In Tutorial 2, an ArticleHolder has ArticlePage children.

Perhaps, sometimes, ArticlePages can be written on the same day. And maybe you only want the day it is written on to be displayed once, like a blog. Blogs can have the day of posting as a header followed by all the blog posts posted on that day.

How and where can ArticleHolder access the data of the Children to determine whether or not it should print the day.

So if $day is the same as $blog.prev.day, don't print, else print.

Is this done in the Controller or is this done in the template? What sort of code can be used to test the data held by the Children?

Or is it not possible to query Children?

There is clearly some communication going when you have $TotalItems and $Pos.

http://doc.silverstripe.com/doku.php?id=built-in-page-controls

maybe this will help you?

My dodgy code to get my original question to work.

NB. This is probably wrong on many levels, but it's a start! And if you can improve it, go ahead And it probably breaks with pagination.

class ArticleHolder extends Page {
...
function Articles(){
$data = $this->Children();
$data->sort('Date');
return $data;
}

function getDates(){
static $dates;

if (!isset($dates)) {

$data = $this->Children();
$data->sort('Date');

$dates = array();

for ($i = 0; $i < $data->TotalItems(); $i++){
$date = $data->Current()->getField('Date');
$dates[$i] = strtotime($date);
$data->next();
} // end for loop
} // end !isset($dates)

return $dates;

} // end function getDates()

function printDate(){
static $a = 0;
$dateArray = $this->getDates();

$print = true;

if ($a > 0) {
if ($dateArray[$a] == $dateArray[$a-1])
$print = false;
}

$a++;
return $print;
}

function endDate(){
static $a = 0;
$dateArray = $this->getDates();

$print = true;

if ($a < count($dateArray)) {
if ($dateArray[$a] == $dateArray[$a+1])
$print = false;
}

$a++;
return $print;
}
}

ArticleHolder.ss
<div id="Content" class="typography">      
$Content
<% control Articles %>

<% if Parent.printDate %><div class="date"><h2 class="newsDateTitle">$Date.Nice</h2><% end_if %>
<div class="newsArticle">
<h3 class="newsDateTitle"><a href="$Link" title="Read more on &quot;{$Title}&quot;">$Title</a></h3>
<p class="newsSummary">$Content.FirstParagraph <a href="$Link" title="Read more on &quot;{$Title}&quot;">Read more &gt;&gt;</a></p>

<% if Parent.endDate %></div><!-- end of div.newsArticle --><% end_if %>
</div>
<% end_control %>
</ul>
</div>