Lecture 324:- Nested Population - Display Comment and Related User

To display comments and the user who posted them, we can use nested population in Mongoose. Nested population allows us to populate documents within documents.

Here's an example of how we can use nested population to display comments and their related user:

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Post.findById(postId)  .populate({    path: 'comments',    populate: {      path: 'user',      model: 'User'    }  })  .exec(function(err, post) {    if (err) return handleError(err);    console.log(post);  });

In this example, postId is the ID of the post we want to retrieve from the database. We use Mongoose's findById method to retrieve the post document.

Then we use the populate method to populate the comments array on the post document. We pass an object to populate with two properties:

• path: This is the name of the field we want to populate, in this case comments.
• populate: This is an object that specifies how to populate the user field on each comment. We set the path property to user, and the model property to User. This tells Mongoose to retrieve the User document associated with each comment's user field.

By using nested population, we can retrieve all the information we need to display a post's comments and their related user in a single query to the database.