Zend\Form is intended primarily as a bridge between your domain models and the View Layer. It composes a thin layer of objects representing form elements, an InputFilter, and a small number of methods for binding data to and from the form and attached objects.
The Zend\Form component consists of the following objects:
- Elements, which simply consist of a name and attributes.
- Fieldsets, which extend from Elements, but allow composing other fieldsets and elements.
- Forms, which extend from Fieldsets (and thus Elements). They provide data and object binding, and compose InputFilters. Data binding is done via Zend\Stdlib\Hydrator.
To facilitate usage with the view layer, the Zend\Form component also aggregates a number of form-specific view helpers. These accept elements, fieldsets, and/or forms, and use the attributes they compose to render markup.
A small number of specialized elements are provided for accomplishing application-centric tasks. These include the Csrf element, used to prevent Cross Site Request Forgery attacks, and the Captcha element, used to display and validate CAPTCHAs.
A Factory is provided to facilitate creation of elements, fieldsets, forms, and the related input filter. The default Form implementation is backed by a factory to facilitate extension and ease the process of form creation.
The code related to forms can often spread between a variety of concerns: a form definition, an input filter definition, a domain model class, and one or more hydrator implementations. As such, finding the various bits of code and how they relate can become tedious. To simplify the situation, you can also annotate your domain model class, detailing the various input filter definitions, attributes, and hydrators that should all be used together. Zend\Form\Annotation\AnnotationBuilder can then be used to build the various objects you need.