Drag and Drop...trying to make it happen

[eluser]Dyllon[/eluser]
You can try something like this, it's a quick, dirty and untested version of something I'm currently using.

Assumes your table contains the columns 'id' and 'position'

names model:

Code:

function moveName($id, $destination_id)
{

    //Do some error checking
    if ($id == $destination_id)
    {
        return FALSE;
    }

    //get destination row
    $query = $this->db->getwhere('names', array('id'=> $destination_id));
    if ($query->num_rows() == 0)
    {
        return FALSE;
    }
    else
    {
        $destination = $query->row();
    }

    //get departure row
    $query = $this->db->getwhere('names', array('id'=>$id));

    if ($query->num_rows() == 0)
    {
        return FALSE;
    }
    else
    {
        $departure = $query->row();
    }

    if ($departure->position > $destination->position)
    {
        $direction = 'up';
        $new_position = $destination->position +1;
    }
    elseif ($departure->position < $destination->position)
    {
        $direction = 'down';
        $new_position = $destination->position;
    }

    //Shift all affected names up or down
    if ( ! $this->_shiftNames( $direction, $destination->position, $departure->position ) )
    {
        return FALSE;
    }

    //Move name from departure to destination
    $this->db->where('id', $id);

    return $this->db->update('names', array('position' => $new_position));
}


function _shiftNames($direction, $start, $stop)
{
    switch ($direction)
    {
        case 'up':
        $this->db->set('position', 'position +1', FALSE);
        $this->db->where('position >', $start);
        $this->db->where('position <', $stop);
        break;

        case 'down':
        $this->db->set('position', 'position -1', FALSE);
        $this->db->where('position <=', $start);
        $this->db->where('position >', $stop);
        break;

        default:
        return FALSE;
    }

    return $this->db->update('names');
}

In your controller:

Code:

//Move a name to a new location
function ajaxMove($id = null, $destination = null)
{
    $json = array();
    if (isset($id) && isset($destination))
    {
        $json['success'] = $this->names_model->moveName($id, $destination);
    }
    else
    {
        $json['success'] = FALSE;
    }

    $this->output->set_output( json_encode($json) );
}