How to add created at and updated at fields to mongoose schemas?

When defining a schema in Mongoose, the created_at and updated_at fields are commonly used to track when records are created and last updated. To add these fields in Mongoose, you can utilize the built-in timestamps option, which automatically includes them in your schema. Here is an example of how to implement it in a Mongoose schema:

javascript
const mongoose = require('mongoose');

const Schema = mongoose.Schema;

// Define schema
const exampleSchema = new Schema({
  // Other fields of the schema
  name: {
    type: String,
    required: true
  },
  description: {
    type: String
  }
  // You don't need to explicitly define the created_at and updated_at fields
}, {
  timestamps: true // This will automatically add created_at and updated_at fields
});

// Create model
const ExampleModel = mongoose.model('Example', exampleSchema);

module.exports = ExampleModel;

In this example, setting timestamps to true instructs Mongoose to automatically add created_at and updated_at fields to each schema instance. When you create a new document, Mongoose automatically sets the values of created_at and updated_at fields to the current timestamp. When you update a document, only the updated_at field is updated to the latest timestamp.

By default, these fields are named created_at and updated_at. If you want to customize these field names, you can pass an object containing createdAt and updatedAt properties:

javascript
const exampleSchema = new Schema({
  // Other fields of the schema
  name: {
    type: String,
    required: true
  },
  description: {
    type: String
  }
}, {
  timestamps: { createdAt: 'created_at', updatedAt: 'updated_at' } // Customize field names
});

Using the timestamps option ensures that these fields are automatically handled during document creation or update, allowing you to easily track the history of documents without adding extra code.