Failed to Update data inside Input field

I'm trying to update my data inside INPUT FIELD using a UPDATE Button. In the image below, I'll type new data in the field and press Edit button and my DB will be updated.



But I'm stuck in where clause.

$this->output->enable_profiler(TRUE); was showing that in query WHERE 'id'=NULL.  My query can't specify the id field.

*Called the model inside construct already.
view :

PHP Code:

<?php if(isset($records)) : foreach($records  as $row): ?>
<?php  echo form_open('main/update') ?>
 
<td> <input type="text" name="edit_tname" value="<?php echo $row->tname ;?>"/> </td>
<td> <input type="text" name="edit_time" value="<?php echo $row->time; ?>" /></td>

<td> <input type="submit" value="Edit"> </td>

<?php echo form_close();?>

<?php endforeach; ?>

controller :

PHP Code:

public function update_task()
        {
           $this->model_users->updateM();
           redirect('main');
        } 


model:

PHP Code:

public function updateM()
            {
                $updated_data = array(
                    'tname'=> $this->input->post('edit_tname'),
                    'time'=> $this->input->post('edit_time')
                    );
                    
                $this->db->where('id', $this->uri->segment(3));
                $this->db->update('tasks', $updated_data);
            } 


put the id in hidden input, or as part of form_open url

As Gadelat said: add a hidden field.
Like this:

Code:

<?php echo form_hidden('id', $row->id);?>

In your controller, read the value:

Code:

$id = $this->input->post('id');

Yap it worked, Thanks