将JSON对象传递为模型作为有效负载

Question

Im having an issue on my rails app. i'm letting Users submit and filled out bracket once they'r done editing it. :

 <%= form_for Tournoi.new do |f| %>
  <button id="SaveButton" onclick="save()">Save</button>
<% end %>

Using XMLHttpRequest i send the json object to my db :

function save() {
    var data = {};
    var tojs = myDiagram.model.toJSON();
    data.payload = tojs;
    //var parsed_json = JSON.parse(data);
    var json = JSON.stringify(data);
    myDiagram.isModified = false;

    var request = new XMLHttpRequest();
    request.onload = callback;
    request.open("post", "http://localhost:3000/malesingle", true);
    request.setRequestHeader("Content-Type", "application/json");
    request.send(json)

my migration is set up in a way that it accepts json object as payload :

class CreateTournois < ActiveRecord::Migration[5.1]
  def change
    create_table :tournois do |t|
      t.json 'payload'
      t.timestamps
    end
  end
end

my tournois controller is where i think im having some difficulties :

def create
     @tournoi = Tournoi.new params[:payload]
        if @tournoi.save
      redirect_to root_url
        flash[:success] = "Your tournament bracket has been validated!"
        redirect_to @tournoi
      else
        redirect_to malesingle_url
      end
  end

Here is the problem every time i try to submit the bracket, the content of my json object stringify appeared on my terminal, the POST argument seem to go through, my payload parameters becomes the content of my json object but for some reason i get a Argument Error (When assigning attributes, you must pass a hash as an argument.) which makes my migration roll back.

I know the error comes from my controller but i cant seem to find where i went wrong or if there is something missing or in the wrong order.

Answer 1

Since your Rails endpoint expects form data, send your JSON like this:

var tojs = myDiagram.model.toJSON();
var json = JSON.stringify(tojs);

var formData = new FormData();
formData.append("payload", json);

var request = new XMLHttpRequest();
request.open("post", "http://localhost:3000/malesingle", true);
request.send(formData);

Then, assuming you're using Postgres which supports fields of type JSON, the "payload" param needs to be parsed into a hash and the field name needs to be specified:

Tournoi.new(payload: JSON.parse(params[:payload]))