Cache the number of replies in the post object. See #5050.

https://github.com/NodeBB/NodeBB/pull/5050#pullrequestreview-4248269

src/posts.js

@@ -260,21 +260,11 @@ var plugins = require('./plugins');
 		});
 	};
 
-	Posts.countReplies = function(pid, callback) {
+	Posts.getReplyPids = function (pid, callback) {
-		if (Array.isArray(pid)) {
-			db.sortedSetsCard(pid.map(function (id) {
-				return 'pid:' + id + ':replies';
-			}), callback);
-		} else {
-			db.sortedSetCard('pid:' + pid + ':replies', callback);
-		}
-	};
-
-	Posts.getReplyPids = function(pid, callback) {
 		db.getSortedSetRange('pid:' + pid + ':replies', 0, -1, callback);
 	};
 
-	Posts.getReplyPosts = function(pid, uid, callback) {
+	Posts.getReplyPosts = function (pid, uid, callback) {
 		async.waterfall([
 			function (next) {
 				Posts.getReplyPids(pid, next);

src/posts/create.js

@@ -86,7 +86,10 @@ module.exports = function (Posts) {
 						if (!postData.toPid) {
 							return next(null);
 						}
-						db.sortedSetAdd('pid:' + postData.toPid + ':replies', timestamp, postData.pid, next);
+						async.parallel([
+							async.apply(db.sortedSetAdd, 'pid:' + postData.toPid + ':replies', timestamp, postData.pid),
+							async.apply(db.incrObjectField, 'post:' + postData.toPid, 'replies')
+						], next);
 					},
 					function (next) {
 						db.incrObjectField('global', 'postCount', next);

src/posts/delete.js

@@ -137,7 +137,7 @@ module.exports = function (Posts) {
 					function (next) {
 						deletePostFromUsersVotes(pid, next);
 					},
-					function(next) {
+					function (next) {
 						Posts.getPostField(pid, 'toPid', function (err, toPid) {
 							if (err) {
 								return next(err);
@@ -145,7 +145,10 @@ module.exports = function (Posts) {
 							if (!parseInt(toPid, 10)) {
 								return next(null);
 							}
-							db.sortedSetRemove('pid:' + toPid + ':replies', pid, next);
+							async.parallel([
+								async.apply(db.sortedSetRemove, 'pid:' + toPid + ':replies', pid),
+								async.apply(db.decrObjectField, 'post:' + toPid, 'replies')
+							], next);
 						});
 					},
 					function (next) {

src/topics/posts.js

@@ -65,9 +65,6 @@ module.exports = function (Topics) {
 			voteData: function (next) {
 				posts.getVoteStatusByPostIDs(pids, uid, next);
 			},
-			replies: function (next) {
-				posts.countReplies(pids, next);
-			},
 			userData: function (next) {
 				var uids = [];
 
@@ -126,7 +123,7 @@ module.exports = function (Topics) {
 					postObj.upvoted = results.voteData.upvotes[i];
 					postObj.downvoted = results.voteData.downvotes[i];
 					postObj.votes = postObj.votes || 0;
-					postObj.replies = results.replies[i] || 0;
+					postObj.replies = postObj.replies || 0;
 					postObj.selfPost = !!parseInt(uid, 10) && parseInt(uid, 10) === parseInt(postObj.uid, 10);
 
 					// Username override for guests, if enabled

src/upgrade.js

@@ -908,7 +908,7 @@ Upgrade.upgrade = function (callback) {
 				next();
 			}
 		},
-		function(next) {
+		function (next) {
 			thisSchemaDate = Date.UTC(2016, 9, 14);
 
 			if (schemaDate < thisSchemaDate) {
@@ -917,20 +917,23 @@ Upgrade.upgrade = function (callback) {
 
 				var posts = require('./posts');
 				var batch = require('./batch');
-				batch.processSortedSet('posts:pid', function(ids, next) {
+				batch.processSortedSet('posts:pid', function (ids, next) {
-					posts.getPostsFields(ids, ['pid', 'toPid', 'timestamp'], function(err, data) {
+					posts.getPostsFields(ids, ['pid', 'toPid', 'timestamp'], function (err, data) {
 						if (err) {
 							return next(err);
 						}
 
-						async.each(data, function(postData, next) {
+						async.each(data, function (postData, next) {
 							if (!parseInt(post.toPid, 10)) {
 								return next(null);
 							}
-							db.sortedSetAdd('pid:' + postData.toPid + ':replies', postData.timestamp, postData.pid, next);
+							async.parallel([
+								async.apply(db.sortedSetAdd, 'pid:' + postData.toPid + ':replies', postData.timestamp, postData.pid),
+								async.apply(db.incrObjectField, 'post:' + postData.toPid, 'replies')
+							], next);
 						}, next);
 					});
-				}, function(err) {
+				}, function (err) {
 					if (err) {
 						return next(err);
 					}