Aggregation Pipeline Operators in mongoose

Question

How to use MongoDB Aggregation Pipeline Operators using Mongoose in nodejs

I am trying to count datewise data using aggregate

                  Walkins.aggregate([
                        {
                            $match:{'subscriberId': subsc._id},
                        },{
                            $project:{'date':{ $convert: { input:'$created', to: "date"} },
                        } },{
                            $project:{ 'dates': { $dateToString : { format: "%Y-%m-%d", date: "$created" } }} ,
                        },{
                            $group:{
                                _id:{'date': '$created'} ,
                                walkinsCount :{$sum: 1 }
                            }
                        }

                    ]).then((walkins)=>{    });

But it is troughing "MongoError: Unrecognized expression '$convert'" Error

                  Walkins.aggregate([
                        {
                            $match:{'subscriberId': subsc._id},
                        },{
                            $project:{'date':{ $toDate:'$created'} },
                        } },{
                            $project:{ 'dates': { $dateToString : { format: "%Y-%m-%d", date: "$created" } }} ,
                        },{
                            $group:{
                                _id:{'date': '$created'} ,
                                walkinsCount :{$sum: 1 }
                            }
                        }

                    ]).then((walkins)=>{    });

Answer 1

$toDate is only available in version 4.0 and above. Here, you can see it's written New in version 4.0. which means you can't use it with a MongoDB installation of anything lower than version 4.0.

If you're using Ubuntu and installed MongoDB using apt install mongodb, it installs version 3.6.3.

Check out the official documentation on how to install and run the latest version here for your OS.