通过单独count和distinct的方式获取帖子列表的参与人数

app/service/forumThreadService.js

@@ -784,32 +784,43 @@ function getSubThreads(doc, sort, callback) {
     if (sort) {
         sortBy = sort;
     }
-    ForumThread.find(conditions, subThreadFields).populate('from', 'icon').limit(Number(20)).sort(sortBy).exec(function(err, docs) {
-        if (err) {
-            console.error(err);
-            callback(err, null);
-        } else {
-            var list = [];   //用户去重
-            _.forEach(docs, function(one, i) {
-                var flag = true;
-                _.forEach(list, function(two, k) {
-                    if(one.from._id == two.from._id){
-                        flag = false;
+    async.parallel([function(cb){
+       ForumThread.distinct('from', conditions, cb);
+    },function(cb){
+       countAllByFid(conditions, cb);
+    },function(cb){
+        ForumThread.find(conditions, subThreadFields).populate('from', 'icon').limit(Number(20)).sort(sortBy).exec(function(err, docs) {
+            if (err) {
+                console.error(err);
+                cb(err, null);
+            } else {
+                var list = [];   //用户去重
+                _.forEach(docs, function(one, i) {
+                    var flag = true;
+                    _.forEach(list, function(two, k) {
+                        if(one.from._id == two.from._id){
+                            flag = false;
+                        }
+                    });
+                    if(flag){
+                        list.push(one);
                     }
                 });
-                if(flag){
-                    list.push(one);
-                }
-            });
-            var obj = {};
-            obj.docTotal = docs.length;
-            obj.total = list.length;
-            obj.items = list;
-
-            var newDoc = doc.toObject();
-            newDoc.subThreads = obj;
-
-            callback(null, newDoc);
+                var obj = {};
+                obj.items = list;
+                var newDoc = doc.toObject();
+                newDoc.subThreads = obj;
+                cb(null, newDoc);
+            }
+        });
+    }],function(err, results){
+        if (err) {
+            callback(err);
+        } else {
+            var lastResult = results[2];
+            lastResult.subThreads.docTotal = result[1] || 0;
+            lastResult.subThreads.total = result[0];
+            callback(null, lastResult);
         }
     });
 }