How to Properly Insert Decoded JSON to Mysql Database

Question

Iv been searching the internet on how to make my php code for my database works and i cant understand any of it! thats why i have no choice but to just ask a question i hope someone can help me or guide me on this matter. Any help is very much appreciated!

Question: I want to insert a JSON format data to mysql database.

String Request Code in Android

public void insertCartProducttoDatabase() {

    StringRequest stringRequest = new StringRequest(Request.Method.POST,
            Constants.cartdata_url,
            new com.android.volley.Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        JSONObject jsonObject = new JSONObject(response);
                        if (!jsonObject.getBoolean("error")) {
                            Toast.makeText(getApplicationContext(),
                                    jsonObject.getString("message"),
                                    Toast.LENGTH_LONG).show();
                            finish();
                        } else {
                            Toast.makeText(getApplicationContext(),
                                    jsonObject.getString("message"),
                                    Toast.LENGTH_LONG).show();
                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("response", "" + error);
        }
    }) {

        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<String, String>();

            params.put(KEY_VC_ARRAY, convertedArray);
            //params.put(KEY_VC_BRANCH, branchid);
            return params;
        }
    };
    RequestHandler.getInstance(this).addToRequestQueue(stringRequest);
}

logcat Result: This is the array result comming from my recycler view

[
{
    "productname": "Siopao",
    "quantity": "3",
    "totalprice": 1500
},
{
    "productname": "Siomai",
    "quantity": "3",
    "totalprice": 297
},
{
    "productname": "Burger",
    "quantity": "4",
    "totalprice": 200
}
]

PHP CODE DB Operations.php (UPDATEDv2)

//INSERT CART PRODUCTS 
    public function insertIndividualCart($cartarray){
        $receivedArray = $_POST['cartarray'];
        $new_array = json_decode($receivedArray,true);
        var_dump($new_array);

        $stmt = $this->con->prepare("INSERT INTO `cart_data` (`cartid`, `productname`, `quantity`, `totalprice`, `created`) 
        VALUES (NULL, ?, ?, ?, CURRENT_TIMESTAMP )");

        foreach($new_array as $row){ 

            $stmt->bind_param('ssi', $row['productname'], $row['quantity'], $row['totalprice']);

            if($stmt->execute()){
                return 1;
            }else{
                return 2;
            }
        }
    }

PHP CODE cartData.php

<?php
require_once '../DbOperations.php';
$response = array();
if($_SERVER['REQUEST_METHOD']=='POST'){
if(
    isset($_POST['cartarray']) 
){
    //operations data
    $db = new DbOperations();

    $result = $db->insertIndividualCart(
        $_POST['cartarray']
    );

    if($result == 1){
        $response['error'] = false;
        $response['message'] = "Success";
    }elseif($result == 2){
        $response['error'] = true;
        $response['message'] = "Failed, Error Occured";
    }

}else{
    $response['error'] = true;
    $response['message'] = "Required Field are missing";
}

}else{
$response['error'] = true;
$response['message'] = "Invalid Request";
}
 echo json_encode($response);

I know my php code Dboperation.php is wrong. its just i dont know how to start i saw a video, that i have to decode first my array comming from android and then use foreach and inside use Insert, What i cant understand is that how can i use bind params on the array that i just decoded? or do i need to? cause what i understand is in order for my code to work i need to use bind params depending on the paramter that i used on public function right? (idk what its called what i mean by public function is like this one " public function insertIndividualCart($cartarray){} " ) im just a beginner guys so go easy on me! i just dont have any choice but to just ask since i really cant understand the things that they did in their post.

Answer 1

This is not a full answer, but it should give you an idea where you have gone wrong. You need to execute the query inside a loop.

public function insertIndividualCart($cartarray)
{
    $new_array = json_decode($cartarray, true);
    $stmt = $this->con->prepare("INSERT INTO `cart_data` (`cartid`, `productname`, `quantity`, `totalprice`, `created`) 
        VALUES (NULL, ?, ?, ?, CURRENT_TIMESTAMP)");

    foreach ($new_array as $row) {
        // you have 3 placeholders in SQL, so you need 3 variables bound
        $stmt->bind_param('sss', $row['productname'], $row['quantity'], $row['totalprice']);
        $stmt->execute();
    }

    return true;
}

See how much shorter it is? Prepare the query before the loop and then bind values inside the loop and execute