mongo aggregate/group/sum/avg

Author: firecodergithub

mongoAggregate.js

@@ -0,0 +1,19 @@
+var mongo=require('mongodb').MongoClient;
+mongo.connect('mongodb://localhost:27017/learnyoumongo',function (er,db) {
+		if (er) console.log('Eroare:'+er);
+		var col=db.collection('prices');
+		//console.log(process.argv[2]);
+		//col.find().toArray(function (err,dat){ console.log(dat)});//display all records
+		col.aggregate(
+			[{$match: {size:process.argv[2]}},
+			{$group : {
+					  _id:'total',
+					total: {$avg : '$price'}
+				  }
+			}]).toArray(function(err,results)
+				{
+					if (err) throw err;
+					console.log(Number(results[0].total).toFixed(2));
+					db.close();
+				});
+		});