Ajax Post failing with a server response code 500 (Class 'CI_Controller' not found)

[eluser]stuartr[/eluser]
I have a table of schools, and an action button for each row of the table.

One of the actions generates a modal form to allow additional data to be entered for the relevant school, with the following code

Code:

<!-- Add Invoice -->
<li>&lt;?php echo anchor('admin/add_invoice/'.$row['school_id'], lang('add_invoice'), array( 'id' => 'id_add_invoice_' . $row['school_id'], 'class' => 'setup bold clsAddInvoice', 'data-school_id' => $row['school_id']));?&gt;</li>

Code:

$(".clsAddInvoice").click(function(){
  var schoolid = $(this).attr('data-school_id');
  $("#dialog-form").find("#school_id").val(schoolid);
  $( "#dialog-form" ).dialog( "open" );
  return false;
});

This then triggers the modal form

Code:

<div id="dialog-form" title="Enter Invoice Details"  auto;">
  <p class="validateTips">All form fields are required.</p>
<p><span id="form_mesg"></span></p>
&lt;?php
$attributes = array('class' => 'invoice', 'id' => 'add_invoice');
echo form_open('admin/add_invoice', $attributes);
echo "Enter Invoice Details Below<br />";
echo form_label('School ID:  ', 'school_id');
echo form_input('school_id', '', 'id="school_id"');
echo br(2);
echo form_label('Inv Ref:  ', 'inv_ref');
echo form_input('inv_ref', '', 'id="inv_ref"');
echo br(2);
echo form_label('Inv Date: ', 'inv_date');
echo form_input('inv_date', '', 'id="inv_date"');
echo br(2);
echo "Subscription Details<br />";
echo form_label('From:     ', 'inv_period_start');
echo form_input('inv_period_start', '', 'id="inv_period_start"');
echo br(2);
echo form_label('To:      ', 'inv_period_end');
echo form_input('inv_period_end', '', 'id="inv_period_end"');  

?&gt;
    <p><span id="alert_mesg"></span></p>
</div>

which after validation posts the data via ajax (currently hard-coded the data for testing purposes)

Code:

$.ajax({
     type: 'POST',
     url:  url,
     //data: data,
     data: { school_id: "13",
       inv_ref: "XYZABC",
       inv_date: "2012/12/31",
       inv_period_start: "2012/12/31",
       inv_period_end: "2012/12/31"
      
     },
     cache: false,
     success: function (msg) {
       alert( "Ajax Success: " + msg );
     },
     error: function (msg) {
       alert( "Ajax Failure: " + msg );
     }
    
    });

I can see from firebug the post command, but the server is responding with a 500 error.

Post Summary from Firebug

Code:

POST http://test.local/admin/add_invoice 500 Internal Server Error

Code:

school_id=13&inv_ref=XYZABC&inv_date=2012%2F12%2F31&inv_period_start=2012%2F12%2F31&inv_period_end=2012%2F12%2F31

The server nginx error log shows the following error:

Code:

[error] 20977#0 *23 FastCGI sent in stderr: "PHP message: PHP Fatal error: Class 'CI_Controller' not found in /home/www-data/website/system/core/CodeIgniter.php on line 231" while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: localhost, request: "GET /admin/add_invoice?school_id=13&inv_ref=XYZABC&inv_date=2012%2F12%2F31&inv_period_start=2012%2F12%2F31&inv_period_end=2012%2F12%2F31 HTTP/1.1, upstream: "fastcgi://127.0.0.1:9000, host "test.local"

The controller that is being called has largely been stripped on its functionality while I was trying to diagnose the issue, and isn't making any call on the model at the moment.

Code:

function add_invoice()
{
  if(!$this->tank_auth->is_admin_logged_in()) {
   redirect('admin/admin_login');
  } else {

   //stripped out content
   redirect('admin/invoices');

  }
  
  if($this->config->item('show_profiler'))
            $this->output->enable_profiler(TRUE, get_defined_vars());
    
}

[eluser]stuartr[/eluser]
Problem solved.

I wasn't including the language identifier within the URL