I want to show k2 category list in back-end and front-end item editting like this:

select main category : category1 - category2 and... and if user select category1 then appear another dropdown that shows subcategories of category1

I found the files :

I believe this is the code that is producing the category drop down: .../components/com_k2/views/item/tmpl/form.php

<tr>
<td align="right" class="key"><?php echo JText::_('Category'); ?></td>
<td><?php echo $this->lists; ?></td>
</tr>

For the frontend the file is itemform.php and can be overriden in your template folder.

For the backend is a little more complicated than that. The file is administrator/components/views/item/view.html.php and the code for the category select list is around line 385

Modifying core files is not recommended, however.

thanks for your reply , thanks GOD!!!! :)
in itemform.php , I found this :
<?php echo $this->lists; ?>
how can I edit this as I said in last post?

I'm afraid that I don't know the answer to that because I'm not a programmer.

You can however seek other developers in this forum that are willing to help you with this as a custom work.

I don't have any problem with custom work! so if anyone can do this , I pay him or her! but there is a small problem that is : I'm living in Iran and how can I pay?!!!

Hi,
I did this , but my problem now is when I select category always load on of the extrafields group , how can I solve it?