AJAX not posting or receiving apparently - php

Question

I tell you what, getting AJAX to work is one pain in the wazoo! It took me ages to get a simple string to pass and then I got a json array working and felt good, now I've tried to make a little adjustment and broke the whole thing again. Why is following giving an ajax error and how can I get under the hood to see what's going on?
jQuery:
$('#upload_form option[value="addnew"]').click(function(){
// Show modal window
$('#add-new').modal('show');
// Get the class
var Classofentry = $(this).attr("class");
//console.log(Classofentry);
$('#add-new-submit').on('click', function(){
// Get new option from text field
var value = $('#add-new-text').val();
console.log(value);
$.ajax({
type: "POST",
url: "<?php echo site_url(); ?>main/change_options",
data: {new_option: value, new_option_class: Classofentry},
//dataType: "html",
dataType: "json",
error: errorHandler,
success: success
});
function success(data)
{
if (data[1]) // Only add new entry if unique
{
// Add new entry
//$('#animal_species').append("<option value='" + data + "'selected=\"selected\">" + data + "</option>");
$('#'+Classofentry).append("<option value='" + data[0] + "'selected=\"selected\">" + data[0] + "</option>");
//alert(data[0]);
}
else
{
// Select the nonunique value by emptying it and appending
$('#'+Classofentry).empty("<option value=''selected=\"selected\">" + data[0] + "</option>").append("<option value='" + data[0] + "'selected=\"selected\">" + data[0] + "</option>");
//alert(data[1]);
}
alert(data[1]);
//alert('Success!');
}
function errorHandler()
{
//alert('Error with AJAX!');
alert(data[0]);
}
$('#add-new-submit').unbind('click'); // This fixes the problem for multiple entries
$('#add-new').modal('toggle');
});
});
php:
public function change_options()
{
# Receives and sends back user-entered new option and adds it to database
# Get strings from ajax in view
$value = $_POST['new_option'];
$value_class = $_POST['new_option_class'];
#Make array to send to model
$value_array = array('Options' => $value);
$unique = true;
echo json_encode(array($value, $unique));
}
In the console I get: ReferenceError: data is not defined. I've spent the last couple days working on logic to determine $unique and now the ajax won't work, even when I strip it back to it's bare bones. What going on here?

Answer 1

Th code I posted should've worked. I found the issue and it wasn;t with ajax, it was with me passing the wrong thing to the model. Here's the working code, with the logic to determine $unique:
(BTW, this solves the problem posed in Form Validation in Codeigniter: using set_rules to check text input from a modal window without using Form Validation):
public function change_options()
{
# Receives and sends back user-entered new option and adds it to database
# Get strings from ajax in view
$value = $_POST['new_option'];
$value_class = $_POST['new_option_class'];
//print_r($value_class); die;
#Make array to send to model
$value_array = array('Options' => $value);
$unique = true;
$this->load->model('data_model');
$elements = $this->data_model->get_options($value_class);
foreach ($elements as $element)
{
if (preg_match("/$element/", $value, $matches))
{
$unique = false;
break;
}
}
# Add new option to dropdown in database
if ($unique) {$this->data_model->add_option($value_class, $value_array);}
//echo $value;
echo json_encode(array($value, $unique));
}