在ajax POST方法期间，JSON对象作为NULL接收到服务器

Question

Searched around and couldn't seem to find an answer. I am using ajax to post this stringified array filled with objects, which JSONLint's alright to a php script which right now just returns it.

However over the transmission the object turns into NULL. Is there something wrong with the way I'm sending my string of JSON? I would really appreciate some advice for this, will give out virtual high fives. Thanks for your time!

JS

  var newDist = $("#distanceEl").val();
    var newDate = $("#dateEl").val();
    var newId = this.arr.length + 1;
    var newStat = new Stat(newId, newDist, newDate);

    this.arr.push(newStat);
    var newData = JSON.stringify(this.arr);
    console.log(newData);

    $.ajax({
        url : "php/post.php",
        type: "POST",
        dataType : "json",
        contentType : "application/json",
        data: newData,

        success: function(response)
        {
            console.log("Ajax: " + JSON.parse(response));
        },

        error: function(requestObject, error, errorThrown)
        {
            console.log("Error with Ajax Post Request:" + error);
            console.log(errorThrown);
        }
    });

PHP

 $jsonData = json_decode($_POST['newData']);
echo json_encode($jsonData);

Answer 1

Since you are using contentType : "application/json" on your request, the data you sent will not populate the $_POST. You can use file_get_contents('php://input')

You dont also need JSON.parse the response since you already using dataType : "json"

On your js

$.ajax({
    url : "php/post.php",
    type: "POST",
    dataType : "json",
    contentType : "application/json",
    data: newData,
    success: function(response)
    {
        console.log("Ajax: " , response);
    },
    error: function(requestObject, error, errorThrown)
    {
        console.log("Error with Ajax Post Request:" + error);
        console.log(errorThrown);
    }
});

On your PHP:

$input = file_get_contents('php://input');
$jsonData = json_decode($input);
echo json_encode($jsonData);

---

Other option is, don't sent your data as contentType : "application/json"

On your js:

var newData = [{"id":1,"distance":"1.2mi","date":"1/2/18"},{"id":1,"distance":"2.3mi","date":"1/4/18"},{"id":3,"distance":"1.7mi","date":"1/6/18"},{"id":4,"distance":"defaultDis","date":"defaultDate"}];

$.ajax({
    url : "data.php",
    type: "POST",
    dataType : "json",
    data: {newData : newData}, //Pass your data as object. No need to stringtify newData
    success: function(response)
    {
        console.log("Ajax: " , response);
    },
    error: function(requestObject, error, errorThrown)
    {
        console.log("Error with Ajax Post Request:" + error);
        console.log(errorThrown);
    }
});

On your PHP:

echo json_encode($_POST['newData']);