php - array to string conversion error in codeigniter 3.0.1 -

i have following error message while updating records in database

severity: notice

message: array string conversion

filename: database/db_query_builder.php

line number: 662

backtrace:

file: c:\xampp\htdocs\site\application\models\class_model.php line: 48 function: where

file: c:\xampp\htdocs\site\application\controllers\class_con.php line: 107 function: update

file: c:\xampp\htdocs\site\index.php line: 292 function: require_once

here controller

function edit($id) {     $rules = [         [             'field' => 'classname',             'label' => 'class name',             'rules' => 'trim|required'         ],         [             'field' => 'inchargename',             'label' => 'incharge name',             'rules' => 'trim|required'         ],         [             'field' => 'classstrength',             'label' => 'class strength',             'rules' => 'trim|required'         ]     ];     $this->form_validation->set_rules($rules);     $class = $this->class_model->find($id)->row();       if($this->form_validation->run() == false)     {         $this->load->view('admin/class/classedit',array('class'=>$class));     }     else     {          $data['classname']      = set_value('classname');         $data['inchargename']   = set_value('inchargename');         $data['classstregth']   = set_value('classstregth');          $this->class_model->update($id,$data);         $this->session->set_flashdata('message','class has been updated successfully');         redirect('class_con/index');      } } 

and here's model

public function find($id) {      $this->db->where('id',$id);     $row = $this->db->get('class');     return $row; }  function update($data, $id) {     try{         $this->db->where('id',$id);         $this->db->update('class', $data);         return true;     }     catch(execption $e){         echo $e->getmessage();     }  } 

and here view

<?php echo form_open_multipart('class_con/edit/'.$class->id); ?>                         <div class="form-group" id="register-login-group">                             <label for="classname">class name</label>                             <div class="input-group">                                 <input type="text" class="form-control" id="classname" name="classname" value="<?php echo $class->classname; ?>" placeholder="class name">                                 <div class="input-group-addon"><i class="fa fa-pencil"></i></div>                             </div>                         </div>                         <div class="form-group" id="register-login-group">                             <label for="classname">incharge name</label>                             <div class="input-group">                                 <input type="text" class="form-control" id="inchargename" name="inchargename" value="<?php echo $class->inchargename; ?>" placeholder="incharge name">                                 <div class="input-group-addon"><i class="fa fa-pencil"></i></div>                             </div>                         </div>                         <div class="form-group" id="register-login-group">                             <label for="classname">class strength</label>                             <div class="input-group">                                 <input type="text" class="form-control" id="classstrength" name="classstrength" value="<?php echo $class->classstrength; ?>" placeholder="class stregth">                                 <div class="input-group-addon"><i class="fa fa-pencil"></i></div>                             </div>                         </div>                                  <button type="submit" class="btn btn-primary">save</button>                                 <?=anchor('class_con/index','cancel',['class'=>'btn btn-warning'])?>                     <?php echo form_close(); ?> 

in controller call update method in model line :

$this->class_model->update($id,$data); 

but in model have defined function :

function update($data, $id) {     try{         $this->db->where('id',$id);         $this->db->update('class', $data);         return true;     }     catch(execption $e){         echo $e->getmessage();     }  } 

the problem order of parameter's have passed :

change :

$this->class_model->update($data,$id);