ajax receives response from php but can not use with ajax - php

Question

I have the following php and ajax code when I check in google chrome with ctrl+shift+I in network tab it shows the response as <{"response" : "2"} but this response can't be assigned to <h3> having id as respo
my php is
<<?php
$id = $_POST['reccount'];
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
$link = mysqli_connect("localhost", "root", "", "testsite");
// Check connection
if($link === false){
die("ERROR: Could not connect. " . mysqli_connect_error());
}
// Attempt update query execution
$sql = "SELECT * FROM paper WHERE ID=$id";
if(mysqli_query($link, $sql)){
$result = mysqli_query($link, $sql);
while($row = mysqli_fetch_array($result)) {
$data['response']= $row['response'];
$data['ansnum'] = $row['q_no'];
}
echo json_encode($data);
} else {
echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
}
// Close connection
mysqli_close($link);
?>
and ajax is
$.ajax({
type:"POST",
url:"<?php echo base_url();?>/shortfiles/loadans.php",
data: {reccount: reccount},
dataType:"JSON",
success: function(data){
alert (data.response);
$('#respond').text(data.response);
}
}) ;
and html is
<h3 ID="respond"style="margin-left:30px;">response</h3>

Answer 1

If the response from your PHP is:
<{"response" : "2"}
This would be an incorrectly formatted JSON string. This would be created by the extra < you have at the beginning of the document. I would advise you have the following PHP Opener:
<?php
This should correct the issue so the JSON Response would be:
{"response" : "2"}
It will be properly parse at that point.
Example
<?php
$id = (int)$_POST['reccount'];
$link = mysqli_connect("localhost", "root", "", "testsite");
header('Content-Type: application/json');
if($link === false){
die("{\"error\": \"Could not connect. " . mysqli_connect_error() . "\"}");
}
$sql = "SELECT * FROM paper WHERE ID=$id";
if(mysqli_query($link, $sql)){
$result = mysqli_query($link, $sql);
while($row = mysqli_fetch_array($result)) {
$data['response']= $row['response'];
$data['ansnum'] = $row['q_no'];
}
echo json_encode($data);
} else {
echo "{\"error\": \"Unable to execute $sql. " . mysqli_error($link) . "\"}";
}
mysqli_close($link);
?>
In my example, I cast the POST data to Integer to help ensure a malicious user does not get to send anything other than a digit. I also only send JSON data, even when sending an error. Using the header() helps define the data for the browser.
$.ajax({
type:"POST",
url:"<?php echo base_url();?>/shortfiles/loadans.php",
data: {reccount: reccount},
dataType:"JSON",
success: function(data){
console.log(data);
if(data.error !== undefined){
alert(data.error);
} else {
$('#respond').text(data.response);
}
}
});
Hope that helps.