So i've began to create a comment section for users to leave comments under posted events. I'm now trying to set up replies to comments under an event and am having issues. With the code I have, a new link is being generated but it isn't updating the dataset. Can anyone spot what I've done wrong? @app.route("/api/v1.0/posts/<string:id>/discussions/<string:discussion_id>/reply", methods = ["POST"]) def add_new_reply(id, comment_id): new_reply = { "_id" : ObjectId(), "username" : request.form["username"], "comment" : request.form["comment"] } post.update_one( { "_id" : ObjectId(comment_id) }, { "$push": { "reply" : new_reply } } ) new_reply_link = "http://localhost:5000/api/v1.0/posts/" + id + \ "/comments/" + comment_id + "/reply/" + str(new_reply['_id']) return make_response( jsonify( { "url" : new_reply_link } ), 201 ) The structure of the post dataset is as follows: Post comment (array) object reply (array) object Continue reading...