我无法更新数据库中的数据：Codeigniter

Question

我无法更新数据库中的数据。我不知道发生了什么事。请帮助我。显示数据按编辑按钮。但我无法更新数据库中的数据。

Controller.php这样

public function ajax_update(){
$data = array(
    'festivalname' => $this->input->post('festivalname'),
    'description' => $this->input->post('description'),
    'dos' => $this->input->post('dos'),
    'doe' => $this->input->post('doe'),
    'place_id' => $this->input->post('place_id'),
    'pro_id' => $this->input->post('pro_id'),           
    );

    if($this->input->post('remove_fesimg')) // if remove photo checked
    {
        if(file_exists('upload/festivals/'.$this->input->post('remove_fesimg')) && $this->input->post('remove_fesimg'))
            unlink('upload/festivals/'.$this->input->post('remove_fesimg'));
        $data['fesimg'] = '';
    }

    if(!empty($_FILES['fesimg']['name']))
    {
        $upload = $this->_do_upload();

        //delete file
        $festival = $this->festivalmodel->get_by_id($this->input->post('fesid'));
        if(file_exists('upload/festivals'.$festival->fesimg) && $festival->fesimg)
            unlink('upload/festivals'.$festival->fesimg);

        $data['fesimg'] = $upload;
    }

    $this->festivalmodel->update(array('fesid' => $this->input->post('fesid')), $data);
    echo json_encode(array("status" => TRUE));
}

Model.php

public function update($where, $data)
{
  $this->db->update('tblfestival', $data, $where);
  return $this->db->affected_rows();
}   

的Javascript

function save(){

if(save_method == 'add') {
    url = "<?php echo site_url('index.php/festival/ajax_add')?>";
} else {
    url = "<?php echo site_url('index.php/festival/ajax_update')?>";
}

// ajax adding data to database
var formData = new FormData($('#form')[0]);/**/
$.ajax({
    url : url,
    type: "POST",
    data: formData,
    contentType: false,
    processData: false,
    dataType: "JSON",
    success: function(data)
    {

        if(data.status) //if success close modal and reload ajax table
        {
            $('#modal_form').modal('hide');
            reload_table();
        }
        else
        {
            for (var i = 0; i < data.inputerror.length; i++) 
            {
                $('[name="'+data.inputerror[i]+'"]').parent().parent().addClass('has-error'); //select parent twice to select div form-group class and add has-error class
                $('[name="'+data.inputerror[i]+'"]').next().text(data.error_string[i]); //select span help-block class set text error string
            }
        }

        $('#btnSave').text('save'); //change button text
        $('#btnSave').attr('disabled',false); //set button enable 


    },
    error: function (jqXHR, textStatus, errorThrown)
    {
        alert('Error adding / update data');
        $('#btnSave').text('save'); //change button text
        $('#btnSave').attr('disabled',false); //set button enable 

    }
});

我按下保存按钮。但是无法更新数据，没有任何反应。我需要帮助。谢谢。