Auto increment a property value in Strongloop loopback model

Ok, This solution works but I am bypassing Loopback and the "mongoDB connector". Here is what I am doing.

Given a model named Sequence that looks like this:

{    "_id": {        "$oid": "54ab3ec0cc074e24144f26d7"    },    "collection": "SpecialOrder",    "value": 113}

I am doing this:

mongoConnector = app.dataSources.MyMongoDBConnectorName.connector;mongoConnector.collection("Sequence").findAndModify({collection: 'SpecialOrder'}, [['_id','asc']], {$inc: { value: 1 }}, {new: true}, function(err, sequence) {        if(err) {            console.log(err.message);        } else {            // Do what I need to do with new incremented value sequence.value        }    });

Seems like there should be a built in LoopbackJS way of doing this. A lot to go through just to increment a value.

Thanks,

Warren Bell

Have same problem, but with Postgres. Fixed just using altering column 'id' manually in database (set type to SERIAL which means auto-increment in Postgres). I think problem could be resolved in this way on any database.

I want to share my approach, which is similar to the author's answer, but with using Loopback's methods.Here is the Sequence model I've created:

{  "name": "sequence",  "base": "PersistedModel",  "idInjection": true,  "options": {    "validateUpsert": true  },  "properties": {    "name": {      "type": "string",      "required": true    },    "value": {      "type": "number",      "required": true    }  },  "validations": [],  "relations": {},  "acls": [],  "methods": []}

You can store as many sequences as you want in this model. Then I create a sequence I need with this script (in this case order sequence):

var app = require('./server/server');var Sequence = app.models.Sequence;Sequence.findOrCreate({  where: {    name: 'order'  }}, {  name: 'order',  value: 0}, function (err) {  if (err) {    console.log(err);  }  process.exit();});

Now everytime I need order number to create an order, first I update the order record in Sequence model by incrementing its value and then use it:

var Sequence = Order.app.models.Sequence;Sequence.findOne({  where: {    name: 'order'  }}).then(function (orderNumber) {  orderNumber.value++;  return orderNumber.save();}).then(function (orderNumber) {  Order.upsert({    orderNumber: orderNumber.value,    ...  });});

Cheers!