How can i build mongoose model from this JSON

Question

I'm a beginner trying to parse this json into a mongoose model so i can save the data.

This is my model right now

const commentSchema = new Schema([{

  sectionId: String,comments:
 [{

      id: String,
      authorAvatarUrl: String,
      authorName: String,
      authorId: String,
      authorUrl: String,
      comment: String,

replies:
 [{
        id: String,
        authorAvatarUrl: String,
        authorName: String,
        authorId: String,
        authorUrl: String,
        comment: String,
        parentId: String
      }]
  }]

}]);

const Comment = mongoose.model("Comment", commentSchema);
module.exports = Comment;

and this is the Json i'm trying to map

var existingComments = [{
    "sectionId": "1",
    "comments":
 [{
        "id": 88,
        "authorAvatarUrl": "support/images/jon_snow.png",
        "authorName": "Jon Sno",
        "authorId": 1,
        "authorUrl": "http://en.wikipedia.org/wiki/Kit_Harington",
        "comment": "I'm Ned Stark's bastard",
        "replies":
 [{
          "id": 100,
          "authorAvatarUrl": "support/images/jon_snow.png",
          "authorName": "Jon Sno",
          "authorId": 1,
          "authorUrl": "http://en.wikipedia.org/wiki/Kit_Harington",
          "comment": "P.S.: I know nothing.",
          "parentId": 88
        }]
    }]
}]

On the server side i'm trying to get the comment like this

//Comment posted
router.post("/comments", (req, res, next) => {
  //Save the comment on database
  const [{
    sectionId,

comments:
 [{
      id,
      authorAvatarUrl,
      authorName,
      authorId,
      authorUrl,
      comment,

      replies: 
[{
        id,
        authorAvatarUrl,
        authorName,
        authorId,
        authorUrl,
        comment,
        parentId
      }]
    }]
  }] = req.body;


  const newComment = new Comment([{
    sectionId,comments:
 [{ id, }]

 }]);

  newComment
    .save()
    .then(comment => {
      res.redirect("/index");

    })

    .catch(err => {
      console.log(err);
    });

});

But is not working, any help will be much appreciated because i'm currently trying to uinderstand moongose ODM better. Thanks!!!!

Answer 1

Your comment schema is a bit confusing. You created a "Comment" schema (note this is singular) yet you are trying to use the comment schema as an array of comments.

Tip: Keep your schemas and singular.

To achieve your desired design whilst keeping your models singular you can try this:

Solution (1): Have a single "Section" collection storing all the data Note: although you have multiple schemas, we only ever model the SectionSchema and it will be our only collection where every Section document contains all the info you need.

const sectionSchema = new Schema({
    name: {
        type: String,
        required: [true, 'Section name is required']
    },
    comments: {
        type: [commentSchema]
    }
});

const replySchema = new Schema({
    //id: String, //not needed, mongoose will automatically add an "_id" property when you save 
    authorAvatarUrl: String,
    authorName: String,
    authorId: String,
    authorUrl: String,
    comment: String,
    parentId: String
});

const commentSchema = new Schema({
    //id: String, //not needed, mongoose will automatically add an "_id" property when you save 
    authorAvatarUrl: String,
    authorName: String,
    authorId: String,
    authorUrl: String,
    comment: String,
    replies:{
        type: [replySchema]
    }
});

module.exports =  mongoose.model("Section", sectionSchema);

In the above solution, you can still have routes to address only specific comments, for example:

router.get("/sections/:id") //gets the entire section document matching the ID
router.post("/sections/:id/comments/") //creates a new comment within section with matching ID. Simply push a new comment into the comments array
router.get("/sections/:id/comments/") //gets all the comments for this section. Simply return only the comments property of the section document.
router.get("/sections/:id/comments/:commentId") //gets a specific comment within a specific section. Filter the comments array to get the comment matching the commentId and then only return that.

etc..

---

Final note: there are other ways you can model your data. This is just one example. For instance, you can have a section collection and a comment collection, where a comment document stores a section Id indicating the section that that comment document relates to.

Have a look at https://mongoosejs.com/docs/subdocs.html and https://docs.mongodb.com/manual/core/data-modeling-introduction/ it might help you to understand the different ways you can model your data and also how mongoose subdocuments work and how to use them.