php - Multiselect input data should be inserted into database -

i want according plan

1. a form have 1 multiselect item
2. can cloned using jquery (.clone)
3. here must problem because same name of multiselect. (can change using jquery).
4. all cloned forms data should inserted database accordingly new rows.

view

echo $this->form->input('book.category.', array(                                                             'class'=>'js_cetegory',                                                             'multiple' => 'multiple',                                                             'type' => 'select',                                                             'label' => 'category',                                                             'options'=>$categories,                                                             'empty'=>'select category'                                                             )                                             );  

name change code of multiselect input when clone called

var len = $("#parent").length; $(".top:first").clone().find(".js_cetegory").attr("name", "data[book][cetegory]["+len+"][]").end().appendto('#parent'); 

my $this->data making array code

[category] => array         (             [0] => array                 (                     [0] => 1                     [1] => 2                     [2] => 7                 )              [1] =>          )      [cetegory] => array         (             [1] => array                 (                     [0] => 2                     [1] => 7                     [2] => 8                 )          ) 

instead of

[category] => array         (             [0] => array                 (                     [0] => 1                     [1] => 2                     [2] => 7                 )               [1] => array                 (                     [0] => 2                     [1] => 7                     [2] => 8                 )         ) 

cake generating field name - data[book][cetegory][0], data[book][cetegory][1] ...

it should -

echo $this->form->input('book.category.0.', array( 

but when cloning names changed data[book][cetegory][1][]

the name of field sholud -

$(".top:first").clone().find(".js_cetegory").attr("name", "data[book][cetegory][][]").end().appendto('#parent');