How to add new property to mongoDb model?

As Sharrzard Gh said, MongoDB doesn't allow you to add a new property to your model after it's been defined. Instead, use a structure like this, to define an initially empty property that you will use later to store the trend data.

const CoinSchema = new Schema({  specName: { type: String, required: true },  fullName: { type: String, required: true },  category:{ type: String, required: true },  coinName: { type: String, required: true },  trend: { type: String, required: true, default: '' }  // <- Add this property});module.exports = mongoose.model("coins", CoinSchema);

You can change the trend data type to an array or object if you need to store more complex data or a series of data points for historical trend tracking, if you want.

Try something like this:

trend: { type: Object, required: true, default: {} }

or

trend: { type: [String] , required: true, default: [] }

I was able to add new properties in the model even after the creation of the model in Node.js using:

insertMany(table_data, { strict: false });

where table_data container the old data appended with the new properties. The strict: false did the magic.

Order Model in Node:

const mongoose = require ('mongoose');const OrdersSchema = new mongoose.Schema({  sr_no :{type: Number, required:true},  customer_name :{type: String, required:true},  product_name: String,  codes: String,  code_date:{    type:Date,    default: Date.now()  },  design : String,  design_date :{    type:Date,    default: Date.now()  },  design_approval :{    type:String,    default: ''  },  design_approval_date :{    type:Date,    default: Date.now()  },  send_to_printer :{    type:String,    default: ''  },  send_to_printer_date :{    type:Date,    default: Date.now()  },  proof_approval :{    type:String,    default: ''  },  proof_approval_date :{    type:Date,    default: Date.now()  },  shipping : String,  ship_date :{    type:Date,    default: Date.now()  },  received :{    type:String,    default: ''  },  received_date :{    type:Date,    default: Date.now()  },  completed : String,  notes : String,  printing :{    type:String,    default: ''  },  printing_date :{    type:Date,    default: Date.now()  },  stapling :{    type:String,    default: ''  },  stapling_date :{    type:Date,    default: Date.now()  },  user_id :{type: Number, required:true}},{strict: false});OrdersSchema.index({ sr_no: -1 });const Orders = mongoose.model(  'Orders',  OrdersSchema);module.exports = Orders;

In Mongo Compass the first record appeared like:

And another record in the same collection was: