I am wondering if there is a way I can auto-sort my Data Objects based on category on the font-facing part of my site. So using my dropdown for category when the user ads an object, I'd like it to be put into the appropriate "bucket" on the Resources page template.

What would be the best way to achieve this?

Do you mean sort by category? Or filter by category? There's a difference. Either one is quite easy, though.

I want to have them sorted I believe, so that my template looks like this

CATEGORY 1
Resource 1 Title
Resource 2 Title
Resource 3 Title

CATEGORY 2
Resource 1 Title
Resource 2 Title
Resource 3 Title

CATEGORY 3
Resource 1 Title
Resource 2 Title
Resource 3 Title

something like this oughta work:

public function Categories()
{
$cats = new DataObjectSet();
foreach(singleton($this->class)->dbObject('Category')->enumValues() as $category) {
$cats->push(new ArrayData(array(
'Title' => $category, 
'Resources' => $this->Resources("Category = '$category'")
)));
}
return $cats;
}

<% control Categories %>
<h3>$Title</h3>
<% control Resources %>
...
<% end_control %>
<% end_control %>

I was looking at something like that as well before I posted. I put that function into the ResourcePage Controller, but then when I add the code to my template

<% control Categories %>
<h3>$Title</h3>
<% control Resources %>
<a href="$Attachment.Link">$Attachment.Name &gt; $Description</a>
<% end_control %>
<% end_control %>

The template doesn't render. I just get a white page.

That's a PHP error. Crank up your error reporting and find out what's going on.

UncleCheese, the error is on this line:

foreach(singleton($this->class)->dbObject('Category')->enumValues() as $category) {

Any ideas?

I got it working. I replaced "$this->class" to Resources and it worked fine.

One more question - I inserted a filter on the DOM in the admin section, so I can allow the admins to filter the categories if they wanted. However, it seems when I filter by category and then re-order, it doesn't apply (I can only reorder using no filter). I want the user to be able to filter by category on the backend and sort the resources, and for that order to be applied on the templates.

Any easy way to go about this?