CODEWITHSUNDEEP
phpjqueryjsonajaxpost
user3458861
user3458861

Reputation: 1301

jQuery Ajax error 200 parse error

I have read many articles related to my predicament but I do not understand my what my problem is so please someone help explain it to me:

I want to use jQuery ajax to post a value to a PHP file:

$().ready(function(){
"use strict";
$("#ansSubmit").click(function() {
    $.ajax({
        type: "POST",
        url: "updateScore.php",
        dataType: "json",
        data:{ 
            data : JSON.stringify(flag)
        },
        success: function(data) {
            alert(data.reply);
        },
        error: function(jqXHR, textStatus, errorThrown) {
          alert("jqXHR: " + jqXHR.status + "\ntextStatus: " + textStatus + "\nerrorThrown: " + errorThrown);
        }
    });  
    $("#infoDiv").load("updateScore.php"); // to see what $_POST contains
  });
});

The flag variable being sent is an integer.

Here is my updated updateScore.php (the PHP file I am posting to):

<?php
session_start();

$returned = array("reply" => "no data received");

if(isset($_POST["data"])) {
   $returned["reply"] = $_POST["data"];
}

print_r($_POST);

echo json_encode($returned);

?>

"no data received" is returned so at least I know it reached updateScore.php but now I need help establishing why it not sending anything through - I am 100% sure flag has a value.

Additional information:

  1. mime.types has all JSON options active.
  2. console.log(data) returns Uncaught Reference Error: data is not defined.
  3. errorThrown returns Parse error: unexpected < in position 0 - I can get this to say unexpected A in position 0 but it is still an empty array that is being sent.
  4. print_r($_POST) returns Array()

Upvotes: 1

Views: 3078

Answers (2)

Quentin
Quentin

Reputation: 943751

First you tell the server that you are sending it JSON:

contentType: "application/json",

Then you pass an object to data. This gets encoded as application/x-www-form-urlencoded (which is not JSON although it happens to have JSON embedded inside it).

data:{ 
    data : JSON.stringify(flag)
},

Then in the PHP you try to read from $_POST

if(isset($_POST["data"])) {

… but $_POST is empty because you told the server you were sending JSON so didn't try to decode it.

Remove this line:

contentType: "application/json",

… because it is a lie that breaks your code.

Alternatively

You could actually send JSON:

contentType: "application/json",
data: JSON.stringify(flag),

… and then read it from the raw request body instead of (the still unpopulated) $_POST.

$json = file_get_contents('php://input');
$data = json_decode($json);

Upvotes: 1

imvain2
imvain2

Reputation: 15847

From your examples, you are expecting a json object to be returned BUT you are echoing it works .....

try this sample code in php:

$returned = array("reply" => "not found");

if(isset($_POST["data"])) {
     $returned["reply"] = "It works!" . $_POST["data"];
}

echo json_encode($returned);

basically this sample code sets an array returned with reply by default as not found. If data is available, it sets reply to your message. Then after that it echoes a json version of the message.

Upvotes: 0

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