WP_REST_Revisions_Controller::get_items() WordPress Method

	public function get_items( $request ) {
		$parent = $this->get_parent( $request['parent'] );
		if ( is_wp_error( $parent ) ) {
			return $parent;
		}

		// Ensure a search string is set in case the orderby is set to 'relevance'.
		if ( ! empty( $request['orderby'] ) && 'relevance' === $request['orderby'] && empty( $request['search'] ) ) {
			return new WP_Error(
				'rest_no_search_term_defined',
				__( 'You need to define a search term to order by relevance.' ),
				array( 'status' => 400 )
			);
		}

		// Ensure an include parameter is set in case the orderby is set to 'include'.
		if ( ! empty( $request['orderby'] ) && 'include' === $request['orderby'] && empty( $request['include'] ) ) {
			return new WP_Error(
				'rest_orderby_include_missing_include',
				__( 'You need to define an include parameter to order by include.' ),
				array( 'status' => 400 )
			);
		}

		if ( wp_revisions_enabled( $parent ) ) {
			$registered = $this->get_collection_params();
			$args       = array(
				'post_parent'      => $parent->ID,
				'post_type'        => 'revision',
				'post_status'      => 'inherit',
				'posts_per_page'   => -1,
				'orderby'          => 'date ID',
				'order'            => 'DESC',
				'suppress_filters' => true,
			);

			$parameter_mappings = array(
				'exclude'  => 'post__not_in',
				'include'  => 'post__in',
				'offset'   => 'offset',
				'order'    => 'order',
				'orderby'  => 'orderby',
				'page'     => 'paged',
				'per_page' => 'posts_per_page',
				'search'   => 's',
			);

			foreach ( $parameter_mappings as $api_param => $wp_param ) {
				if ( isset( $registered[ $api_param ], $request[ $api_param ] ) ) {
					$args[ $wp_param ] = $request[ $api_param ];
				}
			}

			// For backward-compatibility, 'date' needs to resolve to 'date ID'.
			if ( isset( $args['orderby'] ) && 'date' === $args['orderby'] ) {
				$args['orderby'] = 'date ID';
			}

			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php */
			$args       = apply_filters( 'rest_revision_query', $args, $request );
			$query_args = $this->prepare_items_query( $args, $request );

			$revisions_query = new WP_Query();
			$revisions       = $revisions_query->query( $query_args );
			$offset          = isset( $query_args['offset'] ) ? (int) $query_args['offset'] : 0;
			$page            = (int) $query_args['paged'];
			$total_revisions = $revisions_query->found_posts;

			if ( $total_revisions < 1 ) {
				// Out-of-bounds, run the query again without LIMIT for total count.
				unset( $query_args['paged'], $query_args['offset'] );

				$count_query = new WP_Query();
				$count_query->query( $query_args );

				$total_revisions = $count_query->found_posts;
			}

			if ( $revisions_query->query_vars['posts_per_page'] > 0 ) {
				$max_pages = ceil( $total_revisions / (int) $revisions_query->query_vars['posts_per_page'] );
			} else {
				$max_pages = $total_revisions > 0 ? 1 : 0;
			}

			if ( $total_revisions > 0 ) {
				if ( $offset >= $total_revisions ) {
					return new WP_Error(
						'rest_revision_invalid_offset_number',
						__( 'The offset number requested is larger than or equal to the number of available revisions.' ),
						array( 'status' => 400 )
					);
				} elseif ( ! $offset && $page > $max_pages ) {
					return new WP_Error(
						'rest_revision_invalid_page_number',
						__( 'The page number requested is larger than the number of pages available.' ),
						array( 'status' => 400 )
					);
				}
			}
		} else {
			$revisions       = array();
			$total_revisions = 0;
			$max_pages       = 0;
			$page            = (int) $request['page'];
		}

		$response = array();

		foreach ( $revisions as $revision ) {
			$data       = $this->prepare_item_for_response( $revision, $request );
			$response[] = $this->prepare_response_for_collection( $data );
		}

		$response = rest_ensure_response( $response );

		$response->header( 'X-WP-Total', (int) $total_revisions );
		$response->header( 'X-WP-TotalPages', (int) $max_pages );

		$request_params = $request->get_query_params();
		$base           = add_query_arg( urlencode_deep( $request_params ), rest_url( sprintf( '%s/%s/%d/%s', $this->namespace, $this->parent_base, $request['parent'], $this->rest_base ) ) );

		if ( $page > 1 ) {
			$prev_page = $page - 1;

			if ( $prev_page > $max_pages ) {
				$prev_page = $max_pages;
			}

			$prev_link = add_query_arg( 'page', $prev_page, $base );
			$response->link_header( 'prev', $prev_link );
		}
		if ( $max_pages > $page ) {
			$next_page = $page + 1;
			$next_link = add_query_arg( 'page', $next_page, $base );

			$response->link_header( 'next', $next_link );
		}

		return $response;
	}