You can create your own custom elements by simply extending the
Zend_Form_Element class. Common reasons to do so
include:
Elements that share common validators and/or filters
Elements that have custom decorator functionality
There are two methods typically used to extend an element:
init(), which can be used to add custom initialization
logic to your element, and loadDefaultDecorators(),
which can be used to set a list of default decorators used by your
element.
As an example, let's say that all text elements in a form you are
creating need to be filtered with StringTrim,
validated with a common regular expression, and that you want to
use a custom decorator you've created for displaying them,
'My_Decorator_TextItem'. In addition, you have a number of standard
attributes, including 'size', 'maxLength', and 'class' you wish to
specify. You could define an element to accomplish this as follows:
<?php
class My_Element_Text extends Zend_Form_Element
{
public function init()
{
$this->addPrefixPath('My_Decorator', 'My/Decorator/', 'decorator')
->addFilters('StringTrim')
->addValidator('Regex', false, array('/^[a-z0-9]{6,}$/i'))
->addDecorator('TextItem')
->setAttrib('size', 30)
->setAttrib('maxLength', 45)
->setAttrib('class', 'text');
}
}
You could then inform your form object about the prefix path for such elements, and start creating elements:
<?php
$form->addPrefixPath('My_Element', 'My/Element/', 'element')
->addElement('text', 'foo');
The 'foo' element will now be of type My_Element_Text,
and exhibit the behaviour you've outlined.
Another method you may want to override when extending
Zend_Form_Element is the
loadDefaultDecorators() method. This method
conditionally loads a set of default decorators for your element;
you may wish to substitute your own decorators in your extending
class:
<?php
class My_Element_Text extends Zend_Form_Element
{
public function loadDefaultDecorators()
{
$this->addDecorator('ViewHelper')
->addDecorator('DisplayError')
->addDecorator('Label')
->addDecorator('HtmlTag',
array('tag' => 'div', 'class' => 'element'));
}
}
There are many ways to customize elements. Read the API
documentation of Zend_Form_Element to learn about all of the
available methods.