feat: write API shorthand to query post routes by their topic index (requires tid in either query string or request body)

middleware.checkRequired is also updated to check for matches in req.query as well.

src/controllers/write/posts.js

@@ -1,11 +1,40 @@
 'use strict';
 
+const nconf = require('nconf');
+
+const db = require('../../database');
+const topics = require('../../topics');
 const posts = require('../../posts');
 const api = require('../../api');
 const helpers = require('../helpers');
 
 const Posts = module.exports;
 
+Posts.redirectByIndex = async (req, res, next) => {
+	const { tid } = req.query || req.body;
+
+	let { index } = req.params;
+	if (index < 0 || !isFinite(index)) {
+		index = 0;
+	}
+	index = parseInt(index, 10);
+
+	let pid;
+	if (index === 0) {
+		pid = await topics.getTopicField(tid, 'mainPid');
+	} else {
+		pid = await db.getSortedSetRange(`tid:${tid}:posts`, index - 1, index - 1);
+	}
+	pid = Array.isArray(pid) ? pid[0] : pid;
+	if (!pid) {
+		return next('route');
+	}
+
+	const path = req.path.split('/').slice(3).join('/');
+	const urlObj = new URL(nconf.get('url') + req.url);
+	res.redirect(308, nconf.get('relative_path') + encodeURI(`/api/v3/posts/${pid}/${path}${urlObj.search}`));
+};
+
 Posts.get = async (req, res) => {
 	const post = await api.posts.get(req, { pid: req.params.pid });
 	if (!post) {

src/middleware/index.js

@@ -270,7 +270,7 @@ middleware.validateAuth = helpers.try(async (req, res, next) => {
 
 middleware.checkRequired = function (fields, req, res, next) {
 	// Used in API calls to ensure that necessary parameters/data values are present
-	const missing = fields.filter(field => !req.body.hasOwnProperty(field));
+	const missing = fields.filter(field => !req.body.hasOwnProperty(field) && !req.query.hasOwnProperty(field));
 
 	if (!missing.length) {
 		return next();

src/routes/write/posts.js

@@ -34,5 +34,8 @@ module.exports = function () {
 	setupApiRoute(router, 'put', '/:pid/diffs/:since', middlewares, controllers.write.posts.restoreDiff);
 	setupApiRoute(router, 'delete', '/:pid/diffs/:timestamp', middlewares, controllers.write.posts.deleteDiff);
 
+	// Shorthand route to access post routes by topic index
+	router.all('/+byIndex/:index*?', [middleware.checkRequired.bind(null, ['tid'])], controllers.write.posts.redirectByIndex);
+
 	return router;
 };