Auto increment sequence in Mongoose - node.js

Question

I am trying to implement Auto increment in uisng mongoose.
But I am stuck.
Counter Schema
counter.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var counterSchema = new Schema({
_id: {type: String, required: true},
sequence_value: {type: Number, default: 1}
});
var Counter = module.exports = mongoose.model('Counter', counterSchema);
Product Schema
products.js
var productsSchema = new Schema({
productId: {type: String, require: false},
merchantId: {type: String, required: false}
)}
I have created counter collection and inserted one record inside it.
{
"_id" : "productId",
"sequence_value" : 1
}
Include method to increment the counter in the counter collection
//COUNTER COLLECTION
function getNextSequenceValue(sequenceName){
var sequenceDocument = Counters.findOneAndUpdate({
query:{_id: sequenceName },
update: {$inc:{sequence_value:1}},
new:true
});
return sequenceDocument.sequence_value;
}
Calling method to increment sequence number:
product.productId = getNextSequenceValue("productid");
But it's not working, nothing is getting saved in the products collection?

Answer 1

the next sequence should be
product.productId = getNextSequenceValue("productId"); // camelCase
in the counter collection you have added document with key productId (camelCase) but trying to get sequence with key productid (all lowercase)
mongo CLI
> function getNextSequenceValue(sequenceName){
...
... var sequenceDocument = db.counters.findOneAndUpdate(
... { "_id" : sequenceName },
... { $inc : { sequence_value : 1 } },
... { new : true }
... );
... return sequenceDocument.sequence_value;
... }
>
EDIT-2 with mongoose
var counterSchema = mongoose.Schema(
{
_id: { type: String, required: true },
sequence_value: { type: Number, default: 1 }
}
);
var Counters = mongoose.model('Counters', counterSchema);
var productsSchema = mongoose.Schema({
productId: {type: String, require: true},
merchantId: {type: String, required: false}
});
productsSchema.pre('save', function(next){
var doc = this;
Counters.findOneAndUpdate(
{ _id: 'productId' },
{ $inc : { sequence_value : 1 } },
{ new : true },
function(err, seq){
if(err) return next(err);
doc.productId = seq.sequence_value;
next();
}
);
}
);
var Product = mongoose.model('Product', productsSchema);
var testProduct = new Product({merchantId : 'test'})
testProduct.save(function (err, doc){
console.log('saved ' + doc )
})
output (with generated productId)
saravana#ubuntu:~/node-mongoose$ node app.js
`open()` is deprecated in mongoose >= 4.11.0, use `openUri()` instead, or set the `useMongoClient` option if using `connect()` or `createConnection()`. See http://mongoosejs.com/docs/connections.html#use-mongo-client
Mongoose: counters.findAndModify({ _id: 'productId' }, [], { '$inc': { sequence_value: 1 } }, { new: true, upsert: false, remove: false, fields: {} })
Mongoose: products.insert({ productId: '36', merchantId: 'test', _id: ObjectId("5a5b27b860716d24007df611"), __v: 0 })
saved { __v: 0,
productId: '36',
merchantId: 'test',
_id: 5a5b27b860716d24007df611 }
^C
saravana#ubuntu:~/node-mongoose$