mongoose

const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost:27017/collection_name', {});

mongoose.Promise = require('bluebird');

// messages.model.js

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const MessageSchema = new Schema({
    date: {
        type: Date,
        default: Date.now
    },
    content: {
        type: String
    },
    username: {
        type: String
    }
}, {
    versionKey: false,
    collection: 'MessageCollection'
});

MessageSchema.pre('save', function(next){
    if (this.isModified('date') || this.isNew()){
        this.date = new Date();
    }
    next();
});

module.exports = mongoose.model('MessageModel', MessageSchema);