonomy name. */
				'description' => sprintf( __( 'The terms assigned to the object in the %s taxonomy.' ), $taxonomy->name ),
				'type'        => 'array',
				'items'       => array(
					'type' => 'integer',
				),
				'context'     => array( 'view', 'edit' ),
			);
		}

		$schema_links = $this->get_schema_links();

		if ( $schema_links ) {
			$schema['links'] = $schema_links;
		}

		$this->schema = $schema;
		return $this->add_additional_fields_schema( $this->schema );
	}