Error while inserting javascript array to mongodb using mongoose

Question

I am quite new to node and mongodb. I was trying to insert a javascript array variable to mongodb using mongoose. But it result in an error.

I am getting an error message when I run this code :

ValidationError: CastError: Cast to Array failed for value "[object Object],[object Object],[object Object]" at path "questions"

This is my schema I have defined

var mongoose = require('mongoose');
var questionSchema = new mongoose.Schema({
    questionSet : String,
    // questionTime:Number,
    questions:[{
        //questionID : String,
        questionNo : String,
        questionSection : String,
        questionStatement : String,
        answerA : String,
        answerB : String,
        answerC : String,
        answerD : String,
        correctAnswer : String
    }]
});
module.exports = mongoose.model('Question', questionSchema);

To insert data into mongodb using mongoose, I use this code.

var Question = require('../schemas/questions');
exports.testing = function(req,res){
    if (!req.body) return res.sendStatus(400)

    var ques_set = req.body.set;
    var question_array = req.body.ques;
var data = Question({question_set: ques_set, questions: question_array});

    data.save(function(err) {
        if (err) throw err;
        else {
            console.log('Question Inserted');
            res.send("Question Inserted");    
        }
    });
  };

I am using this javascript to create a question array similar to my schema. Here I use push() method to create a question array.

function myFunction1(){
        document.getElementById("questionSet").disabled = true;

        var questionSet = document.getElementById("form_manu").elements[0].value;
    }

function myFunction3(){
    if(count < totalQuestion) {
        question.push({
            questionID:document.getElementById("form").elements[4].value,
            questionSection:document.getElementById("form").elements[5].value,
            questionStatement:document.getElementById("form").elements[6].value,
            answerA : document.getElementById("form").elements[7].value,
            answerB : document.getElementById("form").elements[8].value,
            answerC : document.getElementById("form").elements[9].value,
            answerD : document.getElementById("form").elements[10].value,
            correctAnswer : document.getElementById("form").elements[11].value
        });

UPDATE1
To send the javascript variables, I use the following javascript function post

    function post(path, params, method) {
    method = method || "post"; // Set method to post by default if not specified.

    // The rest of this code assumes you are not using a library.
    // It can be made less wordy if you use one.
    var form = document.createElement("form");
    form.setAttribute("method", method);
    form.setAttribute("action", path);

    for(var key in params) {
        if(params.hasOwnProperty(key)) {
            var hiddenField = document.createElement("input");
            hiddenField.setAttribute("type", "hidden");
            hiddenField.setAttribute("name", key);
            hiddenField.setAttribute("value", params[key]);

            form.appendChild(hiddenField);
         }
    }

    document.body.appendChild(form);
    form.submit();
}

I call this javascript function from the html body using <button onclick="post('question', {set: questionSet, ques : question })">Send</button>

I have printed the variables ques_set and question_array on console. ques_set prints out the string I am passing in, but question_array just shows [object Object],[object Object] .

UPDATE 2
When I use JSON.stringify() on variable questions, its shows like

[{"questionNo":"1","questionSection":"sec1","questionStatement":"ques1","answerA":"string1","answerB":"string2","answerC":"string3","answerD":"string4","correctAnswer":"A"},{"questionNo":"2","questionSection":"sec2","questionStatement":"Ques2","answerA":"string1","answerB":"string2","answerC":"string3","answerD":"string4","correctAnswer":"B"}]

I know this description is much lengthy,But I can't reduce it. My apologies.

Answer 1

I am not sure if your example of JSON.stringify(question_array) is being run on the browser or on the server. So I'll go out on a limb here.

You are posting as:

<button onclick="post('question', {set: questionSet, ques : question })">Send</button>

My guess is that you are not getting an error on set because questionSet is really a string -- But question is not being stringified before/during transmission (server is really receiving a string [object Object],[object Object] that is generated on the browser, or there is some kind of dataType issue on the client or server.

You could try this first:

<button onclick="post('question', {set: questionSet, ques : JSON.stringify(question) })">Send</button>

UPDATE :

In fact, your form generation code is doing this:

hiddenField.setAttribute("value", params[key]);

so, at some point params["ques"] contains an array of objects, not a string. JS will print [object Object] for each of the {} objects contained inside the question array. You can do this:

hiddenField.setAttribute("value", JSON.stringify(params[key]));

Answer 2

Change your questionSchema variable definition to:

var questionVariable = new mongoose.Schema({
    //questionID : String,
    questionNo : String,
    questionSection : String,
    questionStatement : String,
    answerA : String,
    answerB : String,
    answerC : String,
    answerD : String,
    correctAnswer : String
});

var questionSchema = new mongoose.Schema({
    questionSet : String,
    // questionTime:Number,
    questions:[questionVariable]
});

This is required since mongoose is not able to parse the object without a related schema. Now when you create a new Schema for the internal question object and refer it in the main questionSchema mongoose should be able to parse your object.