如何定义mongodb模式以及如何将post方法写入以下调查屏幕

我试图添加具有多个答案的多个问题，但无法将其存储在MongoDB中，我希望将每个问题存储为单个对象。

const mongoose = require("mongoose"); 
const Schema = mongoose.Schema; 
const questionSchema = new mongoose.Schema({ questionType: { type: Schema.Types.ObjectId, ref:"questionType", required: true }, questionTitle: { type: String, required: true }, questions:{ type: Array, required: true }, question: { type: String, required: true }, answer: { type: Array, required: true }, createdBy: { type: String, required: true }, }, module.exports = mongoose.model("question", questionSchema);

Associated screenshot

var async = require("async");

exports.createQuestions = (req,res) => {
   let ress=[];
   async.each(req.body,function(item,callback)
   { 
    const questions = new Questions(item);
    Questions.find({questionTitle:item.questionTitle},function(err,data){
           if(err){
               console.log(err);
           }
          else if(data.length>0){
               ress.push( {
                   'message':item.questionTitle+'is already existed'
                });
                callback();
            }
           else if(data.length==0){
            questions.save().then(result => {
            ress.push({
           "message": "added successfully",
           "status":200,
           "data":result})
           console.log('result',ress)
           callback();
            });
        }
    })   
   },
   function(err) {
    console.log('iterating done',err);
    return res.json({"result":ress});
})
};