Collection

Collections contain a repeatable set of elements.

In case of a form representing an invoice there is a collection of invoice lines which may contain fields like: product name, quantity, price per item.

Add a collection to form

// construct your fielset in one command
$form->addElement('lines', array(
    Specs::TYPE => 'collection'
    Specs::CHILDREN => array(
        'product' => array (
            Specs::TYPE => 'text'
        ),
        'quantity' => array (
            Specs::TYPE => 'text'
        ),
        'price' => array (
            Specs::TYPE => 'text'
        )
    )
));

Add an element to collection

// or add the children later
$collection = $form->getElement('lines');

$collection->addElement('total', array(
    Specs::TYPE => 'text'
));

Change an element from a collection

// alter the collection's children any time
$total = $collection->getElement('total');
$total->setAttribute('readonly', 'readonly');

Collections vs fieldsets

Similarly to fielsets, the child elements of a collection are namespaced. But they also have an index. In the example above the quantity inputs will have the name attribute set as lines[{lines_index}][quantity]

Important! Just like in the case of Fieldsets, this will have implications on the data validation and filtration.