public function get_item_schema() {
		$schema = array(
			'$schema'    => 'http://json-schema.org/draft-04/schema#',
			'title'      => 'bp_activity',
			'type'       => 'object',
			'properties' => array(
				'id'                => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'A unique numeric ID for the activity.', 'buddypress' ),
					'readonly'    => true,
					'type'        => 'integer',
				),
				'primary_item_id'   => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The ID of some other object primarily associated with this one.', 'buddypress' ),
					'type'        => 'integer',
				),
				'secondary_item_id' => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The ID of some other object also associated with this one.', 'buddypress' ),
					'type'        => 'integer',
				),
				'user_id'           => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The ID for the author of the activity.', 'buddypress' ),
					'type'        => 'integer',
				),
				'link'              => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The permalink to this activity on the site.', 'buddypress' ),
					'format'      => 'uri',
					'type'        => 'string',
				),
				'component'         => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The active BuddyPress component the activity relates to.', 'buddypress' ),
					'type'        => 'string',
					'enum'        => array_keys( buddypress()->active_components ),
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_key',
					),
				),
				'type'              => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The activity type of the activity.', 'buddypress' ),
					'type'        => 'string',
					'enum'        => array_keys( bp_activity_get_types() ),
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_key',
					),
				),
				'title'             => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'The description of the activity\'s type (eg: Username posted an update)', 'buddypress' ),
					'type'        => 'string',
					'readonly'    => true,
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
				),
				'content'           => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'Allowed HTML content for the activity.', 'buddypress' ),
					'type'        => 'object',
					'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 activity, as it exists in the database.', 'buddypress' ),
							'type'        => 'string',
							'context'     => array( 'edit' ),
						),
						'rendered' => array(
							'description' => __( 'HTML content for the activity, transformed for display.', 'buddypress' ),
							'type'        => 'string',
							'context'     => array( 'view', 'edit' ),
							'readonly'    => true,
						),
					),
				),
				'date'              => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( "The date the activity was published, in the site's timezone.", 'buddypress' ),
					'type'        => 'string',
					'format'      => 'date-time',
				),
				'status'            => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'Whether the activity has been marked as spam or not.', 'buddypress' ),
					'type'        => 'string',
					'enum'        => array( 'published', 'spam' ),
					'readonly'    => true,
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_key',
					),
				),
				'comments'          => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'A list of objects children of the activity object.', 'buddypress' ),
					'type'        => 'array',
					'readonly'    => true,
				),
				'comment_count'     => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'Total number of comments of the activity object.', 'buddypress' ),
					'type'        => 'integer',
					'readonly'    => true,
				),
				'hidden'            => array(
					'context'     => array( 'edit' ),
					'description' => __( 'Whether the activity object should be sitewide hidden or not.', 'buddypress' ),
					'type'        => 'boolean',
				),
				'favorited'         => array(
					'context'     => array( 'view', 'edit' ),
					'description' => __( 'Whether the activity object has been favorited by the current user.', 'buddypress' ),
					'type'        => 'boolean',
					'readonly'    => true,
				),
			),
		);

		// Avatars.
		if ( true === buddypress()->avatar->show_avatars ) {
			$avatar_properties = array();

			$avatar_properties['full'] = array(
				'context'     => array( 'view', 'edit' ),
				/* translators: Full image size for the member Avatar */
				'description' => sprintf( __( 'Avatar URL with full image size (%1$d x %2$d pixels).', 'buddypress' ), number_format_i18n( bp_core_avatar_full_width() ), number_format_i18n( bp_core_avatar_full_height() ) ),
				'type'        => 'string',
				'format'      => 'uri',
			);

			$avatar_properties['thumb'] = array(
				'context'     => array( 'view', 'edit' ),
				/* translators: Thumb imaze size for the member Avatar */
				'description' => sprintf( __( 'Avatar URL with thumb image size (%1$d x %2$d pixels).', 'buddypress' ), number_format_i18n( bp_core_avatar_thumb_width() ), number_format_i18n( bp_core_avatar_thumb_height() ) ),
				'type'        => 'string',
				'format'      => 'uri',
			);

			$schema['properties']['user_avatar'] = array(
				'context'     => array( 'view', 'edit' ),
				'description' => __( 'Avatar URLs for the author of the activity.', 'buddypress' ),
				'type'        => 'object',
				'readonly'    => true,
				'properties'  => $avatar_properties,
			);
		}

		/**
		 * Filters the activity schema.
		 *
		 * @param string $schema The endpoint schema.
		 */
		return apply_filters( 'bp_rest_activity_schema', $this->add_additional_fields_schema( $schema ) );
	}