Too Many Categories - Sub Category Drop Down

What version of 68 Classifieds are you running?
Example: V4.2.1 Developer

What template are you using?
3 col


Please describe in detail the issue you are having:
Im trying to split my category list down into a categories drop down list and a sub cateories drop down list (I only have two levels of categories). I have too many categories so if you are searching or placing an ad the drop down list is huge and runs off the screen.

I started in the search.tpl file by modifying the categories drop down an adding another drop down box after it.

My problem is that I have no idea how to get the second drop down box to dynamically update depending on what selection is made in the first box.

Here is my code

Code:

<p id="category">
			<label for="type">{$smarty.const.LANG_SEARCH_INCAT}{$smarty.const.LANG_COLON}</label>
			<select name="type" id="type">
						   <option value=''>{$smarty.const.LANG_SEARCH_ALLCAT}</option>
						{foreach from=$getcats item=cat}
							{if $cat.parent_id == 0}
								<option value="{$cat.id}"{if $type==$cat.id} SELECTED{/if}>{$cat.name}</option>
							{/if}
						{/foreach}
			</select>
		</p>
		<p id="subcategory">
			<label for="subtype">Sub Category{$smarty.const.LANG_COLON}</label>
			<select name="subtype" id="subtype">
						   <option value=''>{$smarty.const.LANG_SEARCH_ALLCAT}</option>		
						{foreach from=$getcats item=cat}
							{if $cat.parent_id == type}
								<option value="{$cat.id}"{if $type==$cat.id} SELECTED{/if}>{$cat.name}</option>
							{/if}
						{/foreach}
			</select>
		</p>

Do I use like onSelect Java statements? I know the extra fields do this automatically but it's using like Ajax I think. Thanks! can anyone give me the code i would use to dynamically update the second drop down?
P.S have a look iheartwheels.com at my search page to see what I mean and how far ive got (which isnt very far).
Many thanks

Yes they could be the same for each category.


Having too many categories caused an issue with these drop downs so I changed to using extra fields for all car makes and models while just keeping the very top level categories (however this stops you from being able to use the browse function to browse thorugh makes and models of cars) so im trying to switch back to using categories but without having a HUGE drop down list when you select a category for searching or posting an ad.

How would I get javascript to update the second drop down when I select the top level category from the first drop down?

Many thanks

But then wouldnt I be missing most of the categories available in the list?

Ok I think I just need to find the right balance maybe have the makes as categories and the models as extra fields.
I'll see if anyone is up for a bit of saturday work lol.
Thanks for the advice.