आपका मॉड्यूल निर्यात गलत है
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var listSchema = new Schema({
name: { type: String, default: datestring + " List" }
});
**mongoose.exports = mongoose.model('List', listSchema);** <!-- this is wrong -->
यह होना चाहिए
**module.exports = mongoose.model('List', listSchema)**