Creating multiple comments on a blog post

Project repo https://github.com/zootechdrum/scrapeWithMongo

Hello again,
I am having trouble storing multiple comments on blog posts in my MongoDB collection. There is no authentication so anyone on the site can feel free to comment whatever they like. What I am trying to do is add comments to one blog post. As of now I have only been successful in updating the one comment associated with the blog post. However, I can’t seem to save multiple comments into one collection.

I am using mongoose.
//comment schema

var mongoose = require("mongoose");

// Save a reference to the Schema constructor
var Schema = mongoose.Schema;

// Using the Schema constructor, create a new CommentSchema object
// This is similar to a Sequelize model
var CommentSchema = new Schema({
  // `body` is of type String
  body: String
});

// This creates our model from the above schema, using mongoose's model method
var Comment = mongoose.model("comment", CommentSchema);

// Export the Note model
module.exports = Comment;
var mongoose = require("mongoose");

// Save a reference to the Schema constructor
var Schema = mongoose.Schema;

// Using the Schema constructor, create a new UserSchema object
// This is similar to a Sequelize model
var ArticleSchema = new Schema({

  image: {
    type: String,
    required: true
  },

  // `title` is required and of type String
  title: {
    type: String,
    required: true
  },
  // `link` is required and of type String
  link: {
    type: String,
    required: true
  },
  description: {
    type: String,
    required: true
  },
  // `comment` is an object that stores a Note id
  // The ref property links the ObjectId to the Comment model
  // This allows us to populate the Article with an associated Comment
  comment: {
    type: Schema.Types.ObjectId,
    ref: "comment"
}
  
});

// This creates our model from the above schema, using mongoose's model method
var Article = mongoose.model("Article", ArticleSchema);

// Export the Article model
module.exports = Article;

Below is the route where I would like to save more comments. Its not working though.

app.post("/articles/:id", function(req, res) {
    console.log(req.body)
    // Create a new note and pass the req.body to the entry
    db.Comment.create(req.body)
      .then(function(dbComment) {
    //       console.log(dbComment)
    //     // If a Note was created successfully, find one Article with an `_id` equal to `req.params.id`. Update the Article to be associated with the new Note
    //     // { new: true } tells the query that we want it to return the updated User -- it returns the original by default
    //     // Since our mongoose query returns a promise, we can chain another `.then` which receives the result of the query
        return db.Article.update({ _id: req.params.id }, { $push: {comment: dbComment._id }})
})
      .then(function(dbArticle) {
        // If we were able to successfully update an Article, send it back to the client
        res.json(dbArticle);
      })
      .catch(function(err) {
        // If an error occurred, send it to the client
        res.json(err);
      });
  });

}

I get an error message in the console and it states

errmsg: "The field 'comment' must be an array but is of type objectId in document {_id: ObjectId('5e3d6c7804277cb4144213b8')}"