Conditionally Update/Insert and Add To Array

Question

I have .tsv file with some orders information. After remake into my script i got this.

[{"order":"5974842dfb458819244adbf7","name":"Сергей Климов","email":"[email protected]"},
{"order":"5974842dfb458819244adbf8","name":"Сушков А.В.","email":"[email protected]"},
{"order":"5974842dfb458819244adbf9","name":"Виталий","email":"[email protected]"},
...
and so on

I have a scheema into mongoose.

var ClientSchema = mongoose.Schema({
  name:{
    type: String
  },
  email:{
    type: String,
    unique : true,
    required: true,
    index: true
  },
  forums:{
    type: String
  },
  other:{
    type: String
  },
  status:{
    type: Number,
    default: 3
  },
  subscribed:{
    type: Boolean,
    default: true
  },
  clienturl:{
    type: String  
  },
  orders:{
    type: [String]
  }
});

clienturl is an password 8 chars length, that generated by function.

module.exports.arrayClientSave = function(clientsArray,callback){
  let newClientsArray = clientsArray
    .map(function(x) {
      var randomstring = Math.random().toString(36).slice(-8);
      x.clienturl = randomstring;
      return x;
    });
  console.log(newClientsArray);
  Client.update( ??? , callback );
}

But i dont undestand how to make an update. Just if email already exsists push orders array, but not rewrite all other fields. But if email not exsists - save new user with clienturl and so on. Thanks!

I didnt comment just cuz started learning about bulkWrite and mongo usage. Answer was like i need. — Mikita Melnikau
– Mikita Melnikau, Commented Jul 27, 2017 at 11:48

Neil Lunn · Accepted Answer · 2017-07-24 04:11:11Z

Probably the best way to handle this is via .bulkWrite() which is a MongoDB method for sending "multiple operations" in a "single" request with a "single" response. This counters the need to control async functions in issue and response for each "looped" item.

module.exports.arrayClientSave = function(clientsArray,callback){
  let newClientsArray = clientsArray
    .map(x => {
      var randomstring = Math.random().toString(36).slice(-8);
      x.clienturl = randomstring;
      return x;
    });
    console.log(newClientsArray);

    let ops = newClientsArray.map( x => (
      { "updateOne": {
        "filter": { "email": x.email },
        "update": {
          "$addToSet": { "orders": x.order },
          "$setOnInsert": {
            "name": x.name,
            "clientUrl": x.clienturl
          }
        },
        "upsert": true
      }}
    ));

    Client.bulkWrite(ops,callback);
};

The main idea there being that you use the "upsert" functionality of MongoDB to drive the "creation or update" functionality. Where the $addToSet only appends the "orders" property information to the array where not already present, and the $setOnInsert actually only takes effect when the action is actually an "upsert" and not applied when the action matches an existing document.

Also by applying this within .bulkWrite() this becomes a "single async call" when talking to a MongoDB server that supports it, and that being any version greater than or equal to MongoDB 2.6.

However the main point of the specific .bulkWrite() API, is that the API itself will "detect" if the server connected to actually supports "Bulk" operations. When it does not, this "downgrades" to individual "async" calls instead of one batch. But this is controlled by the "driver", and it will still interact with your code as if it were actually one request and response.

This means all the difficulty of dealing with the "async loop" is actually handled in the driver software itself. Being either negated by the supported method, or "emulated" in a way that makes it simple for your code to just use.

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