How to convert objectid to string in mongoose?

In Mongoose, each document in a model has an _id property that defaults to an ObjectId type. ObjectId is a built-in data type in MongoDB, typically used to uniquely identify documents.

There are several methods to convert ObjectId to a string:

1. Using the toString() method: Each ObjectId object includes a toString() method that converts it to a 24-bit hexadecimal string.

   javascript
   const idAsString = myDocument._id.toString();

2. Using the String constructor: You can directly convert ObjectId to a string using the String constructor.

   javascript
   const idAsString = String(myDocument._id);

3. Using ES6 template literals: ES6 template literals allow embedding ObjectId directly into a string, automatically invoking the toString() method.

   javascript
   const idAsString = `${myDocument._id}`;

4. Converting during queries: To obtain the string representation of _id during queries, define a virtual string field using Mongoose's virtual property feature.

   javascript
   schema.virtual('id').get(function(){
     return this._id.toHexString();
   });
   
   // Access the string form of _id
   const idAsString = myDocument.id;

These methods are applicable in various scenarios. For instance, when building an API that requires returning _id in JSON responses, since ObjectId is not a standard JSON type, conversion to string is often necessary. Using virtual properties in Mongoose enables automatic conversion when serializing documents to JSON.