自动递增序列 Mongoose

Question

I implemented a auto increment sequence field in mongoose. I set the default/starting value as 5000. But it does not start from 5000, it starts from 1.

Heres my code:

My Counter Schema

// app/models/caseStudyCounter.js
// load the things we need
var mongoose = require('mongoose');
var bcrypt   = require('bcrypt-nodejs');

// define the schema for our user model
var caseStudyCounterSchema = mongoose.Schema({
   _id: {type: String, required: true},
   seq: {type: Number, default: 5000}

});

// methods ======================

// create the model for users and expose it to our app
module.exports = mongoose.model('caseStudyCounter', caseStudyCounterSchema);

My Main Schema:

// grab the mongoose module
var caseStudyCounter = require('../models/caseStudyCounter');
var mongoose = require("mongoose");

// grab the bcrypt module to hash the user passwords
var bcrypt   = require('bcrypt-nodejs');

// define the schema for our model
var caseStudySchema = mongoose.Schema({
     caseStudyNo: Number,
     firstName: String,
     lastName: String,

 });

caseStudySchema.pre('save', function(next) {
  var doc = this;

caseStudyCounter.findByIdAndUpdate({_id: 'caId'},{$inc: { seq: 1}},{"upsert": true,"new": true  }, function(error, counter)   {
    if(error)
        return next(error);
    doc.caseStudyNo = counter.seq;
    next();
});

});
 // module.exports allows us to pass this to other files when it is called
 // create the model for users and expose it to our app
 module.exports = mongoose.model('CaseStudy', caseStudySchema);

I can't figure out why its starting form 1 when I have set the default as 5000. The sequence should be 5001, 5002, 5003 and so on. Any help will be greatly appreciated.

Answer 1

Probably this is why it happens: https://github.com/Automattic/mongoose/issues/3617#issuecomment-160296684

Use the setDefaultsOnInsert option. Or just manually use {$inc: {n:1}, $setOnInsert: {n:776} }

Answer 2

You can install mongoose-auto-increment .

yourSchema.plugin(autoIncrement.plugin, {
    model: 'model',
    field: 'field',
    startAt: 5000,
    incrementBy: 1
});

It's easy to install and use.

Answer 3

This is such a common need that it might be worthwhile using an existing module. I played around with a few, but this was the easiest to get to work with my project. https://www.npmjs.com/package/mongoose-sequence . Remember if you want to repurpose the _id field, you must declare it as a Number type in your schema as per the docs.

Answer 4

I was also facing same issue so i came up with this solution.

var mongoose = require("mongoose");

// define the schema for our model
var caseStudySchema = mongoose.Schema({
 caseStudyNo: {
  type:Number,
  default:5000
 },
 firstName: String,
 lastName: String,
});

caseStudySchema.pre('save', function(next) {

var doc = this;

//Retrieve last value of caseStudyNo
CaseStudy.findOne({},{},{sort: { 'caseStudyNo' :-1}}, function(error, counter)   {
//if documents are present in collection then it will increament caseStudyNo 
// else it will create a new documents with default values 

    if(counter){
      counter.caseStudyNo++;
      doc.caseStudyNo=counter.caseStudyNo;
    }
    next();
 });
});
// module.exports allows us to pass this to other files when it is called
// create the model for users and expose it to our app
const CaseStudy = mongoose.model('CaseStudy', caseStudySchema);
module.exports = CaseStudy;

Answer 5

You can use this module.

mongoose-easy-auto-increment

Wish it can help you.