This short article is a reminder for me, I hope it will save me hours next time.

In a PHP script, to fetch content object nodes you can use eZContentObjectTreeNode::subtree or eZFunctionHandler::execute. The second is very practical because its syntax is similar to content fetch functions in templates. But there's one difference: when writing an attribute filter condition you have to put your condition array in another array even if there's only one condition. For example, in templates you can write :

{def $tree=fetch(content, tree, hash(parent_node_id, 2,
                     attribute_filter, array( 'name', 'like', '*ez publish*' )) )}

So, in a PHP script, I was thinking that I could write :

$tree = eZFunctionHandler::execute('content','tree', array('parent_node_id' => 2,
                     'attribute_filter' => array( 'name', 'like', '*ez publish*' )) );

But it does not work, you have to use this instead :

$tree = eZFunctionHandler::execute('content','tree', array('parent_node_id' => 2,
                     'attribute_filter' => array( array( 'name', 'like', '*ez publish*' )) ));

In fact, in the documentation of the template fetch list function about attribute filtering (parameters for fetch list and fetch tree are mostly the same), you can read:

The "attribute_filter" parameter must be an array. The first element may be set to either "and" or "or" - this controls how the matching specified in the upcoming elements should be carried out. If this parameter is omitted, the system will default to "and". The rest of the elements are arrays, each array specifies a match.

So, the first and the second examples are not correct even if the first works in templates ! Damn, this took me almost 2 hours…