This is responsible for handling our database interactions with registered users of our application. It will contain the following fields:

• fullName: This is a string value. The full name of the registered user. This is a required field, and should not be empty.
• email: This is also a string value. It is the email address of the registered user. Note that this value should be unique. We will make use of the mongoose-unique-validator plugin here to ensure the value is unique across all our app's users. This is a required field, and should not be empty.
• password: This is a hash of the user password. This should also be a string value. This is a required field, and should also not be empty.
• createdAt: The date the document was created. This can be saved as a JavaScript date object. The default value is the current date.
• updatedAt: The date the document was most recently updated. This can be saved as a JavaScript Date object. The default value is the current date.

To create the data model, let us create a User.js file in the ./models folder, and insert the following code into it:

const mongoose = require('mongoose');
const uniqueValidator = require('mongoose-unique-validator');

const schema = new mongoose.Schema({
 fullName: {
  type: String,
  required: true
 },
 email: {
  unique: true,
  type: String,
  required: true
 },
 password: {
  type: String,
  required: true
 },
 createdAt: { type: Date, default: Date.now },
 updatedAt: { type: Date, default: Date.now }
});

schema.plugin(uniqueValidator);
module.exports = mongoose.model('User', schema);

The mongoose-unique-validator plugin is used to add pre-save validation for unique fields within a Mongoose schema. After defining our schema, we export the model to be used in other places in our application.