I'm trying to output a lexicon/glossary, and have some problems grouping the output according to first letters.

The lexicon items are DataObjects attached to all pages. In the Page_Controller they are collected

	function LexiconAllAggregator() {
		$LexiconSet = DataObject::get( 
				   "Lexicon", 
				   "`PageID` IN (" . implode(",", $all_lexicon) . ")", 
				   "Term ASC", 
				   "",
				   ""
				);

		return $LexiconSet ;
	}

and output in the template

	<% control LexiconAllAggregator %>
		<h3><a href="{$Top.Link}lexikon/$ID">$Term</a></h3>
		<p>$Explanation.FirstParagraph</p>
	<% end_control %>

Now i want to group them, ie to have divs (with all first letters) after first letter of the terms change. So a new property $Break for $LexiconSet is needed which is should be calculated in the Page_Controller and checked in the template:

	<% control LexiconAllAggregator %>
		<% if Break %> <div> A B C ... </div> <% end_if %>

		<h3><a href="{$Top.Link}lexikon/$ID">$Term</a></h3>
		<p>$Explanation.FirstParagraph</p>
	<% end_control %>

But I just don't get it how it has to be done to get a new property into the DataObjectSet
I think it will start with something like that

		$LexiconSetNew = new DataObjectSet();
		foreach ( $LexiconSet as $LexiconSetSingle ) {
                           
                            //??????

		}

Thanks in advance.

Welcome to the forums! What you want to do is something like

   foreach ( $LexiconSet as $LexiconSetSingle ) {
  $LexiconSetSingle->FieldName = "Hi";
}

Or $LexiconSetSingle->setField('FieldName', 'Hi'); if you want. I believe that should work fine - the set should update with the new fields on the object, if they don't you'll have to define a new $output = new DataObjectSet() and after setting that field push the new object onto the output set and return output rather then $LexiconSet.

This isn't working in ss3?

$images= Image::get()->leftJoin("GalleryImage", "GI.ImageID = File.ID","GI")->where("GI.GalleriesID='".$this->ID."'");
foreach($images as $image) {
$image->setField('TopPos',333);
}
return $images;

I can not use TopPos in Template.

That works...!
Maybe someone can explain why I need to push the DataList into ArrayList

$images= DataList::create('Image')->leftJoin("GalleryImage", "GI.ImageID = File.ID","GI")->where("GI.GalleriesID='".$this->ID."'");
$imagesAL=new ArrayList();
$positions=$this->positionErmitteln();
foreach($images as $image) {
$image->TopPos=$positions[$image->ID]['topPos'];
$image->LeftPos=$positions[$image->ID]['leftPos'];
$imagesAL->push($image);
}
return $imagesAL;

Bump. Has anyone found any solution to this problem in SS3 that Lukin had?

Hi,
I solved my Problem in the post Above.
You can add fields temporarily like that:

iterate through the result-arraylist, add fields with the arrow-Operator,
Push the dataobject into an arraylist And Return it to the Template

Sorry, I meant how to achieve that with DataLists. After I have pushed the objects to an ArrayList, I need to create a PaginatedList from it - with which I had issues yesterday (but that's another topic).

I take it that DataLists should not be altered because they present the results of their SQL query?

And now when I try again with ArrayList, I can't even get that working like it did yesterday. However, the PaginatedList now works with ArrayList. It's just that my custom properties are not binding to the objects :/. So which ever I fix, the other will break :D. But no need for you to ask details, I try to work this out on my own and if can't get it working, I'll make another post with a clear example code - either in this topic or a new one, depending on if it's related or not. Thanks :)

skim read, may not be fully understanding. But basically sounds like this exact thing: https://docs.silverstripe.org/en/3.1/developer_guides/model/how_tos/grouping_dataobject_sets/