Question

I have a base User form that I am subclassing for each use case, i.e. Register, Edit, etc.

Some form elements are common to all use cases and for these I am using the form as an element factory, e.g. $this->addElement(‘text’, ‘first_name’, array(…)). That works fine.

For elements which are required in only some use cases, I am creating them in the base form class, but not adding them, e.g. $this->createElement(‘text’, ‘id’, array(…)). When I get to the subclass itself, that’s when I actually add these optional elements.

Now, I thought that in the subclass I would be able to simply add the element using either:

$this->addElement($this->getElement('id'));

Or

$this->addElement($this->id);

But that’s not the case. I get an exception saying I am trying to addElement(NULL).

The only way I can get the desired result is to specifically assign the create element to a member variable, then later use that variable name.

e.g. In the base form:

$this->id = $this->createElement('text', 'id', array(...));

Then in the sub class:

$this->addElement($this->id);

It seems to me that this should produce a variable name clash. If createElement is not naming my element ‘id’, what is it naming it?

EDIT

I am using the init() methods in both parent and child classes, and the child’s init() calls parent init() as its first task.

Answer 1

createElement does not add an element to the form, it just creates it. Unless you add it to your form, the form will not know about it. That’s why $this->id and
$this->getElement('id') don’t work in your first example.

In your second example, you first add the newly created element to the form (i.e. $this->id = $this->createElement('text', 'id', array(...));) and then it seems you are adding it again (i.e. $this->addElement($this->id);). I believe that there won’t be any name clash, as Zend_Form will just reassign it. Thus I think $this->addElement($this->id); is in fact not needed.

Hope this helps.